1
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Atkins AP, Dean AC, Lennox AJJ. Benzylic C(sp 3)-H fluorination. Beilstein J Org Chem 2024; 20:1527-1547. [PMID: 39015617 PMCID: PMC11250007 DOI: 10.3762/bjoc.20.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/26/2024] [Indexed: 07/18/2024] Open
Abstract
The selective fluorination of C(sp3)-H bonds is an attractive target, particularly for pharmaceutical and agrochemical applications. Consequently, over recent years much attention has been focused on C(sp3)-H fluorination, and several methods that are selective for benzylic C-H bonds have been reported. These protocols operate via several distinct mechanistic pathways and involve a variety of fluorine sources with distinct reactivity profiles. This review aims to give context to these transformations and strategies, highlighting the different tactics to achieve fluorination of benzylic C-H bonds.
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Affiliation(s)
| | - Alice C Dean
- University of Bristol, School of Chemistry, Bristol, BS8 1TS, U.K.
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2
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Kitahara T, Tagami Y, Haga Y, Fustero S, Sugiishi T, Amii H. Alkylation and silylation of α-fluorobenzyl anion intermediates. Org Biomol Chem 2023; 21:9210-9215. [PMID: 37961788 DOI: 10.1039/d3ob01586f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Simple α-fluorobenzyl anions reacted with electrophiles such as non-activated alkyl halides and chlorotrimethylsilane. Upon treatment with LTMP as the base, fluoromethylbenzenes took part in the formation of α-monofluorobenzyl anions without stabilizing o-substituents. Furthermore, the resulting α-silyl fluoromethylbenzenes reacted with electrophiles such as acetophenone and benzaldehyde in the presence of cesium fluoride to form α-fluorobenzylated alcohols.
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Affiliation(s)
- Taku Kitahara
- Division of Molecular Science, Graduate School of Science and Technology, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
| | - Yuta Tagami
- Division of Molecular Science, Graduate School of Science and Technology, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
| | - Yuto Haga
- Division of Molecular Science, Graduate School of Science and Technology, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
| | - Santos Fustero
- Departamento de Química Orgánica, Facultad de Farmacia, Universitat de València, Vicente Andrés Estelles s/n, C.P.: 46100 Burjassot, Valencia, Spain
| | - Tsuyuka Sugiishi
- Division of Molecular Science, Graduate School of Science and Technology, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
| | - Hideki Amii
- Division of Molecular Science, Graduate School of Science and Technology, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
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3
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Yuan Z, Britton R. Development and application of decatungstate catalyzed C-H 18F- and 19F-fluorination, fluoroalkylation and beyond. Chem Sci 2023; 14:12883-12897. [PMID: 38023504 PMCID: PMC10664588 DOI: 10.1039/d3sc04027e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
Over the past few decades, photocatalytic C-H functionalization reactions have received increasing attention due to the often mild reaction conditions and complementary selectivities to conventional functionalization processes. Now, photocatalytic C-H functionalization is a widely employed tool, supporting activities ranging from complex molecule synthesis to late-stage structure-activity relationship studies. In this perspective, we will discuss our efforts in developing a photocatalytic decatungstate catalyzed C-H fluorination reaction as well as its practical application realized through collaborations with industry partners at Hoffmann-La Roche and Merck, and extension to radiofluorination with radiopharmaceutical chemists and imaging experts at TRIUMF and the BC Cancer Agency. Importantly, we feel that our efforts address a question of utility posed by Professor Tobias Ritter in "Late-Stage Fluorination: Fancy Novelty or Useful Tool?" (ACIE, 2015, 54, 3216). In addition, we will discuss decatungstate catalyzed C-H fluoroalkylation and the interesting electrostatic effects observed in decatungstate-catalyzed C-H functionalization. We hope this perspective will inspire other researchers to explore the use of decatungstate for the purposes of photocatalytic C-H functionalization and further advance the exploitation of electrostatic effects for both rate acceleration and directing effects in these reactions.
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Affiliation(s)
- Zheliang Yuan
- Department of Chemistry, Simon Fraser University Burnaby British Columbia V5A 1S2 Canada
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University Jinhua Zhejiang 321004 China
| | - Robert Britton
- Department of Chemistry, Simon Fraser University Burnaby British Columbia V5A 1S2 Canada
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4
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Wang X, Zhang X, Xue L, Wang Q, You F, Dai L, Wu J, Kramer S, Lian Z. Mechanochemical Synthesis of Aryl Fluorides by Using Ball Milling and a Piezoelectric Material as the Redox Catalyst. Angew Chem Int Ed Engl 2023; 62:e202307054. [PMID: 37523257 DOI: 10.1002/anie.202307054] [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: 05/19/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/02/2023]
Abstract
Aryl fluorides are important structural motifs in many pharmaceuticals. Although the Balz-Schiemann reaction provides an entry to aryl fluorides from aryldiazonium tetrafluoroborates, it suffers from drawbacks such as long reaction time, high temperature, toxic solvent, toxic gas release, and low functional group tolerance. Here, we describe a general method for the synthesis of aryl fluorides from aryldiazonium tetrafluoroborates using a piezoelectric material as redox catalyst under ball milling conditions in the presence of Selectfluor. This approach effectively addresses the aforementioned limitations. Furthermore, the piezoelectric material can be recycled multiple times. Mechanistic investigations indicate that this fluorination reaction may proceed via a radical pathway, and Selectfluor plays a dual role as both a source of fluorine and a terminal reductant.
