1
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Kaur M, Cooper JC, Van Humbeck JF. Site-selective benzylic C-H hydroxylation in electron-deficient azaheterocycles. Org Biomol Chem 2024; 22:4888-4894. [PMID: 38819259 DOI: 10.1039/d4ob00268g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Benzylic C-H bonds can be converted into numerous functional groups, often by mechanisms that involve hydrogen atom transfer as the key bond breaking step. The abstracting species is most often an electrophilic radical, which makes these reactions best suited to electron-rich C-H bonds to achieve appropriate polarity matching. Thus, electron deficient systems such as pyridine and pyrimidine are relatively unreactive, and therefore underrepresented in substrate scopes. In this report, we describe a new method for heterobenzylic hydroxylation-essentially an unknown reaction in the case of pyrimidines-that makes use of an iodine(III) reagent to afford very high selectivity towards electron-deficient azaheterocycles in substrates with more than one reactive position and prevents over-oxidation to carbonyl products. The identification of key reaction byproducts supports a mechanism that involves radical coupling in the bond forming step.
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Affiliation(s)
- Milanpreet Kaur
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.
| | - Julian C Cooper
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jeffrey F Van Humbeck
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.
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2
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Shan QC, Wu YW, Chen MX, Zhao X, Loh TP, Hu XH. Synergistic Copper-Aminocatalysis for Direct Tertiary α-Alkylation of Ketones with Electron-Deficient Alkanes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2402255. [PMID: 38885363 DOI: 10.1002/advs.202402255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Revised: 05/17/2024] [Indexed: 06/20/2024]
Abstract
In this study, a novel approach for the tertiary α-alkylation of ketones using alkanes with electron-deficient C─H bonds is presented, employing a synergistic catalytic system combining inexpensive copper salts with aminocatalysis. This methodology addresses the limitations of traditional alkylation methods, such as the need for strong metallic bases, regioselectivity issues, and the risk of over alkylation, by providing a high reactivity and chemoselectivity without the necessity for pre-functionalized substrates. The dual catalytic strategy enables the direct functionalization of C(sp3)─H bonds, demonstrating remarkable selectivity in the presence of conventional C(sp3)─H bonds that are adjacent to heteroatoms or π systems, which are typically susceptible to single-electron transfer processes. The findings contribute to the advancement of alkylation techniques, offering a practical and efficient route for the construction of C(sp3)─C(sp3) bonds, and paving the way for further developments in the synthesis of complex organic molecules.
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Affiliation(s)
- Qi-Chao Shan
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
| | - You-Wei Wu
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
| | - Mu-Xiang Chen
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
| | - Xuefei Zhao
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
| | - Teck-Peng Loh
- College of Advanced Interdisciplinary Science and Technology, Henan University of Technology, 100 Lianhua Street, Zhengzhou, 450001, China
- Division of Chemistry and Biological Chemistry, School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Xu-Hong Hu
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
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3
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Zhuang Z, Sheng T, Qiao JX, Yeung KS, Yu JQ. Versatile Copper-Catalyzed γ-C(sp 3)-H Lactonization of Aliphatic Acids. J Am Chem Soc 2024. [PMID: 38867480 DOI: 10.1021/jacs.4c04043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Site-selective C(sp3)-H oxidation is of great importance in organic synthesis and drug discovery. γ-C(sp3)-H lactonization of free carboxylic acids provides the most straightforward means to prepare biologically important lactone scaffolds from abundant and inexpensive carboxylic acids; however, a versatile catalyst for this transformation with a broad substrate scope remains elusive. Herein, we report a simple yet broadly applicable and scalable γ-lactonization reaction of free aliphatic acids enabled by a copper catalyst in combination with inexpensive Selectfluor as the oxidant. This lactonization reaction exhibits compatibility with tertiary, benzylic, allylic, methylene, and primary γ-C-H bonds, affording access to a wide range of structurally diverse lactones such as spiro, fused, and bridged lactones. Notably, exclusive γ-methylene C-H lactonization of cycloalkane carboxylic acids and cycloalkane acetic acids was observed, giving either fused or bridged γ-lactones that are difficult to access by other methods. δ-C-H lactonization was only favored in the presence of tertiary δ-C-H bonds. The synthetic utility of this methodology was demonstrated by the late-stage functionalization of amino acids, drug molecules, and natural products, as well as a two-step total synthesis of (iso)mintlactones (the shortest synthesis reported to date).
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Affiliation(s)
- Zhe Zhuang
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Tao Sheng
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jennifer X Qiao
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, P.O. Box 4000, Princeton, New Jersey 08543, United States
| | - Kap-Sun Yeung
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Jin-Quan Yu
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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4
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Gao X, He H, Miao K, Zhang L, Ni SF, Li M, Guo W. Electrochemical Allylic C(sp 3)-H Isothiocyanation via [3,3]-Sigmatropic Rearrangement. Org Lett 2024; 26:4554-4559. [PMID: 38767297 DOI: 10.1021/acs.orglett.4c01463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The direct allylic C(sp3)-H functionalization provides a straightforward protocol for the synthesis of valuable molecules. We report herein the first chemo- and site-selective method for allylic C(sp3)-H isothiocyanation of various internal alkenes under mild electrochemical conditions. This method exhibits broad functional group tolerance and excellent selectivity and can be applied for late-stage isothiocyanation of bioactive molecules. Combined experimental and computational studies indicate that the reaction proceeds via an unexpected [3,3]-sigmatropic rearrangement.
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Affiliation(s)
- Xuezhuang Gao
- College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, 266042 Qingdao, P. R. China
| | - Hui He
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong, Shantou University, Shantou, 515063 Guangdong, P. R. China
| | - Kaili Miao
- College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, 266042 Qingdao, P. R. China
| | - Linbao Zhang
- College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, 266042 Qingdao, P. R. China
| | - Shao-Fei Ni
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong, Shantou University, Shantou, 515063 Guangdong, P. R. China
| | - Ming Li
- College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, 266042 Qingdao, P. R. China
| | - Weisi Guo
- College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, 266042 Qingdao, P. R. China
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5
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Sun K, Sun T, Jiang Y, Shi J, Sun W, Zheng Y, Wang Z, Li Z, Lv X, Zhang X, Luo F, Liu S. Iron-catalyzed benzylic C-H thiolation via photoinduced ligand-to-metal charge-transfer. Chem Commun (Camb) 2024; 60:5755-5758. [PMID: 38747147 DOI: 10.1039/d4cc01574f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Here, we describe an iron-catalyzed benzylic C-H thiolation of alkylarenes via photoinduced ligand-to-metal charge-transfer. The protocol features operational simplicity, mild reaction conditions, and the use of FeCl3 as catalyst and thiols/disulfides as sulfur sources, which enables the transformation of diverse benzylic C-H bonds into C-S bonds with a high efficiency.
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Affiliation(s)
- Kaiting Sun
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Tianyi Sun
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Yuxin Jiang
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Jiayue Shi
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Wenlu Sun
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Youyou Zheng
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Zhixuan Wang
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Ziyu Li
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Xiaoqing Lv
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Xingxian Zhang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.
| | - Fan Luo
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
| | - Shihui Liu
- College of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, P. R. China.
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6
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Sreedharan R, Gandhi T. Masters of Mediation: MN(SiMe 3) 2 in Functionalization of C(sp 3)-H Latent Nucleophiles. Chemistry 2024; 30:e202400435. [PMID: 38497321 DOI: 10.1002/chem.202400435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/16/2024] [Accepted: 03/18/2024] [Indexed: 03/19/2024]
Abstract
Organoalkali compounds have undergone a far-reaching transformation being a coupling partner to a mediator in unusual organic conversions which finds its spot in the field of sustainable synthesis. Transition-metal catalysis has always been the priority in C(sp3)-H bond functionalization, however alternatively, in recent times this has been seriously challenged by earth-abundant alkali metals and their complexes arriving at new sustainable organometallic reagents. In this line, the importance of MN(SiMe3)2 (M=Li, Na, K & Cs) reagent revived in C(sp3)-H bond functionalization over recent years in organic synthesis is showcased in this minireview. MN(SiMe3)2 reagent with higher reactivity, enhanced stability, and bespoke cation-π interaction have shown eye-opening mediated processes such as C(sp3)-C(sp3) cross-coupling, radical-radical cross-coupling, aminobenzylation, annulation, aroylation, and other transformations to utilize readily available petrochemical feedstocks. This article also emphasizes the unusual reactivity of MN(SiMe3)2 reagent in unreactive and robust C-X (X=O, N, F, C) bond cleavage reactions that occurred alongside the C(sp3)-H bond functionalization. Overall, this review encourages the community to exploit the untapped potential of MN(SiMe3)2 reagent and also inspires them to take up this subject to even greater heights.