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Affiliation(s)
- Xiaohong Wang
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Xuemei Zhang
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Li Xue
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Qingqing Wang
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Fengzhi You
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Lunzhi Dai
- Department of Dermatology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Jiagang Wu
- Department of Materials Science, Sichuan University, 610064, Chengdu, China
| | - Søren Kramer
- 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, Sichuan University, 610041, Chengdu, P. R. China
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5
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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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6
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Roy S, Panja S, Sahoo SR, Chatterjee S, Maiti D. Enroute sustainability: metal free C-H bond functionalisation. Chem Soc Rev 2023; 52:2391-2479. [PMID: 36924227 DOI: 10.1039/d0cs01466d] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
The term "C-H functionalisation" incorporates C-H activation followed by its transformation. In a single line, this can be defined as the conversion of carbon-hydrogen bonds into carbon-carbon or carbon-heteroatom bonds. The catalytic functionalisation of C-H bonds using transition metals has emerged as an atom-economical technique to engender new bonds without activated precursors which can be considered as a major drawback while attempting large-scale synthesis. Replacing the transition-metal-catalysed approach with a metal-free strategy significantly offers an alternative route that is not only inexpensive but also environmentally benign to functionalize C-H bonds. Recently metal free synthetic approaches have been flourishing to functionalize C-H bonds, motivated by the search for greener, cost-effective, and non-toxic catalysts. In this review, we will highlight the comprehensive and up-to-date discussion on recent examples of ground-breaking research on green and sustainable metal-free C-H bond functionalisation.
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Affiliation(s)
- Sayan Roy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
| | - Subir Panja
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
| | - Sumeet Ranjan Sahoo
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
| | - Sagnik Chatterjee
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
| | - Debabrata Maiti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India. .,Department of Interdisciplinary Program in Climate Studies, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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7
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Yamashita K, Fujiwara Y, Hamashima Y. Amide-Ligand-Promoted Silver-Catalyzed C-H Fluorination via Radical/Polar Crossover. J Org Chem 2023; 88:1865-1874. [PMID: 36688540 DOI: 10.1021/acs.joc.2c02575] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We describe an efficient method for benzylic C-H fluorination via sequential hydrogen-atom transfer (HAT) and oxidative radical-polar crossover utilizing the Ag(I)/Selectfluor system. Amide ligands, such as benzamide and sulfonamide, substantially facilitate the processes leading to a carbocation intermediate, which subsequently reacts with nucleophilic fluorinating reagent to form a C-F bond. This protocol is applicable to the fluorination of all 1°, 2°, and 3° C-H bonds as well as to late-stage C-H fluorination of bioactive molecules.
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Affiliation(s)
- Kenji Yamashita
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Yuki Fujiwara
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Yoshitaka Hamashima
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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8
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Hintz H, Bower J, Tang J, LaLama M, Sevov C, Zhang S. Copper-Catalyzed Electrochemical C-H Fluorination. CHEM CATALYSIS 2023; 3:100491. [PMID: 36743279 PMCID: PMC9894310 DOI: 10.1016/j.checat.2022.100491] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We report the systematic development of an electrooxidative methodology that translates stoichiometric C-H fluorination reactivity of an isolable CuIII fluoride complex into a catalytic process. The critical challenges of electrocatalysis with a highly reactive CuIII species were addressed by the judicious selection of electrolyte, F- source, and sacrificial electron acceptor. Catalyst-controlled C-H fluorination occurs with a preference for hydridic C-H bonds with high bond dissociation energies over weaker but less hydridic C-H bonds. The selectivity is driven by an oxidative asynchronous proton-coupled elelctron transfer (PCET) at an electrophilic CuIII-F complex. We further demonstrate that the asynchronicity factor of hydrogen atom transfer η can be used as a guideline to rationalize the selectivity of C-H fluorination.
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Affiliation(s)
- Heather Hintz
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Jamey Bower
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Jinghua Tang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Matthew LaLama
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Christo Sevov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
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9
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Stangier M, Scheremetjew A, Ackermann L. Chemo- and Site-Selective Electro-Oxidative Alkane Fluorination by C(sp 3 )-H Cleavage. Chemistry 2022; 28:e202201654. [PMID: 35844078 PMCID: PMC9804291 DOI: 10.1002/chem.202201654] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Indexed: 01/05/2023]
Abstract
Electrochemical fluorinations of C(sp3 )-H bonds with a nucleophilic fluoride source have been accomplished in a chemo- and site-selective fashion, avoiding the use of electrophilic F+ sources and stoichiometric oxidants. The introduced metal-free strategy exhibits high functional group tolerance, setting the stage for late-stage fluorinations of biorelevant motifs. The synthetic utility of the C(sp3 )-H fluorination was reflected by subsequent one-pot arylation of the generated benzylic fluorides.
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Affiliation(s)
- Maximilian Stangier
- Institut für Organische und Biomolekulare Chemie Wöhler Research Institute for Sustainable Chemistry (WISCh)Georg-August-Universität GöttingenTammannstrasse 237077GöttingenGermany
| | - Alexej Scheremetjew
- Institut für Organische und Biomolekulare Chemie Wöhler Research Institute for Sustainable Chemistry (WISCh)Georg-August-Universität GöttingenTammannstrasse 237077GöttingenGermany
| | - Lutz Ackermann
- Institut für Organische und Biomolekulare Chemie Wöhler Research Institute for Sustainable Chemistry (WISCh)Georg-August-Universität GöttingenTammannstrasse 237077GöttingenGermany
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10
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Xia XF, Huang Q, Sun TY, Jiang Y, Ran G. Catalytic Desaturation and β-Fluorination of Aliphatic Amides Enabled by an Oxidative-Promoted Bond Destabilization. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiao-Feng Xia
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu214122, China
| | - Quan Huang
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu214122, China
| | - Tian-Yu Sun
- Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen518132, China
| | - Yuqin Jiang
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang453007, China
| | - Guoxia Ran
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu214122, China
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11
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Liu XH, Yu HY, Huang JY, Su JH, Xue C, Zhou XT, He YR, He Q, Xu DJ, Xiong C, Ji HB. Biomimetic catalytic aerobic oxidation of C-sp(3)-H bonds under mild conditions using galactose oxidase model compound Cu IIL. Chem Sci 2022; 13:9560-9568. [PMID: 36091900 PMCID: PMC9400635 DOI: 10.1039/d2sc02606f] [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: 05/10/2022] [Accepted: 07/28/2022] [Indexed: 11/21/2022] Open
Abstract
Developing highly efficient catalytic protocols for C-sp(3)-H bond aerobic oxidation under mild conditions is a long-desired goal of chemists. Inspired by nature, a biomimetic approach for the aerobic oxidation of C-sp(3)-H by galactose oxidase model compound CuIIL and NHPI (N-hydroxyphthalimide) was developed. The CuIIL-NHPI system exhibited excellent performance in the oxidation of C-sp(3)-H bonds to ketones, especially for light alkanes. The biomimetic catalytic protocol had a broad substrate scope. Mechanistic studies revealed that the CuI-radical intermediate species generated from the intramolecular redox process of CuIILH2 was critical for O2 activation. Kinetic experiments showed that the activation of NHPI was the rate-determining step. Furthermore, activation of NHPI in the CuIIL-NHPI system was demonstrated by time-resolved EPR results. The persistent PINO (phthalimide-N-oxyl) radical mechanism for the aerobic oxidation of C-sp(3)-H bond was demonstrated.
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Affiliation(s)
- Xiao-Hui Liu
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Hai-Yang Yu
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Jia-Ying Huang
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Ji-Hu Su
- CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China Hefei 230026 China
| | - Can Xue
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Xian-Tai Zhou
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Yao-Rong He
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
| | - Qian He
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
| | - De-Jing Xu
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University Zhuhai 519082 China
| | - Chao Xiong
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
| | - Hong-Bing Ji
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
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12
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Madani A, Anghileri L, Heydenreich M, Möller HM, Pieber B. Benzylic Fluorination Induced by a Charge-Transfer Complex with a Solvent-Dependent Selectivity Switch. Org Lett 2022; 24:5376-5380. [PMID: 35848228 PMCID: PMC9344467 DOI: 10.1021/acs.orglett.2c02050] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
![]()
We present a divergent strategy for the fluorination
of phenylacetic
acid derivatives that is induced by a charge-transfer complex between
Selectfluor and 4-(dimethylamino)pyridine. A comprehensive investigation
of the conditions revealed a critical role of the solvent on the reaction
outcome. In the presence of water, decarboxylative fluorination through
a single-electron oxidation is dominant. Non-aqueous conditions result
in the clean formation of α-fluoro-α-arylcarboxylic acids.