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Affiliation(s)
- Ramdas Sreedharan
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
| | - Thirumanavelan Gandhi
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
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7
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Zhou YQ, He KC, Zheng WH, Lv JF, He SM, Yu N, Yang YB, Liu LY, Jiang K, Wei Y. 1,5-Hydrogen atom transfer of α-iminyl radical cations: a new platform for relay annulation for pyridine derivatives and axially chiral heterobiaryls. Chem Sci 2024; 15:7502-7514. [PMID: 38784726 PMCID: PMC11110145 DOI: 10.1039/d4sc01858c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
The exploitation of new reactive species and novel transformation modes for their synthetic applications have significantly promoted the development of synthetic organic methodology, drug discovery, and advanced functional materials. α-Iminyl radical cations, a class of distonic ions, exhibit great synthetic potential for the synthesis of valuable molecules. For their generation, radical conjugate addition to α,β-unsaturated iminium ions represents a concise yet highly challenging route, because the in situ generated species are short-lived and highly reactive and they have a high tendency to cause radical elimination (β-scission) to regenerate the more stable iminium ions. Herein, we report a new transformation mode of the α-iminyl radical cation, that is to say, 1,5-hydrogen atom transfer (1,5-HAT). Such a strategy can generate a species bearing multiple reactive sites, which serves as a platform to realize (asymmetric) relay annulations. The present iron/secondary amine synergistic catalysis causes a modular assembly of a broad spectrum of new structurally fused pyridines including axially chiral heterobiaryls, and exhibits good functional group tolerance. A series of mechanistic experiments support the α-iminyl radical cation-induced 1,5-HAT, and the formation of several radical species in the relay annulations. Various synthetic transformations of the reaction products demonstrate the usefulness of this relay annulation protocol for the synthesis of significant molecules.
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Affiliation(s)
- Yu-Qiang Zhou
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Kui-Cheng He
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Wei-Hao Zheng
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Jing-Fang Lv
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Shi-Mei He
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Ning Yu
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Yun-Bo Yang
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Lv-Yan Liu
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Kun Jiang
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
| | - Ye Wei
- Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University Chongqing 400715 China
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8
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Liu D, Zhang Y, Niu D. Preparing glycosyl benzothiazoles from 2-isocyanoaryl thioethers and glycosyl radicals under thermal conditions. Chem Commun (Camb) 2024; 60:5498-5501. [PMID: 38696183 DOI: 10.1039/d4cc00648h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Herein, we report a method for preparing glycosyl benzothiazoles via radical cascade cyclization, in which glycosyl radicals are generated from readily available and bench-stable allyl glycosyl sulfones. This cascade reaction proceeds under simple conditions and tolerates a broad substrate scope in high yield with excellent stereoselectivity. Mechanistic studies support that the reactions proceed via the intermediacy of imidoyl radicals, which attack the appended sulfide unit by a SH2 process to forge the thiazole ring.
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Affiliation(s)
- Daqi Liu
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu 610041, China.
| | - Yang Zhang
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu 610041, China.
| | - Dawen Niu
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu 610041, China.
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9
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Xue M, Pan T, Shao Z, Wang W, Li H, Zhao L, Zhou X, Zhang Y. Sustainable Electrochemical Benzylic C-H Oxidation Using MeOH as an Oxygen Source. CHEMSUSCHEM 2024; 17:e202400028. [PMID: 38225209 DOI: 10.1002/cssc.202400028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 01/15/2024] [Indexed: 01/17/2024]
Abstract
New methods and strategies for the direct oxidation of benzylic C-H bonds are highly desirable, owing to the importance of ketone motifs in significant organic transformations and the synthesis of valuable molecules, including pharmaceuticals, pesticides, and fine chemicals. Herein, we describe an electrochemical benzylic C-H oxidation strategy for the synthesis of ketones using MeOH as an oxygen source. Inexpensive and safe KBr serves as both an electrolyte and a bromide radical precursor in the reaction. This transformation also offers several advantages such as mild conditions, broad functional group tolerance, and operational simplicity. Mechanistic investigations by control experiments, radical scavenging experiments, electron paramagnetic resonance (EPR), kinetic studies, cyclic voltammetry (CV), and in-situ Fourier transform infrared (FTIR) spectroscopy support a pathway involving the formation and transformation of benzyl methyl ether via hydrogen atom transfer (HAT) and single-electron transfer (SET). The practical application of our strategy is highlighted by the successful synthesis of five pharmaceuticals, namely lenperone, melperone, diphenhydramine, cinnarizine, and flunarizine.
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Affiliation(s)
- Meng Xue
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
| | - Tao Pan
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
| | - Zhichao Shao
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
| | - Wenxuan Wang
- School of Ecology and Environment, Ningxia University, 489 Helan Mountain West Road, Yinchuan, 750021, China
| | - Hu Li
- School of Ecology and Environment, Ningxia University, 489 Helan Mountain West Road, Yinchuan, 750021, China
| | - Lixing Zhao
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
| | - Xin Zhou
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
| | - Yuexia Zhang
- College of Chemistry and Chemical Engineering, Qingdao University, 308 Ningxia Road, Qingdao, 266071, China
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10
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Qian P, Zhu D, Wang X, Sun Q, Zhang S. Electrochemical Benzylic C(sp 3)-H Imidation Enabled by Benzoic Acid Derived Radicals. J Org Chem 2024; 89:6395-6404. [PMID: 38621116 DOI: 10.1021/acs.joc.4c00425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
We developed an electrochemical approach for benzylic C(sp3)-H imidation by virtue of the in situ generated oxygen-centered radicals (OCRs). The electrochemical imidation provides a complementary approach to giving distinct imide products compared with previous acyloxylation products. This protocol exhibits good site selectivity and broad substrate generality. Moreover, the utility of the OCR-mediated protocol was extended to the electrochemical oxidation of silane, and its robustness was also highlighted by the imidation of complex substrates, which would otherwise be inaccessible for previous approaches. A plausible reaction mechanism was proposed to rationalize the experimental observations.
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Affiliation(s)
- Peng Qian
- Engineering Research Center of Biomass Conversion and Pollution Prevention of Anhui Educational Institutions, Biomass-Derived, Functional Oligosaccharides Engineering Technology Research Center of Anhui Province, School of Chemistry and Material Engineering, Fuyang Normal University, Fuyang, Anhui 236037, China
| | - Dan Zhu
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, China
| | - Xiaoli Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, China
| | - Qi Sun
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Sheng Zhang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, China
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11
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Liu J, Du J, Zhang LB, Li M, Guo W. Electrochemical Benzylic C-H Amination via N-Aminopyridinium. J Org Chem 2024; 89:6465-6473. [PMID: 38644574 DOI: 10.1021/acs.joc.4c00502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
An electrochemical protocol for benzylic C(sp3)-H aminopyridylation via direct C-H/N-H cross-coupling of alkylarenes with N-aminopyridinium triflate has been developed. This method features excellent site-selectivity, broad substrate scope, redox reagent-free and facile scalability. The generated benzylaminopyridiniums can be readily converted to benzylamines via electroreductive N-N bond cleavage.
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Affiliation(s)
- Jingwei Liu
- College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Jinyao Du
- College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Lin-Bao Zhang
- College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Ming Li
- College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Weisi Guo
- College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
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12
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Lal N, Shirsath SB, Singh P, Deepshikha, Shaikh AC. Allylsilane as a versatile handle in photoredox catalysis. Chem Commun (Camb) 2024; 60:4633-4647. [PMID: 38606528 DOI: 10.1039/d4cc00734d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
Organosilanes have secured a special place in the synthetic world for several decades. However, among them, allylsilanes are a choice reagent for organic chemists to develop novel organic transformations. In recent years researchers have proved that visible-light photoredox catalysis has emerged as one of the most mild, sustainable, straightforward, and efficient strategies to construct simple to complex molecules with or without enantioselectivity. This review provides an in-depth analysis of recent advances and strategies employed in visible-light photoredox catalysis for allylsilane and its analogues for the development of various organic transformations. The review is divided into sections, each focused on a specific reactivity of allylsilane under light irradiation with C(sp2) center arene or alkene, C(sp2) center carbonyl, and C(sp3) center carbon functionality. In this review, we present optimization data, reaction scope, and mechanistic aspects to bring forward specific reactivity and selectivity trends of allylsilane in photoredox conditions.
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Affiliation(s)
- Nand Lal
- Department of Chemistry, Indian Institute of Technology, Ropar (IIT Ropar), Rupnagar, Punjab 140 001, India.
| | - Sanket B Shirsath
- Department of Chemistry, Indian Institute of Technology, Ropar (IIT Ropar), Rupnagar, Punjab 140 001, India.
| | - Puja Singh
- Department of Chemistry, Indian Institute of Technology, Ropar (IIT Ropar), Rupnagar, Punjab 140 001, India.
| | - Deepshikha
- Department of Chemistry, Indian Institute of Technology, Ropar (IIT Ropar), Rupnagar, Punjab 140 001, India.
| | - Aslam C Shaikh
- Department of Chemistry, Indian Institute of Technology, Ropar (IIT Ropar), Rupnagar, Punjab 140 001, India.