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Affiliation(s)
- Amiera Madani
- Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.,Department of Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Lucia Anghileri
- Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.,Department of Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Matthias Heydenreich
- Institute of Chemistry/Analytical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Heiko M Möller
- Institute of Chemistry/Analytical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Bartholomäus Pieber
- Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
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13
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Min S, Park B, Nedsaengtip J, Hyeok Hong S. Mechanochemical Direct Fluorination of Unactivated C(
sp
3
)−H Bonds. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sehye Min
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Beomsoon Park
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Jantakan Nedsaengtip
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Soon Hyeok Hong
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
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14
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Harry SA, Xiang MR, Holt E, Zhu A, Ghorbani F, Patel D, Lectka T. Hydroxy-directed fluorination of remote unactivated C(sp 3)–H bonds: a new age of diastereoselective radical fluorination. Chem Sci 2022; 13:7007-7013. [PMID: 35774162 PMCID: PMC9200124 DOI: 10.1039/d2sc01907h] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 05/02/2022] [Indexed: 11/23/2022] Open
Abstract
We report a photochemically induced, hydroxy-directed fluorination that addresses the prevailing challenge of high diastereoselectivity in this burgeoning field. Numerous simple and complex motifs showcase a spectrum of regio- and stereochemical outcomes based on the configuration of the hydroxy group. Notable examples include a long-sought switch in the selectivity of the refractory sclareolide core, an override of benzylic fluorination, and a rare case of 3,3′-difluorination. Furthermore, calculations illuminate a low barrier transition state for fluorination, supporting our notion that alcohols are engaged in coordinated reagent direction. A hydrogen bonding interaction between the innate hydroxy directing group and fluorine is also highlighted for several substrates with 19F–1H HOESY experiments, calculations, and more. We report a photochemical, hydroxy-directed fluorination that addresses the prevailing challenge of high diastereoselectivity. Numerous motifs showcase a range of regio- and stereochemical outcomes based on the configuration of the hydroxy group.![]()
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Affiliation(s)
- Stefan Andrew Harry
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Michael Richard Xiang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Eric Holt
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Andrea Zhu
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Fereshte Ghorbani
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Dhaval Patel
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
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15
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16
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Abstract
The fields of C-H functionalization and photoredox catalysis have garnered enormous interest and utility in the past several decades. Many different scientific disciplines have relied on C-H functionalization and photoredox strategies including natural product synthesis, drug discovery, radiolabeling, bioconjugation, materials, and fine chemical synthesis. In this Review, we highlight the use of photoredox catalysis in C-H functionalization reactions. We separate the review into inorganic/organometallic photoredox catalysts and organic-based photoredox catalytic systems. Further subdivision by reaction class-either sp2 or sp3 C-H functionalization-lends perspective and tactical strategies for use of these methods in synthetic applications.
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Affiliation(s)
- Natalie Holmberg-Douglas
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - David A Nicewicz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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17
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Chen H, Wang L, Xu S, Liu X, He Q, Song L, Ji H. Selective Functionalization of Hydrocarbons Using a ppm Bioinspired Molecular Tweezer via Proton-Coupled Electron Transfer. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01350] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Hongyu Chen
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Lingling Wang
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, China
| | - Sheng Xu
- Fine Chemical Industry Research Institute, School of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, China
| | - Xiaohui Liu
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Qian He
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Lijuan Song
- School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055 China
- Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Hongbing Ji
- Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
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18
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Deng Z, Zhao Z, He G, Chen G. Photoredox-Mediated Mono- and Difluorination of Remote Unactivated Methylene C(sp 3)-H Bonds of N-Alkyl Sulfonamides. Org Lett 2021; 23:3631-3635. [PMID: 33881874 DOI: 10.1021/acs.orglett.1c01020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A photoredox-mediated δ-C(sp3)-H fluorination of sulfonyl-protected primary alkylamines with Selectfluor is developed. The reaction can proceed in excellent monofluorination selectivity for amine substrates without α substituent. For α-substituted substrates, a slightly modified reaction conditions with two rounds of operation gives the δ,δ-difluorination products in good yield. Mechanistic studies suggest SET oxidation of sulfonamide group directly generates the key sulfonamide N radical intermediate, which triggers a 1,5-HAT process to form the δ alkyl radical.
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Affiliation(s)
- Zhiqiang Deng
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Zhenxiang Zhao
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Gang He
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Gong Chen
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
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19
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Liu Z, Wang Y, Huo J, Li XJ, Li S, Song X. Selectfluor-Promoted Intramolecular N-S Bond Formation of α-Carbamoyl Ketene Dithioacetals in the Presence of Water: Synthesis of Multifunctionalized Isothiazolones. J Org Chem 2021; 86:5506-5517. [PMID: 33797258 DOI: 10.1021/acs.joc.0c03036] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A practical and efficient protocol toward fully substituted isothiazolones through Selectfluor-mediated intramolecular oxidative annulation of α-carbamoyl ketene dithioacetals has been developed in the presence of H2O and metal-free conditions. Notably, the experimental results reveal that H2O was crucial to the formation of new N-S bonds and the elimination of alkyl group from the sulfur atom. This protocol provides readily prepared substrates and possesses good functional group tolerance, mild reaction conditions, and operational simplicity, which provides potential access to applications in the pharmaceutical chemistry.