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13
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Dai NN, Lu YJ, Wu ZQ, Zhou Y, Tong Y, Tang K, Li Q, Zhang JQ, Liu Y, Wei WT. Copper-Catalyzed Radical Relay 1,3-Carbocarbonylation across Two Distinct C═C Bonds. Org Lett 2024; 26:3014-3019. [PMID: 38547326 DOI: 10.1021/acs.orglett.4c00613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
The radical relay provides an effective paradigm for intermolecular assembly to achieve functionalization across remote chemical bonds. Herein, we report the first radical relay 1,3-carbocarbonylation of α-carbonyl alkyl bromides across two separate C═C bonds. The reaction is highly chemo- and regioselective, with two C(sp3)-C(sp3) bonds and one C═O bond formed in a single orchestrated operation. In addition, the synthesis method under mild conditions and using inexpensive copper as the catalyst allows facile access to structurally diverse 1,3-carbocarbonylation products. The plausible mechanism is investigated through a series of control experiments, including radical trapping, radical clock experiments, critical intermediate trapping, and 18O labeling experiment.
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Affiliation(s)
- Nan-Nan Dai
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Yue-Jiao Lu
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Zhong-Qi Wu
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Yu Zhou
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Ying Tong
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Keqi Tang
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Qiang Li
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252000, China
| | - Jun-Qi Zhang
- Advanced Research Institute and Department of Chemistry, Taizhou University, Jiaojiang 318000, China
| | - Yu Liu
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
| | - Wen-Ting Wei
- School of Materials Science and Chemical Engineering, Institute of Mass Spectrometry, Health Science Center, Ningbo University, Zhejiang 315211, China
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14
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Liu C, Chen F, Zhao BH, Wu Y, Zhang B. Electrochemical hydrogenation and oxidation of organic species involving water. Nat Rev Chem 2024; 8:277-293. [PMID: 38528116 DOI: 10.1038/s41570-024-00589-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2024] [Indexed: 03/27/2024]
Abstract
Fossil fuel-driven thermochemical hydrogenation and oxidation using high-pressure H2 and O2 are still popular but energy-intensive CO2-emitting processes. At present, developing renewable energy-powered electrochemical technologies, especially those using clean, safe and easy-to-handle reducing agents and oxidants for organic hydrogenation and oxidation reactions, is urgently needed. Water is an ideal carrier of hydrogen and oxygen. Electrochemistry provides a powerful route to drive water splitting under ambient conditions. Thus, electrochemical hydrogenation and oxidation transformations involving water as the hydrogen source and oxidant, respectively, have been developed to be mild and efficient tools to synthesize organic hydrogenated and oxidized products. In this Review, we highlight the advances in water-participating electrochemical hydrogenation and oxidation reactions of representative organic molecules. Typical electrode materials, performance metrics and key characterization techniques are firstly introduced. General electrocatalyst design principles and controlling the microenvironment for promoting hydrogenation and oxygenation reactions involving water are summarized. Furthermore, paired hydrogenation and oxidation reactions are briefly introduced before finally discussing the challenges and future opportunities of this research field.
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Affiliation(s)
- Cuibo Liu
- Institute of Molecular Plus, Department of Chemistry, School of Science, Tianjin University, Tianjin, China
| | - Fanpeng Chen
- Institute of Molecular Plus, Department of Chemistry, School of Science, Tianjin University, Tianjin, China
| | - Bo-Hang Zhao
- Institute of Molecular Plus, Department of Chemistry, School of Science, Tianjin University, Tianjin, China
| | - Yongmeng Wu
- Institute of Molecular Plus, Department of Chemistry, School of Science, Tianjin University, Tianjin, China
| | - Bin Zhang
- Institute of Molecular Plus, Department of Chemistry, School of Science, Tianjin University, Tianjin, China.
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology, Tianjin University, Tianjin, China.
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15
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Huang Y, Wang M, Liu W, Wu Q, Hu P. Unraveling the Prominent Existence of Trace Metals in Photocatalysis: Exploring Iron Impurity Effects. J Org Chem 2024; 89:4156-4164. [PMID: 38450620 DOI: 10.1021/acs.joc.4c00155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Metal impurities can complicate the identification of active catalyst species in transition metal catalysis and electrocatalysis, potentially leading to misleading findings. This study investigates the influence of metal impurities on photocatalysis. Specifically, the photocatalytic reaction of inert alkanes using chlorides without the use of an external photocatalyst was studied, achieving successful C(sp3)-H functionalization. The observations reveal that Fe and Cu impurities are challenging to avoid in a typical laboratory environment and are prominently present in normal reaction systems, and iron impurities play a dominant role in the aforementioned apparent 'metal-free' reaction. Additionally, iron exhibits significantly higher catalytic activity compared to Cu, Ce, and Ni at low metal concentrations in the photocatalytic C(sp3)-H functionalization using chlorides. Considering the widespread presence of Fe and Cu impurities in typical laboratory environments, this study serves as a reminder of their involvement in reaction processes.
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Affiliation(s)
- Yahao Huang
- Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, P. R. China
| | - Miao Wang
- Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, P. R. China
| | - Wei Liu
- Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, P. R. China
| | - Qiang Wu
- Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, P. R. China
| | - Peng Hu
- Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, P. R. China
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16
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Chen YB, Liu LG, Wang ZQ, Chang R, Lu X, Zhou B, Ye LW. Enantioselective functionalization of unactivated C(sp 3)-H bonds through copper-catalyzed diyne cyclization by kinetic resolution. Nat Commun 2024; 15:2232. [PMID: 38472194 PMCID: PMC10933314 DOI: 10.1038/s41467-024-46288-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/21/2024] [Indexed: 03/14/2024] Open
Abstract
Site- and stereoselective C-H functionalization is highly challenging in the synthetic chemistry community. Although the chemistry of vinyl cations has been vigorously studied in C(sp3)-H functionalization reactions, the catalytic enantioselective C(sp3)-H functionalization based on vinyl cations, especially for an unactivated C(sp3)-H bond, has scarcely explored. Here, we report an asymmetric copper-catalyzed tandem diyne cyclization/unactivated C(sp3)-H insertion reaction via a kinetic resolution, affording both chiral polycyclic pyrroles and diynes with generally excellent enantioselectivities and excellent selectivity factors (up to 750). Importantly, this reaction demonstrates a metal-catalyzed enantioselective unactivated C(sp3)-H functionalization via vinyl cation and constitutes a kinetic resolution reaction based on diyne cyclization. Theoretical calculations further support the mechanism of vinyl cation-involved C(sp3)-H insertion reaction and elucidate the origin of enantioselectivity.
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Affiliation(s)
- Yang-Bo Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Li-Gao Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Zhe-Qi Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Rong Chang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Xin Lu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Bo Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Long-Wu Ye
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China.
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17
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He C, Wang Q, Zhou X, Yi L, Zhang Z, Zhang C, Xie H, Huang Q, Qiu G, Yang M. Photocatalytic Cyclization Cascades by Radical Relay toward Pyrrolo[1,2- a]indoles: Synthesis, Mechanism, and Application. J Org Chem 2024; 89:3509-3524. [PMID: 38362658 DOI: 10.1021/acs.joc.3c02959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
A photocatalytic annulation cascade of unactivated N-alkene-linked indoles with Langlois' reagent by a radical relay is developed at room temperature under blue LED irradiation. The reaction afforded a series of tri/difluoromethylated pyrrolo[1,2-a]indoles in moderate to good yields. The DFT study suggests that the reaction is ascribed to a rhodamine 6G-induced cyclization cascade involving vinyl addition-radical relay and hydrogen-atom-abstraction (HAA) processes, and interestingly, pyrrolo[1,2-a]indoles are applied as fluorescent dyes into the fluorescence spectrum and live-cell imaging. This paper represents an initial example on photocatalytic cyclization cascades by radical relay and the HAA process.
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Affiliation(s)
- Chen He
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Qi Wang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Xiaoyang Zhou
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Lin Yi
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Zhiqiang Zhang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Chun Zhang
- School of Pharmaceutical and Materials Engineering, Taizhou University, Taizhou, Zhejiang Province 318000, China
| | - Haijiao Xie
- Hangzhou Yanqu Information Technology Co., Ltd., Y2, second Floor, Building 2, Xixi Legu Creative Pioneering Park, No. 712 Wen'er West Road, Xihu District, Hangzhou City, Zhejiang Province 310003, China
| | - Qitong Huang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Guanyinsheng Qiu
- College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001 Zhejiang, China
| | - Min Yang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
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18
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Deng Y, Hu Z, Xue J, Yin J, Zhu T, Liu S. Visible-Light-Promoted α-C(sp 3)-H Amination of Ethers with Azoles and Amides. Org Lett 2024; 26:933-938. [PMID: 38241172 DOI: 10.1021/acs.orglett.3c04291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
A visible-light-induced highly efficient C(sp3)-H amination of ethers with amides and azoles has been presented under mild conditions via a nitrogen- and carbon-centered radical coupling process. This protocol successfully utilizes 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tert-butyl nitrite (TBN) as cocatalysts to deliver the aminated products of ethers under aerobic conditions. Notably, the developed reaction features the corresponding products in good yields (up to 93%) with a wide substrate scope. The mechanistic study indicates that C-N bond formation proceeds via a direct radical cross-coupling process. Preliminary biological activity analysis indicates that the resulting products have good and selective inhibitory activity on osteosarcoma (OS) cell lines and are promising for use as hits for drug discovery.
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Affiliation(s)
- Yaqi Deng
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Zongjing Hu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Jian Xue
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Jiabin Yin
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Tong Zhu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Shunying Liu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
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19
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Mandal M, Buss JA, Chen SJ, Cramer CJ, Stahl SS. Mechanistic insights into radical formation and functionalization in copper/ N-fluorobenzenesulfonimide radical-relay reactions. Chem Sci 2024; 15:1364-1373. [PMID: 38274066 PMCID: PMC10806759 DOI: 10.1039/d3sc03597b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/09/2023] [Indexed: 01/27/2024] Open
Abstract
Copper-catalysed radical-relay reactions that employ N-fluorobenzenesulfonimide (NFSI) as the oxidant have emerged as highly effective methods for C(sp3)-H functionalization. Herein, computational studies are paired with experimental data to investigate a series of key mechanistic features of these reactions, with a focus on issues related to site-selectivity, enantioselectivity, and C-H substrate scope. (1) The full reaction energetics of enantioselective benzylic C-H cyanation are probed, and an adduct between Cu and the N-sulfonimidyl radical (˙NSI) is implicated as the species that promotes hydrogen-atom transfer (HAT) from the C-H substrate. (2) Benzylic versus 3° C-H site-selectivity is compared with different HAT reagents: Cu/˙NSI, ˙OtBu, and Cl˙, and the data provide insights into the high selectivity for benzylic C-H bonds in Cu/NFSI-catalyzed C-H functionalization reactions. (3) The energetics of three radical functionalization pathways are compared, including radical-polar crossover (RPC) to generate a carbocation intermediate, reductive elimination from a formal CuIII organometallic complex, and radical addition to a Cu-bound ligand. The preferred mechanism is shown to depend on the ligands bound to copper. (4) Finally, the energetics of three different pathways that convert benzylic C-H bonds into benzylic cations are compared, including HAT/ET (ET = electron transfer), relevant to the RPC mechanism with Cu/NFSI; hydride transfer, involved in reactions with high-potential quinones; and sequential ET/PT/ET (PT = proton transfer), involved in catalytic photoredox reactions. Collectively, the results provide mechanistic insights that establish a foundation for further advances in radical-relay C-H functionalization reactions.
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Affiliation(s)
- Mukunda Mandal
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota 207 Pleasant Street SE Minneapolis MN 55455 USA
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
| | - Joshua A Buss
- Department of Chemistry, University of Wisconsin-Madison 1101 University Avenue Madison WI 53706 USA
| | - Si-Jie Chen
- Department of Chemistry, University of Wisconsin-Madison 1101 University Avenue Madison WI 53706 USA
| | - Christopher J Cramer
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota 207 Pleasant Street SE Minneapolis MN 55455 USA
| | - Shannon S Stahl
- Department of Chemistry, University of Wisconsin-Madison 1101 University Avenue Madison WI 53706 USA
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20
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Chen SJ, Krska SW, Stahl SS. Copper-Catalyzed Benzylic C-H Cross-Coupling Enabled by Redox Buffers: Expanding Synthetic Access to Three-Dimensional Chemical Space. Acc Chem Res 2023; 56:3604-3615. [PMID: 38051914 PMCID: PMC10902864 DOI: 10.1021/acs.accounts.3c00580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
ConspectusCross-coupling methods are the most widely used synthetic methods in medicinal chemistry. Existing reactions are dominated by methods such as amide coupling and arylation reactions that form bonds to sp2-hybridized carbon atoms and contribute to the formation of "flat" molecules. Evidence that three-dimensional structures often have improved physicochemical properties for pharmaceutical applications has contributed to growing demand for cross-coupling methods with sp3-hybridized reaction partners. Substituents attached to sp3 carbon atoms are intrinsically displayed in three dimensions. These considerations have led to efforts to establish reactions with sp3 cross-coupling partners, including alkyl halides, amines, alcohols, and carboxylic acids. As C(sp3)-H bonds are much more abundant that these more conventional coupling partners, we have been pursuing C(sp3)-H cross-coupling reactions that achieve site-selectivity, synthetic utility, and scope competitive with conventional coupling reactions.In this Account, we outline Cu-catalyzed oxidative cross-coupling reactions of benzylic C(sp3)-H bonds with diverse nucleophilic partners. These reactions commonly use N-fluorobenzenesulfonimide (NFSI) as the oxidant. The scope of reactivity is greatly improved by using a "redox buffer" that ensures that the Cu catalyst is available in the proper redox state to promote the reaction. Early precedents of catalytic Cu/NFSI oxidative coupling reactions, including C-H cyanation and arylation, did not require a redox buffer, but reactions with other nucleophiles, such as alcohols and azoles, were much less effective under similar conditions. Mechanistic studies show that some nucleophiles, such as cyanide and arylboronic acids, promote in situ reduction of CuII to CuI, contributing to successful catalytic turnover. Poor reactivity was observed with nucleophiles, such as alcohols, that do not promote CuII reduction in the same manner. This insight led to the identification of sacrificial reductants, termed "redox buffers", that support controlled generation of CuI during the reactions and enable successful benzylic C(sp3)-H cross-coupling with diverse nucleophiles. Successful reactions include those that feature direct coupling of (hetero)benzylic C-H substrates with coupling partners (alcohols, azoles) and sequential C(sp3)-H functionalization/coupling reactions. The latter methods feature generation of a synthetic linchpin that can undergo subsequent reaction with a broad array of nucleophiles. For example, halogenation/substitution cascades afford benzylic amines, (thio)ethers, and heterodiarylmethane derivatives, and an isocyanation/amine-addition sequence generates diverse benzylic ureas.Collectively, these Cu-catalyzed (hetero)benzylic C(sp3)-H cross-coupling reactions rapidly access diverse molecules. Analysis of their physicochemical and topological properties highlights the "drug-likeness" and enhanced three-dimensionality of these products relative to existing bioactive molecules. This consideration, together with the high benzylic C-H site-selectivity and the broad scope of reactivity enabled by the redox buffering strategy, makes these C(sp3)-H cross-coupling methods ideally suited for implementation in high-throughput experimentation platforms to explore novel chemical space for drug discovery and related applications.
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Affiliation(s)
- Si-Jie Chen
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, Wisconsin, 53706, United States
- Department of Discovery Chemistry, Merck & Co., Inc., 213 E Grand Avenue, South San Francisco, California, 94030, United States
| | - Shane W. Krska
- Department of Discovery Chemistry, Merck & Co., Inc., 126 East Lincoln Ave., Rahway, New Jersey 07065, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, Wisconsin, 53706, United States
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21
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Cheng Z, Yang T, Li C, Deng Y, Zhang F, Chen P, Lin Z, Ma S, Liu G. Site-Selective sp 2 C-H Cyanation of Allenes via Copper-Catalyzed Radical Relay. J Am Chem Soc 2023; 145:25995-26002. [PMID: 38011726 DOI: 10.1021/jacs.3c11368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Compared with the extensively reported hydrogen atom transfer (HAT) at sp3 C-H, abstraction of hydrogen atoms at the sp2 carbon is extremely rare. Here, we communicate the site-selective cyanation of the sp2 C-H bond of allenes using the strategy of copper-catalyzed radical relay. The reactions afford various allenyl nitriles directly from simple allenes with a broad substrate scope and a remarkable functional group compatibility under mild conditions. These reactions exhibit excellent site-selectivity toward sp2 C-H, which can be attributed to the unique pocket created by the Cu-bound nitrogen-centered radical. The favorable HAT on sp2 C-H is due to crucial hydrogen bonding between the fluoride bonded to the Cu(II) center and the hydrogen atom at the allylic position. These features enable the late-stage functionalization of druglike bioactive molecules containing an allene motif.
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Affiliation(s)
- Zhongming Cheng
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Tilong Yang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Can Li
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yunshun Deng
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Fangjia Zhang
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Pinhong Chen
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Shengming Ma
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Guosheng Liu
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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22
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Li HH, Chen X, Kramer S. Recent developments for intermolecular enantioselective amination of non-acidic C(sp 3)-H bonds. Chem Sci 2023; 14:13278-13289. [PMID: 38033905 PMCID: PMC10686044 DOI: 10.1039/d3sc04643e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 11/07/2023] [Indexed: 12/02/2023] Open
Abstract
Enantioenriched chiral amines are of exceptional importance in the pharmaceutical industry. Recently, several new methods for the installation of these functional groups directly from non-acidic C(sp3)-H bonds by catalytic intermolecular enantioselective amination have been reported. These methods represent significant advances of the field and most of them display high levels of enantioselectivity, utilize the C(sp3)-H substrate as the limiting reagent, feature good functional group tolerance, and show compatibility with late-stage C(sp3)-H amination of advanced substrates. This perspective provides an overview of the recent developments in this rapidly advancing field and outlines possibilities and limitations, which will help identify unsolved challenges and guide future research efforts.