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Affiliation(s)
- Zheng Liu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
| | - Youkun Wang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
| | - Jianfeng Huo
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
| | - Xiao-Jun Li
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
| | - Shengnan Li
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
| | - Xiaoning Song
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China
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20
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Aguilar Troyano FJ, Merkens K, Anwar K, Gómez‐Suárez A. Radical-Based Synthesis and Modification of Amino Acids. Angew Chem Int Ed Engl 2021; 60:1098-1115. [PMID: 32841470 PMCID: PMC7820943 DOI: 10.1002/anie.202010157] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Indexed: 12/30/2022]
Abstract
Amino acids (AAs) are key structural motifs with widespread applications in organic synthesis, biochemistry, and material sciences. Recently, with the development of milder and more versatile radical-based procedures, the use of strategies relying on radical chemistry for the synthesis and modification of AAs has gained increased attention, as they allow rapid access to libraries of novel unnatural AAs containing a wide range of structural motifs. In this Minireview, we provide a broad overview of the advancements made in this field during the last decade, focusing on methods for the de novo synthesis of α-, β-, and γ-AAs, as well as for the selective derivatisation of canonical and non-canonical α-AAs.
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Affiliation(s)
| | - Kay Merkens
- Organic ChemistryBergische Universität WuppertalGaussstrasse 2042119WuppertalGermany
| | - Khadijah Anwar
- Organic ChemistryBergische Universität WuppertalGaussstrasse 2042119WuppertalGermany
| | - Adrián Gómez‐Suárez
- Organic ChemistryBergische Universität WuppertalGaussstrasse 2042119WuppertalGermany
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21
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Barday M, Blieck R, Ruyet L, Besset T. Remote trifluoromethylthiolation of alcohols under visible light. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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22
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Zarate C, Ardolino M, Morriello GJ, Logan KM, Kaplan WP, Torres L, Li D, Chen M, Li H, Su J, Fuller P, Maddess ML, Song ZJ. Development of Scalable Routes to 1-Bicyclo[1.1.1]pentylpyrazoles. Org Process Res Dev 2020. [DOI: 10.1021/acs.oprd.0c00446] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Cayetana Zarate
- Department of Process Research and Development, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Michael Ardolino
- Department of Process Research and Development, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Gregori J. Morriello
- Department of Discovery Chemistry, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Kaitlyn M. Logan
- Department of Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - William P. Kaplan
- Department of Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Luis Torres
- Department of Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Derun Li
- Department of Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Meng Chen
- WuXi AppTec (Tianjin), Chemistry Service Unit, Tianjin 300457, China
| | - Hongming Li
- Department of Process Research and Development, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Jing Su
- Department of Discovery Chemistry, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Peter Fuller
- Department of Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Matthew L. Maddess
- Department of Process Research and Development, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Zhiguo Jake Song
- Department of Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
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23
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24
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Yakubov S, Barham JP. Photosensitized direct C-H fluorination and trifluoromethylation in organic synthesis. Beilstein J Org Chem 2020; 16:2151-2192. [PMID: 32952732 PMCID: PMC7476599 DOI: 10.3762/bjoc.16.183] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022] Open
Abstract
The importance of fluorinated products in pharmaceutical and medicinal chemistry has necessitated the development of synthetic fluorination methods, of which direct C-H fluorination is among the most powerful. Despite the challenges and limitations associated with the direct fluorination of unactivated C-H bonds, appreciable advancements in manipulating the selectivity and reactivity have been made, especially via transition metal catalysis and photochemistry. Where transition metal catalysis provides one strategy for C-H bond activation, transition-metal-free photochemical C-H fluorination can provide a complementary selectivity via a radical mechanism that proceeds under milder conditions than thermal radical activation methods. One exciting development in C-F bond formation is the use of small-molecule photosensitizers, allowing the reactions i) to proceed under mild conditions, ii) to be user-friendly, iii) to be cost-effective and iv) to be more amenable to scalability than typical photoredox-catalyzed methods. In this review, we highlight photosensitized C-H fluorination as a recent strategy for the direct and remote activation of C-H (especially C(sp3)-H) bonds. To guide the readers, we present the developing mechanistic understandings of these reactions and exemplify concepts to assist the future planning of reactions.
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Affiliation(s)
- Shahboz Yakubov
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
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25
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Ghorbani F, Harry SA, Capilato JN, Pitts CR, Joram J, Peters GN, Tovar JD, Smajlagic I, Siegler MA, Dudding T, Lectka T. Carbonyl-Directed Aliphatic Fluorination: A Special Type of Hydrogen Atom Transfer Beats Out Norrish II. J Am Chem Soc 2020; 142:14710-14724. [PMID: 32786786 DOI: 10.1021/jacs.0c07004] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recently, our group reported that enone and ketone functional groups, upon photoexcitation, can direct site-selective sp3 C-H fluorination in terpenoid derivatives. How this transformation actually occurred remained mysterious, as a significant number of mechanistic possibilities came to mind. Herein, we report a comprehensive study describing the reaction mechanism through kinetic studies, isotope-labeling experiments, 19F NMR, electrochemical studies, synthetic probes, and computational experiments. To our surprise, the mechanism suggests intermolecular hydrogen atom transfer (HAT) chemistry is at play, rather than classical Norrish hydrogen atom abstraction as initially conceived. What is more, we discovered a unique role for photopromoters such as benzil and related compounds that necessitates their chemical transformation through fluorination in order to be effective. Our findings provide documentation of an unusual form of directed HAT and are of crucial importance for defining the necessary parameters for the development of future methods.