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Affiliation(s)
- Heng-Hui Li
- Department of Chemistry, Technical University of Denmark 2800 Kgs. Lyngby Denmark
| | - Xuemeng Chen
- Department of Chemistry, Technical University of Denmark 2800 Kgs. Lyngby Denmark
| | - Søren Kramer
- Department of Chemistry, Technical University of Denmark 2800 Kgs. Lyngby Denmark
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23
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III R, Lujan B, Martinez A, Manasi R, DeBow JD, Kou KGM. A Fenton Approach to Aromatic Radical Cations and Diarylmethane Synthesis. J Org Chem 2023; 88:15060-15066. [PMID: 37847050 PMCID: PMC10629232 DOI: 10.1021/acs.joc.3c01505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Indexed: 10/18/2023]
Abstract
Manipulating carbon-centered radicals to add to electron-deficient systems is a well-precedented process. By coupling the Fe(II)-mediated Fenton reaction with the Fe(III)-mediated single-electron oxidation of anisolic compounds, we demonstrate how electron-rich carbon-centered radicals can react with electron-rich arenes through a radical-polar cascade pathway. This bioinspired approach produces diarylmethane derivatives from simple unfunctionalized precursors.
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Affiliation(s)
- Robert
Crowley III
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, California 92521, United States
| | | | | | - Roni Manasi
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, California 92521, United States
| | - Justin D. DeBow
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, California 92521, United States
| | - Kevin G. M. Kou
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, California 92521, United States
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24
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Mörsdorf JM, Ballmann J. Coordination-Induced Radical Generation: Selective Hydrogen Atom Abstraction via Controlled Ti-C σ-Bond Homolysis. J Am Chem Soc 2023; 145:23452-23460. [PMID: 37861658 DOI: 10.1021/jacs.3c05748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A method for the generation of transient alkyl radicals via homolytic Ti-C bond cleavage was developed by employing a tailor-made organotitanium half-cage complex. In contrast to established metal-mediated radical initiation protocols via thermal or photochemical M-C σ-bond homolysis, radical formation is triggered solely by coordination of a solvent molecule (thf) to a titanium(IV) center. During the reaction, the nonstabilized alkyl radical is formed along with a persistent titanium(III) metalloradical, thus taming the former transient radical (persistent radical effect). Radical coupling and hydrogen atom abstraction (HAT) reactions have been explored not only experimentally but also computationally and by means of kinetic analysis. Exploiting these findings led to the development of selective HAT transformations, for example, with 9,10-dihydroanthracene. Deuterium labeling studies using selectively deuterated alkyls and 9,10-dihydroanthracene-d4 confirmed a radical pathway, which was underpinned by developing a radical-radical cross-coupling reaction for transferring the alkyl radical to a stable Sn-centered radical. To set the stage for an application in organic synthesis, a 5-endo-trig radical cyclization based on our methodology was established, and a dihydroxylated sesquiterpene was thus prepared in high diastereomeric excess.
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Affiliation(s)
- Jean-Marc Mörsdorf
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, D-69120 Heidelberg, Germany
| | - Joachim Ballmann
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, D-69120 Heidelberg, Germany
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25
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Mandal T, Das S, Maji R, De Sarkar S. Visible-Light-Induced Hydrogen Atom Transfer En Route to Exocylic Alkenylation of Cyclic Ethers Enabled by Electron Donor-Acceptor Complex. Org Lett 2023; 25:7727-7732. [PMID: 37844302 DOI: 10.1021/acs.orglett.3c03099] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
An electron donor-acceptor (EDA)-triggered hydrogen atom transfer (HAT) process is developed for the efficient generation of an α-alkoxy radical from cyclic ethers to synthesize exocyclic alkenylated ethers with exclusive E-selectivity. A judiciously chosen donor-acceptor pair (DABCO and maleimide) serves as the desired HAT reagent under visible light irradiation without using any photocatalyst or peroxide. A wide variety of substrates were explored to demonstrate the diverse applicability and practical viability of this cross-dehydrogenative transformation. Detailed mechanistic studies revealed a radical reaction pathway under the oxidative environment.
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Affiliation(s)
- Tanumoy Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, West Bengal, India
| | - Sanju Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, West Bengal, India
| | - Rohan Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, West Bengal, India
| | - Suman De Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, West Bengal, India
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26
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Zhong PF, Tu JL, Zhao Y, Zhong N, Yang C, Guo L, Xia W. Photoelectrochemical oxidative C(sp 3)-H borylation of unactivated hydrocarbons. Nat Commun 2023; 14:6530. [PMID: 37845202 PMCID: PMC10579347 DOI: 10.1038/s41467-023-42264-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 10/04/2023] [Indexed: 10/18/2023] Open
Abstract
Organoboron compounds are of high significance in organic synthesis due to the unique versatility of boryl substituents to access further modifications. The high demand for the incorporation of boryl moieties into molecular structures has witnessed significant progress, particularly in the C(sp3)-H borylation of hydrocarbons. Taking advantage of special characteristics of photo/electrochemistry, we herein describe the development of an oxidative C(sp3)-H borylation reaction under metal- and oxidant-free conditions, enabled by photoelectrochemical strategy. The reaction exhibits broad substrate scope (>57 examples), and includes the use of simple alkanes, halides, silanes, ketones, esters and nitriles as viable substrates. Notably, unconventional regioselectivity of C(sp3)-H borylation is achieved, with the coupling site of C(sp3)-H borylation selectively located in the distal methyl group. Our method is operationally simple and easily scalable, and offers a feasible approach for the one-step synthesis of high-value organoboron building blocks from simple hydrocarbons, which would provide ample opportunities for drug discovery.
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Affiliation(s)
- Ping-Fu Zhong
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Jia-Lin Tu
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Yating Zhao
- College of Chemical and Material Engineering, Quzhou University, Quzhou, 324000, China
| | - Nan Zhong
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Chao Yang
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Lin Guo
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
| | - Wujiong Xia
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, China.
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27
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Li Y, Guo S, Li QH, Zheng K. Metal-free photoinduced C(sp 3)-H/C(sp 3)-H cross-coupling to access α‑tertiary amino acid derivatives. Nat Commun 2023; 14:6225. [PMID: 37802984 PMCID: PMC10558569 DOI: 10.1038/s41467-023-41956-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023] Open
Abstract
The cross-dehydrogenative coupling (CDC) reaction is the most direct and efficient method for constructing α-tertiary amino acids (ATAAs), which avoids the pre-activation of C(sp3)-H substrates. However, the use of transition metals and harsh reaction conditions are still significant challenges for these reactions that urgently require solutions. This paper presents a mild, metal-free CDC reaction for the construction of ATAAs, which is compatible with various benzyl C-H substrates, functionalized C-H substrates, and alkyl substrates, with good regioselectivity. Notably, our method exhibits excellent functional group tolerance and late-stage applicability. According to mechanistic studies, the one-step synthesized and bench-stable N-alkoxyphtalimide generates a highly electrophilic trifluoro ethoxy radical that serves as a key intermediate in the reaction process and acts as a hydrogen atom transfer reagent. Therefore, our metal-free and additive-free method offers a promising strategy for the synthesis of ATAAs under mild conditions.
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Affiliation(s)
- Yujun Li
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, PR China
| | - Shaopeng Guo
- Key Laboratory of General Chemistry of the National Ethnic Affairs Commission, College of Chemistry and Environment, Southwest Minzu University, Chengdu, PR China
| | - Qing-Han Li
- Key Laboratory of General Chemistry of the National Ethnic Affairs Commission, College of Chemistry and Environment, Southwest Minzu University, Chengdu, PR China
| | - Ke Zheng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, PR China.
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28
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Chen SJ, He CQ, Kong M, Wang J, Lin S, Krska SW, Stahl SS. Accessing three-dimensional molecular diversity through benzylic C-H cross-coupling. NATURE SYNTHESIS 2023; 2:998-1008. [PMID: 38463240 PMCID: PMC10923599 DOI: 10.1038/s44160-023-00332-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 04/25/2023] [Indexed: 03/12/2024]
Abstract
Pharmaceutical and agrochemical discovery efforts rely on robust methods for chemical synthesis that rapidly access diverse molecules1,2. Cross-coupling reactions are the most widely used synthetic methods3, but these methods typically form bonds to C(sp2)-hybridized carbon atoms (e.g., amide coupling, biaryl coupling) and lead to a prevalence of "flat" molecular structures with suboptimal physicochemical and topological properties4. Benzylic C(sp3)-H cross-coupling methods offer an appealing strategy to address this limitation by directly forming bonds to C(sp3)-hybridized carbon atoms, and emerging methods exhibit synthetic versatility that rivals conventional cross-coupling methods to access products with drug-like properties. Here, we use a virtual library of >350,000 benzylic ethers and ureas derived from benzylic C-H cross-coupling to test the widely held view that coupling at C(sp3)-hybridized carbon atoms affords products with improved three-dimensionality. The results show that the conformational rigidity of the benzylic scaffold strongly influences the product dimensionality. Products derived from flexible scaffolds often exhibit little or no improvement in three-dimensionality, unless they adopt higher energy conformations. This outcome introduces an important consideration when designing routes to topologically diverse molecular libraries. The concepts elaborated herein are validated experimentally through an informatics-guided synthesis of selected targets and the use of high-throughput experimentation to prepare a library of three-dimensional products that are broadly distributed across drug-like chemical space.
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Affiliation(s)
- Si-Jie Chen
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI, USA
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, CA, USA
| | - Cyndi Qixin He
- Department of Discovery Chemistry, Merck & Co., Inc., Kenilworth, NJ, USA
| | - May Kong
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, CA, USA
| | - Jun Wang
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, CA, USA
| | - Shishi Lin
- Department of Discovery Chemistry, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Shane W. Krska
- Department of Discovery Chemistry, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI, USA
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29
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Maity S, Lopez MA, Bates DM, Lin S, Krska SW, Stahl SS. Polar Heterobenzylic C(sp 3)-H Chlorination Pathway Enabling Efficient Diversification of Aromatic Nitrogen Heterocycles. J Am Chem Soc 2023; 145:19832-19839. [PMID: 37642292 PMCID: PMC10629438 DOI: 10.1021/jacs.3c05822] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Site-selective radical reactions of benzylic C-H bonds are now highly effective methods for C(sp3-H) functionalization and cross-coupling. The existing methods, however, are often ineffective with heterobenzylic C-H bonds in alkyl-substituted pyridines and related aromatic heterocycles that are prominently featured in pharmaceuticals and agrochemicals. Here, we report new synthetic methods that leverage polar, rather than radical, reaction pathways to enable the selective heterobenzylic C-H chlorination of 2- and 4-alkyl-substituted pyridines and other heterocycles. Catalytic activation of the substrate with trifluoromethanesulfonyl chloride promotes the formation of enamine tautomers that react readily with electrophilic chlorination reagents. The resulting heterobenzyl chlorides can be used without isolation or purification in nucleophilic coupling reactions. This chlorination-diversification sequence provides an efficient strategy to achieve heterobenzylic C-H cross-coupling with aliphatic amines and a diverse collection of azoles, among other coupling partners.
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Affiliation(s)
- Soham Maity
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Marco A. Lopez
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Desiree M. Bates
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Shishi Lin
- Discovery Chemistry, Merck & Co., Inc., 2000 Galloping Hill Road, Kenilworth, NJ 07033, United States
| | - Shane W. Krska
- Discovery Chemistry, Merck & Co., Inc., 2000 Galloping Hill Road, Kenilworth, NJ 07033, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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30
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Ruos ME, Kinney RG, Ring OT, Doyle AG. A General Photocatalytic Strategy for Nucleophilic Amination of Primary and Secondary Benzylic C-H Bonds. J Am Chem Soc 2023; 145:18487-18496. [PMID: 37565772 DOI: 10.1021/jacs.3c04912] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
We report a visible-light photoredox-catalyzed method that enables nucleophilic amination of primary and secondary benzylic C(sp3)-H bonds. A novel amidyl radical precursor and organic photocatalyst operate in tandem to transform primary and secondary benzylic C(sp3)-H bonds into carbocations via sequential hydrogen atom transfer (HAT) and oxidative radical-polar crossover. The resulting carbocation can be intercepted by a variety of N-centered nucleophiles, including nitriles (Ritter reaction), amides, carbamates, sulfonamides, and azoles, for the construction of pharmaceutically relevant C(sp3)-N bonds under unified reaction conditions. Mechanistic studies indicate that HAT is amidyl radical-mediated and that the photocatalyst operates via a reductive quenching pathway. These findings establish a mild, metal-free, and modular protocol for the rapid diversification of C(sp3)-H bonds to a library of aminated products.
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Affiliation(s)
- Madeline E Ruos
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
| | - R Garrison Kinney
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Oliver T Ring
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
- Early Chemical Development, Pharmaceutical Sciences, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, SE-431 83 Mölndal, Sweden
| | - Abigail G Doyle
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
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31
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Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
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Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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32
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Maity B, Dutta S, Cavallo L. The mechanism of visible light-induced C-C cross-coupling by C sp3-H bond activation. Chem Soc Rev 2023; 52:5373-5387. [PMID: 37464786 DOI: 10.1039/d2cs00960a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Csp3-C cross-coupling by activating Csp3-H bonds is a dream reaction for the chemical community, and visible light-induced transition metal-catalysis under mild reaction conditions is considered a powerful tool to achieve it. Advancement of this research area is still in its infancy because of the chemical and technical complexity of this catalysis. Mechanistic studies illuminating the operative reaction pathways can rationalize the increasing amount of experimental catalysis data and provide the knowledge allowing faster and rational advances in the field. This goal requires complementary experimental and theoretical mechanistic studies, as each of them is unfit to clarify the operative mechanisms alone. In this tutorial review we summarize representative experimental and computational mechanistic studies, highlighting weaknesses, strengths, and synergies between the two approaches.
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Affiliation(s)
- Bholanath Maity
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Sayan Dutta
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Luigi Cavallo
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
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33
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Joshi H, Paul D, Sathyamoorthi S. Oxidations of Alcohols, Aldehydes, and Diols Using NaBr and Selectfluor. J Org Chem 2023; 88:11240-11252. [PMID: 37490704 PMCID: PMC10804234 DOI: 10.1021/acs.joc.3c01307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
We present protocols for the oxidation of alcohols and aldehydes and for the oxidative cyclization of diols which use a combination of Selectfluor and NaBr. For most substrates, the optimal solvent system is a 1:1 mixture of CH3CN/H2O, but, in select cases, biphasic 1:1 mixtures of EtOAc/H2O or CH2Cl2/H2O are superior. This procedure is operationally simple, uses inexpensive and readily available reagents, and tolerates a variety of functional groups. Mechanistic studies suggest that the active oxidant is hypobromous acid, generated by the almost instantaneous oxidation of Br- by Selectfluor in an aqueous milieu.
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Affiliation(s)
- Harshit Joshi
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Debobrata Paul
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Shyam Sathyamoorthi
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
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34
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Lu Z, Ju M, Wang Y, Meinhardt JM, Martinez Alvarado JI, Villemure E, Terrett JA, Lin S. Regioselective aliphatic C-H functionalization using frustrated radical pairs. Nature 2023; 619:514-520. [PMID: 37407819 PMCID: PMC10530363 DOI: 10.1038/s41586-023-06131-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/25/2023] [Indexed: 07/07/2023]
Abstract
Frustrated Lewis pairs (FLPs) are well documented for the activation of small molecules such as dihydrogen and carbon dioxide1-4. Although canonical FLP chemistry is heterolytic in nature, recent work has shown that certain FLPs can undergo single-electron transfer to afford radical pairs5. Owing to steric encumbrance and/or weak bonding association, these radicals do not annihilate one another, and they have thus been named frustrated radical pairs (FRPs). Notable preliminary results suggest that FRPs may be useful reagents in chemical synthesis6-8, although their applications remain limited. Here we demonstrate that the functionalization of C(sp3)-H bonds can be accomplished using a class of FRPs generated from disilazide donors and an N-oxoammonium acceptor. Together, these species undergo single-electron transfer to generate a transient and persistent radical pair capable of cleaving unactivated C-H bonds to furnish aminoxylated products. By tuning the structure of the donor, it is possible to control regioselectivity and tailor reactivity towards tertiary, secondary or primary C-H bonds. Mechanistic studies lend strong support for the formation and involvement of radical pairs in the target reaction.
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Affiliation(s)
- Zhipeng Lu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Minsoo Ju
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Yi Wang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Jonathan M Meinhardt
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | | | - Elisia Villemure
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA, USA
| | - Jack A Terrett
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA, USA
| | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
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35
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Kim J, Kim M, Jeong J, Hong S. Unlocking the Potential of β-Fragmentation of Aminophosphoranyl Radicals for Sulfonyl Radical Reactions. J Am Chem Soc 2023. [PMID: 37339337 DOI: 10.1021/jacs.3c04112] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Exploiting β-scission in aminophosphoranyl radicals for radical-mediated transformations has been a longstanding challenge. In this study, we investigated the untapped potential of β-fragmentation in aminophosphoranyl radicals by leveraging the unique properties of the P-N bond and the substituents of P(III) reagents. Our approach carefully considers factors such as cone angle and electronic properties of phosphine and employs density functional theory (DFT) calculations to probe structural and molecular orbital influence. We successfully induced β-fragmentation through N-S bond cleavage of aminophosphoranyl radicals under visible light and mild conditions, generating a range of sulfonyl radicals derived from pyridinium salts via the photochemical activity of electron donor-acceptor (EDA) complexes. This innovative synthetic strategy exhibits broad applicability, including late-stage functionalization, and paves the way for valuable sulfonyl radical-mediated reactions, such as alkene hydrosulfonylation, difunctionalization, and pyridylic C-H sulfonylation.