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Affiliation(s)
- Fereshte Ghorbani
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Stefan Andrew Harry
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Joseph N Capilato
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Cody Ross Pitts
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Jacob Joram
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Garvin N Peters
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - John D Tovar
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Ivor Smajlagic
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2S 3A1, Canada
| | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Travis Dudding
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2S 3A1, Canada
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
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26
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Bafaluy D, Georgieva Z, Muñiz K. Iodine Catalysis for C(sp 3 )-H Fluorination with a Nucleophilic Fluorine Source. Angew Chem Int Ed Engl 2020; 59:14241-14245. [PMID: 32421217 DOI: 10.1002/anie.202004902] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Indexed: 01/13/2023]
Abstract
Iodine catalysis was developed for aliphatic fluorination through light-promoted homolytic C-H bond cleavage. The intermediary formation of amidyl radicals enables selective C-H functionalization via carbon-centered radicals. For the subsequent C-F bond formation, previous methods have typically been limited by a requirement for electrophilic fluorine reagents. We here demonstrate that the intermediary instalment of a carbon-iodine bond sets the stage for an umpolung, thereby establishing an unprecedented nucleophilic fluorination pathway.
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Affiliation(s)
- Daniel Bafaluy
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, Av. Països Catalans, 16, 43007, Tarragona, Spain
| | - Zoritsa Georgieva
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, Av. Països Catalans, 16, 43007, Tarragona, Spain
| | - Kilian Muñiz
- 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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27
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Kato T, Maruoka K. Design of Bowl‐Shaped
N
‐Hydroxyimide Derivatives as New Organoradical Catalysts for Site‐Selective C(sp
3
)−H Bond Functionalization Reactions. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Terumasa Kato
- School of Chemical Engineering and Light Industry Guangdong University of Technology Guangzhou 510006 China
| | - Keiji Maruoka
- School of Chemical Engineering and Light Industry Guangdong University of Technology Guangzhou 510006 China
- Department of Chemistry Graduate School of Science Kyoto University Sakyo Kyoto 606-8502 Japan
- Graduate School of Pharmaceutical Sciences Kyoto University Sakyo Kyoto 606-8501 Japan
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28
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Buss JA, Vasilopoulos A, Golden DL, Stahl SS. Copper-Catalyzed Functionalization of Benzylic C-H Bonds with N-Fluorobenzenesulfonimide: Switch from C-N to C-F Bond Formation Promoted by a Redox Buffer and Brønsted Base. Org Lett 2020; 22:5749-5752. [PMID: 32790419 PMCID: PMC7446155 DOI: 10.1021/acs.orglett.0c02239] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A copper catalyst in combination with N-fluorobenzenesulfonimide (NFSI) has been reported to functionalize benzylic C-H bonds to the corresponding benzylic sulfonimides via C-N coupling. Here, we reported a closely related Cu-catalyzed method with NFSI that instead leads to C-F coupling. This switch in selectivity arises from changes to the reaction conditions (Cu/ligand ratio, temperature, addition of base) and further benefits from inclusion of MeB(OH)2 in the reaction. MeB(OH)2 is shown to serve as a "redox buffer" in the reaction, responsible for rescuing inactive Cu(II) for continued promotion of fluorination reactivity.
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Affiliation(s)
- Joshua A. Buss
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States
| | - Aristidis Vasilopoulos
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States
| | - Dung L. Golden
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States
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29
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Bafaluy D, Georgieva Z, Muñiz K. Iodine Catalysis for C(sp
3
)–H Fluorination with a Nucleophilic Fluorine Source. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daniel Bafaluy
- Institute of Chemical Research of Catalonia, ICIQ The Barcelona Institute of Science and Technology Av. Països Catalans, 16 43007 Tarragona Spain
| | - Zoritsa Georgieva
- Institute of Chemical Research of Catalonia, ICIQ The Barcelona Institute of Science and Technology Av. Països Catalans, 16 43007 Tarragona Spain
| | - Kilian Muñiz
- 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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30
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Kato T, Maruoka K. Design of Bowl‐Shaped
N
‐Hydroxyimide Derivatives as New Organoradical Catalysts for Site‐Selective C(sp
3
)−H Bond Functionalization Reactions. Angew Chem Int Ed Engl 2020; 59:14261-14264. [DOI: 10.1002/anie.202003982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/26/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Terumasa Kato
- School of Chemical Engineering and Light Industry Guangdong University of Technology Guangzhou 510006 China
| | - Keiji Maruoka
- School of Chemical Engineering and Light Industry Guangdong University of Technology Guangzhou 510006 China
- Department of Chemistry Graduate School of Science Kyoto University Sakyo Kyoto 606-8502 Japan
- Graduate School of Pharmaceutical Sciences Kyoto University Sakyo Kyoto 606-8501 Japan
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31
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Artault M, Mokhtari N, Cantin T, Martin-Mingot A, Thibaudeau S. Superelectrophilic Csp 3-H bond fluorination of aliphatic amines in superacid: the striking role of ammonium-carbenium dications. Chem Commun (Camb) 2020; 56:5905-5908. [PMID: 32342071 DOI: 10.1039/d0cc02081h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The superacid-promoted electrophilic Csp3-H bond activation of aliphatic amines generates superelectrophilic species that can be subsequently fluorinated. Demonstrated by low-temperature in situ NMR experiments, the ammonium-carbenium dications, crucial for this reaction, can also react with C-H bonds opening future synthesis perspectives for this mode of activation.
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Affiliation(s)
- M Artault
- Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
| | - N Mokhtari
- Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
| | - T Cantin
- Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
| | - A Martin-Mingot
- Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
| | - S Thibaudeau
- Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
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32
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Yoshii T, Tsuzuki S, Sakurai S, Sakamoto R, Jiang J, Hatanaka M, Matsumoto A, Maruoka K. N-Hydroxybenzimidazole as a structurally modifiable platform for N-oxyl radicals for direct C-H functionalization reactions. Chem Sci 2020; 11:5772-5778. [PMID: 32832053 PMCID: PMC7416693 DOI: 10.1039/d0sc02134b] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/16/2020] [Indexed: 11/21/2022] Open
Abstract
A novel class of N-oxy radicals based on flexibly modifiable N-hydroxybenzimidazole skeleton was designed and applied to C–H functionalization reactions.
Methods for direct functionalization of C–H bonds mediated by N-oxyl radicals constitute a powerful tool in modern organic synthesis. While several N-oxyl radicals have been developed to date, the lack of structural diversity for these species has hampered further progress in this field. Here we designed a novel class of N-oxyl radicals based on N-hydroxybenzimidazole, and applied them to the direct C–H functionalization reactions. The flexibly modifiable features of these structures enabled facile tuning of their catalytic performance. Moreover, with these organoradicals, we have developed a metal-free approach for the synthesis of acyl fluorides via direct C–H fluorination of aldehydes under mild conditions.
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Affiliation(s)
- Tomomi Yoshii
- Department of Chemistry , Graduate School of Science , Kyoto University , Sakyo , Kyoto 606-8502 , Japan .
| | - Saori Tsuzuki
- Department of Chemistry , Graduate School of Science , Kyoto University , Sakyo , Kyoto 606-8502 , Japan .
| | - Shunya Sakurai
- Department of Chemistry , Graduate School of Science , Kyoto University , Sakyo , Kyoto 606-8502 , Japan .
| | - Ryu Sakamoto
- Department of Chemistry , Graduate School of Science , Kyoto University , Sakyo , Kyoto 606-8502 , Japan .
| | - Julong Jiang
- Institute for Research Initiatives , Division for Research Strategy , Graduate School of Materials Science , Data Science Center , Nara Institute of Science and Technology , Ikoma , Nara 630-0192 , Japan
| | - Miho Hatanaka
- Institute for Research Initiatives , Division for Research Strategy , Graduate School of Materials Science , Data Science Center , Nara Institute of Science and Technology , Ikoma , Nara 630-0192 , Japan.,PRESTO , Japan Science and Technology (JST) , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan
| | - Akira Matsumoto
- Graduate School of Pharmaceutical Sciences , Kyoto University , Sakyo , Kyoto 606-8501 , Japan
| | - Keiji Maruoka
- Department of Chemistry , Graduate School of Science , Kyoto University , Sakyo , Kyoto 606-8502 , Japan . .,Graduate School of Pharmaceutical Sciences , Kyoto University , Sakyo , Kyoto 606-8501 , Japan.,School of Chemical Engineering and Light Industry , Guangdong University of Technology , Guangzhou 510006 , China
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33
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Bower JK, Cypcar AD, Henriquez B, Stieber SCE, Zhang S. C(sp 3)-H Fluorination with a Copper(II)/(III) Redox Couple. J Am Chem Soc 2020; 142:8514-8521. [PMID: 32275410 DOI: 10.1021/jacs.0c02583] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the growing interest in the synthesis of fluorinated organic compounds, few reactions are able to incorporate fluoride ions directly into alkyl C-H bonds. Here, we report the C(sp3)-H fluorination reactivity of a formally copper(III) fluoride complex. The C-H fluorination intermediate, LCuF, along with its chloride and bromide analogues, LCuCl and LCuBr, were prepared directly from halide sources with a chemical oxidant and fully characterized with single-crystal X-ray diffraction, X-ray absorption spectroscopy, UV-vis spectroscopy, and 1H nuclear magnetic resonance spectroscopy. Quantum chemical calculations reveal significant halide radical character for all complexes, suggesting their ability to initiate and terminate a C(sp3)-H halogenation sequence by sequential hydrogen atom abstraction (HAA) and radical capture. The capability of HAA by the formally copper(III) halide complexes was explored with 9,10-dihydroanthracene, revealing that LCuF exhibits rates 2 orders of magnitude higher than LCuCl and LCuBr. In contrast, all three complexes efficiently capture carbon radicals to afford C(sp3)-halogen bonds. Mechanistic investigation of radical capture with a triphenylmethyl radical revealed that LCuF proceeds through a concerted mechanism, while LCuCl and LCuBr follow a stepwise electron transfer-halide transfer pathway. The capability of LCuF to perform both hydrogen atom abstraction and radical capture was leveraged to enable fluorination of allylic and benzylic C-H bonds and α-C-H bonds of ethers at room temperature.