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Affiliation(s)
- Jieun Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea
| | - Myojeong Kim
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea
| | - Jinwook Jeong
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea
| | - Sungwoo Hong
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea
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36
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van den Heuvel N, Mason SM, Mercado BQ, Miller SJ. Aspartyl β-Turn-Based Dirhodium(II) Metallopeptides for Benzylic C(sp 3)-H Amination: Enantioselectivity and X-ray Structural Analysis. J Am Chem Soc 2023; 145:12377-12385. [PMID: 37216431 PMCID: PMC10330621 DOI: 10.1021/jacs.3c03587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Amination of C(sp3)-H bonds is a powerful tool to introduce nitrogen into complex organic frameworks in a direct manner. Despite significant advances in catalyst design, full site- and enantiocontrol in complex molecular regimes remain elusive using established catalyst systems. To address these challenges, we herein describe a new class of peptide-based dirhodium(II) complexes derived from aspartic acid-containing β-turn-forming tetramers. This highly modular system can serve as a platform for the rapid generation of new chiral dirhodium(II) catalyst libraries, as illustrated by the facile synthesis of a series of 38 catalysts. Critically, we present the first crystal structure of a dirhodium(II) tetra-aspartate complex, which unveils retention of the β-turn conformation of the peptidyl ligand; a well-defined hydrogen-bonding network is evident, along with a near-C4 symmetry that renders the rhodium centers inequivalent. The utility of this catalyst platform is illustrated by the enantioselective amination of benzylic C(sp3)-H bonds, in which state-of-the-art levels of enantioselectivity up to 95.5:4.5 er are obtained, even for substrates that present challenges with previously reported catalyst systems. Additionally, we found these complexes to be competent catalysts for the intermolecular amination of N-alkylamides via insertion into the C(sp3)-H bond α to the amide nitrogen, yielding differentially protected 1,1-diamines. Of note, this type of insertion was also observed to occur on the amide functionalities of the catalyst itself in the absence of the substrate but did not appear to be detrimental to reaction outcomes when the substrate was present.
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Affiliation(s)
- Naudin van den Heuvel
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Savannah M. Mason
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott J. Miller
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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37
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Golden DL, Zhang C, Chen SJ, Vasilopoulos A, Guzei IA, Stahl SS. Benzylic C-H Esterification with Limiting C-H Substrate Enabled by Photochemical Redox Buffering of the Cu Catalyst. J Am Chem Soc 2023; 145:9434-9440. [PMID: 37084265 PMCID: PMC10510071 DOI: 10.1021/jacs.3c01662] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
Abstract
Copper-catalyzed radical-relay reactions provide a versatile strategy for selective C-H functionalization; however, reactions with peroxide-based oxidants often require excess C-H substrate. Here, we report a photochemical strategy to overcome this limitation by using a Cu/2,2'-biquinoline catalyst that supports benzylic C-H esterification with limiting C-H substrate. Mechanistic studies indicate that blue-light irradiation promotes carboxylate-to-copper charge transfer, reducing resting-state CuII to CuI, which activates the peroxide to generate an alkoxyl radical hydrogen-atom-transfer species. This "photochemical redox buffering" introduces a unique strategy to sustain the activity of Cu catalysts in radical-relay reactions.
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Affiliation(s)
- Dung L. Golden
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Chaofeng Zhang
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- Present Address: Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Si-Jie Chen
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- Present Address: Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, California, United States
| | - Aristidis Vasilopoulos
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- Present Address: AbbVie, Inc., 1 North Waukegan Road, North Chicago, Illinois 60064, United States
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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38
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Peng P, Zhong Y, Zhou C, Tao Y, Li D, Lu Q. Unlocking the Nucleophilicity of Strong Alkyl C-H Bonds via Cu/Cr Catalysis. ACS CENTRAL SCIENCE 2023; 9:756-762. [PMID: 37122460 PMCID: PMC10141608 DOI: 10.1021/acscentsci.2c01389] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Indexed: 05/03/2023]
Abstract
Direct functionalization of inert C-H bonds is one of the most attractive yet challenging strategies for constructing molecules in organic chemistry. Herein, we disclose an unprecedented and Earth abundant Cu/Cr catalytic system in which unreactive alkyl C-H bonds are transformed into nucleophilic alkyl-Cr(III) species at room temperature, enabling carbonyl addition reactions with strong alkyl C-H bonds. Various aryl alkyl alcohols are furnished under mild reaction conditions even on a gram scale. Moreover, this new radical-to-polar crossover approach is further applied to the 1,1-difunctionalization of aldehydes with alkanes and different nucleophiles. Mechanistic investigations reveal that the aldehyde not only acts as a reactant but also serves as a photosensitizer to recycle the Cu and Cr catalysts.
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Affiliation(s)
- Pan Peng
- The
Institute for Advanced Studies (IAS), Wuhan
University, Wuhan 430072, P. R. China
| | - Yifan Zhong
- The
Institute for Advanced Studies (IAS), Wuhan
University, Wuhan 430072, P. R. China
| | - Cong Zhou
- The
Institute for Advanced Studies (IAS), Wuhan
University, Wuhan 430072, P. R. China
| | - Yongsheng Tao
- The
Institute for Advanced Studies (IAS), Wuhan
University, Wuhan 430072, P. R. China
| | - Dandan Li
- Key
Laboratory of Micro-Nano Materials for Energy Storage and Conversion
of Henan Province, Institute of Surface Micro and Nano Materials,
College of Chemical and Materials Engineering, Xuchang University, Henan 461000, P. R. China
| | - Qingquan Lu
- The
Institute for Advanced Studies (IAS), Wuhan
University, Wuhan 430072, P. R. China
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39
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Chen X, Lian Z, Kramer S. Enantioselective Intermolecular Radical Amidation and Amination of Benzylic C-H Bonds via Dual Copper and Photocatalysis. Angew Chem Int Ed Engl 2023; 62:e202217638. [PMID: 36721305 DOI: 10.1002/anie.202217638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/23/2023] [Accepted: 01/31/2023] [Indexed: 02/02/2023]
Abstract
A method for direct access to enantioenriched benzylic amides and carbamate-protected primary benzylamines by C-H functionalization is reported. The C-H substrate is used as limiting reagent with only a small excess of the unactivated amide or carbamate nucleophile. The enantioselective intermolecular dehydrogenative C-N bond formation is enabled by a combination of a chiral copper catalyst, a photocatalyst, and an oxidant, and it takes place under mild conditions, which allow for a broad substrate scope. The method is compatible with late-stage C-H functionalization, and it provides easy access to 15 N-labeled amides and amines starting from cheap 15 NH4 Cl.
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Affiliation(s)
- Xuemeng Chen
- Department of Chemistry, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Zhong Lian
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital and West China School of Pharmacy, Sichuan University, China
| | - Søren Kramer
- Department of Chemistry, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
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40
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Ji AY, Thirupathi A, Hwang JY, Kim Y, Han G, Ahn KH, Kang K, Kang EJ. Iron Catalysis of C(sp 3)-H Azidation Using a Heteroarene Radical Cation Strategy. Org Lett 2023; 25:1541-1546. [PMID: 36856660 DOI: 10.1021/acs.orglett.3c00330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
The FeIII(phen)3 catalysis of the benzylic C(sp3)-H azidation of indoles has been investigated. The Fe(III) complex can selectively oxidize indoles to form arene radical cations, which are transformed into benzylic C(sp3) radical intermediates. This strategy exhibits a difference in reactivity between N-heteroarenes and benzene, which is difficult to achieve via direct hydrogen abstraction approaches. Various biorelevant azide precursors were constructed, highlighting the utility of this mild first-row transition-metal catalyst system.
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Affiliation(s)
- A Young Ji
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Annaram Thirupathi
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Joon Young Hwang
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Yuri Kim
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Gyuri Han
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Kwang-Hyun Ahn
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Kyungtae Kang
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Eun Joo Kang
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
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41
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Yuan CH, Wang XX, Jiao L. Ligand-Enabled Palladium(II)-Catalyzed Enantioselective β-C(sp 3 )-H Arylation of Aliphatic Tertiary Amides. Angew Chem Int Ed Engl 2023; 62:e202300854. [PMID: 36851818 DOI: 10.1002/anie.202300854] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/23/2023] [Accepted: 02/27/2023] [Indexed: 03/01/2023]
Abstract
Amide is one of the most widespread functional groups in organic and bioorganic chemistry, and it would be valuable to achieve stereoselective C(sp3 )-H functionalization in amide molecules. Palladium(II) catalysis has been prevalently used in the C-H activation chemistry in the past decades, however, due to the weakly-coordinating feature of simple amides, it is challenging to achieve their direct C(sp3 )-H functionalization with enantiocontrol by PdII catalysis. Our group has developed sulfoxide-2-hydroxypridine (SOHP) ligands, which exhibited remarkable activity in Pd-catalyzed C(sp2 )-H activation. In this work, we demonstrate that chiral SOHP ligands served as an ideal solution to enantioselective C(sp3 )-H activation in simple amides. Herein, we report an efficient asymmetric PdII /SOHP-catalyzed β-C(sp3 )-H arylation of aliphatic tertiary amides, in which the SOHP ligand plays a key role in the stereoselective C-H deprotonation-metalation step.
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Affiliation(s)
- Chen-Hui Yuan
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Xiao-Xia Wang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Lei Jiao
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
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42
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Liu X, Chu X. Metal-Free Synthesis of Functionalized Quinolines from 2-Styrylanilines and 2-Methylbenzothiazoles/2-Methylquinolines. ACS OMEGA 2023; 8:6940-6944. [PMID: 36844512 PMCID: PMC9948197 DOI: 10.1021/acsomega.2c07736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Abstract
A facile functionalization of C(sp3)-H bonds and tandem cyclization strategy to synthesize quinoline derivatives from 2-methylbenzothiazoles or 2-methylquinolines and 2-styrylanilines has been developed. This work avoids the requirement for transition metals, offering a mild approach to activation of C(sp3)-H bonds and formation of new C-C and C-N bonds. This strategy features excellent functional group tolerance and scaled-up synthetic capability, thus providing an efficient and environmentally friendly access to medicinally valuable quinolines.
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43
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Abstract
The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C-H functionalization approaches that make use of low energy photons as a controllable energy source. Compared to traditional late-stage functionalization strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- and chemoselectivities. Merging the compelling benefits of photocatalysis with the late-stage functionalization workflow offers a potentially unmatched arsenal to tackle drug development campaigns and beyond. This Review highlights the photocatalytic late-stage C-H functionalization strategies of small-molecule drugs, agrochemicals, and natural products, classified according to the targeted C-H bond and the newly formed one. Emphasis is devoted to identifying, describing, and comparing the main mechanistic scenarios. The Review draws a critical comparison between established ionic chemistry and photocatalyzed radical-based manifolds. The Review aims to establish the current state-of-the-art and illustrate the key unsolved challenges to be addressed in the future. The authors aim to introduce the general readership to the main approaches toward photocatalytic late-stage C-H functionalization, and specialist practitioners to the critical evaluation of the current methodologies, potential for improvement, and future uncharted directions.
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Affiliation(s)
- Peter Bellotti
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Huan-Ming Huang
- School of Physical Science and Technology, ShanghaiTech University, 201210Shanghai, China
| | - Teresa Faber
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
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44
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Ding D, Fan LF, Han ZY, Wang PS. Redox-Neutral 1,4-Dicarbonfunctionalization of 1,3-Butadiene by Merging Photoredox and Nickel Catalysis. Org Lett 2023; 25:210-214. [PMID: 36534618 DOI: 10.1021/acs.orglett.2c04060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The diverse functionalization of 1,3-butadiene provides wide applicability toward the synthesis of abundant and useful allylic compounds. Here, we describe a three-component and redox-neutral assembly of readily available C═X compounds, 1,3-butadiene, and various nucleophiles by merging photoredox and nickel catalysis, enabling the rapid synthesis of structurally diverse homoallyl amines and homoallylic alcohols.
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Affiliation(s)
- Du Ding
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Lian-Feng Fan
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Zhi-Yong Han
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Pu-Sheng Wang
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
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45
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Site- and enantioselective cross-coupling of saturated N-heterocycles with carboxylic acids by cooperative Ni/photoredox catalysis. Nat Commun 2023; 14:125. [PMID: 36624097 PMCID: PMC9829739 DOI: 10.1038/s41467-023-35800-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 01/02/2023] [Indexed: 01/11/2023] Open
Abstract
Site- and enantioselective cross-coupling of saturated N-heterocycles and carboxylic acids-two of the most abundant and versatile functionalities-to form pharmaceutically relevant α-acylated amine derivatives remains a major challenge in organic synthesis. Here, we report a general strategy for the highly site- and enantioselective α-acylation of saturated N-heterocycles with in situ-activated carboxylic acids. This modular approach exploits the hydrogen-atom-transfer reactivity of photocatalytically generated chlorine radicals in combination with asymmetric nickel catalysis to selectively functionalize cyclic α-amino C-H bonds in the presence of benzylic, allylic, acyclic α-amino, and α-oxy methylene groups. The mild and scalable protocol requires no organometallic reagents, displays excellent chemo-, site- and enantioselectivity, and is amenable to late-stage diversification, including a modular synthesis of previously inaccessible Taxol derivatives. Mechanistic studies highlight the exceptional versatility of the chiral nickel catalyst in orchestrating (i) catalytic chlorine elimination, (ii) alkyl radical capture, (iii) cross-coupling, and (iv) asymmetric induction.
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46
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He XX, Chang HH, Zhao YX, Li XJ, Liu SA, Zang ZL, Zhou CH, Cai GX. CuCl 2 -Catalyzed α-Chloroketonation of Aromatic Alkenes via Visible-Light-Induced LMCT. Chem Asian J 2023; 18:e202200954. [PMID: 36378015 DOI: 10.1002/asia.202200954] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/02/2022] [Indexed: 11/17/2022]
Abstract
Here we report a copper-catalyzed protocol for the synthesis of α-chloroketones from aromatic alkenes including electron-deficient olefins under visible-light irradiation. Preliminary mechanistic studies show that the peroxo Cu(II) species is the key intermediate and hydroperoxyl (HOO⋅) and chlorine (Cl⋅) radicals can be generated by ligand-to-metal charge transfer (LMCT).
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Affiliation(s)
- Xing-Xian He
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Huan-Huan Chang
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Ying-Xue Zhao
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Xiang-Jie Li
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Sheng-An Liu
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Zhong-Lin Zang
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Cheng-He Zhou
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
| | - Gui-Xin Cai
- Institute of Bioorganic & Medicinal Chemistry, School of Chemistry, Chemical Engineering, Key Laboratory of Quality and Safety Control for Citrus Fruits, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing, 400715, P. R. China
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47
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Chen J, Wang H, Day CS, Martin R. Nickel-Catalyzed Site-Selective Intermolecular C(sp 3 )-H Amidation. Angew Chem Int Ed Engl 2022; 61:e202212983. [PMID: 36254803 DOI: 10.1002/anie.202212983] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Indexed: 11/06/2022]
Abstract
A nickel-catalyzed site-selective intermolecular amidation of saturated C(sp3 )-H bonds is reported. This mild protocol exhibits a predictable reactivity pattern to incorporate amide functions at C(sp3 )-H sites adjacent to nitrogen and oxygen atoms in either cyclic or acyclic frameworks, thus offering a complementary reactivity profile to existing oxidative-type processes or metal-catalyzed C(sp3 )-N bond-forming reactions operating via two-electron manifolds.
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Affiliation(s)
- Jinhong Chen
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain
- Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, c/Marcel ⋅ lí Domingo, 1, 43007, Tarragona, Spain
| | - Hao Wang
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain
- Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, c/Marcel ⋅ lí Domingo, 1, 43007, Tarragona, Spain
| | - Craig S Day
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain
- Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, c/Marcel ⋅ lí Domingo, 1, 43007, Tarragona, Spain
| | - Ruben Martin
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain
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48
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Paveliev SA, Segida OO, Mulina OM, Krylov IB, Terent’ev AO. Decatungstate-Catalyzed Photochemical Synthesis of Enaminones from Vinyl Azides and Aldehydes. Org Lett 2022; 24:8942-8947. [DOI: 10.1021/acs.orglett.2c03364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Stanislav A. Paveliev
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Oleg O. Segida
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Olga M. Mulina
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Igor B. Krylov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Alexander O. Terent’ev
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
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49
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Fan W, Zhao X, Deng Y, Chen P, Wang F, Liu G. Electrophotocatalytic Decoupled Radical Relay Enables Highly Efficient and Enantioselective Benzylic C–H Functionalization. J Am Chem Soc 2022; 144:21674-21682. [DOI: 10.1021/jacs.2c09366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Wenzheng Fan
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Xueyao Zhao
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yunshun Deng
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Pinhong Chen
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Fei Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Guosheng Liu
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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50
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Selective functionalization of benzylic C(sp3)–H bonds to synthesize complex molecules. Chem 2022. [DOI: 10.1016/j.chempr.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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