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Affiliation(s)
- Jamey K Bower
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Andrew D Cypcar
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Brenda Henriquez
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, 3801 West Temple Avenue, Pomona, California 91768, United States
| | - S Chantal E Stieber
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, 3801 West Temple Avenue, Pomona, California 91768, United States
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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34
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Plummer CM, Li L, Chen Y. The post-modification of polyolefins with emerging synthetic methods. Polym Chem 2020. [DOI: 10.1039/d0py01279c] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This Perspective highlights the present state of polyolefin post-modification research, especially concerning recently developed C–H functionalization chemistry. Remaining challenges and emerging strategies within the field have also been discussed.
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Affiliation(s)
- Christopher M. Plummer
- School of Materials Science and Engineering
- Sun Yat-sen University
- Guangzhou 510275
- China
- Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education
| | - Le Li
- Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education
- Sun Yat-sen University
- Guangzhou 510275
- China
- School of Chemistry
| | - Yongming Chen
- School of Materials Science and Engineering
- Sun Yat-sen University
- Guangzhou 510275
- China
- Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education
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35
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Spencer ARA, Grainger R, Panigrahi A, Lepper TJ, Bentkowska K, Larrosa I. Transition metal-free cross-dehydrogenative arylation of unactivated benzylic C–H bonds. Chem Commun (Camb) 2020; 56:14479-14482. [DOI: 10.1039/d0cc06212j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cross-dehydrogenative arylation of benzylic C–H bonds with arenes provides straightforward access to synthetically useful 1,1-diarylmethanes, from readily available starting materials.
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Affiliation(s)
- Andrew R. A. Spencer
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Rachel Grainger
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Adyasha Panigrahi
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Thomas J. Lepper
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Katarzyna Bentkowska
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Igor Larrosa
- Department of Chemistry
- School of Natural Sciences
- University of Manchester
- Manchester M13 9PL
- UK
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36
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Pinter EN, Bingham JE, AbuSalim DI, Cook SP. N-Directed fluorination of unactivated Csp 3-H bonds. Chem Sci 2019; 11:1102-1106. [PMID: 34084366 PMCID: PMC8146735 DOI: 10.1039/c9sc04055b] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Site-selective fluorination of aliphatic C-H bonds remains synthetically challenging. While directed C-H fluorination represents the most promising approach, the limited work conducted to date has enabled just a few functional groups as the arbiters of direction. Leveraging insights gained from both computations and experimentation, we enabled the use of the ubiquitous amine functional group as a handle for the directed C-H fluorination of Csp3-H bonds. By converting primary amines to adamantoyl-based fluoroamides, site-selective C-H fluorination proceeds under the influence of a simple iron catalyst in 20 minutes. Computational studies revealed a unique reaction coordinate for the catalytic process and offer an explanation for the high site selectivity.
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Affiliation(s)
- Emily N Pinter
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington IN 47405-7102 USA
| | - Jenna E Bingham
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington IN 47405-7102 USA
| | - Deyaa I AbuSalim
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington IN 47405-7102 USA
| | - Silas P Cook
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington IN 47405-7102 USA
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37
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Kita Y, Shigetani S, Kamata K, Hara M. Benzylic C H fluorination over supported silver catalyst. MOLECULAR CATALYSIS 2019. [DOI: 10.1016/j.mcat.2019.110463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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38
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Szpera R, Moseley DFJ, Smith LB, Sterling AJ, Gouverneur V. Fluorierung von C‐H‐Bindungen: Entwicklungen und Perspektiven. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201814457] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Robert Szpera
- Chemistry Research Laboratory Oxford University 12 Mansfield Road Oxford OX1 3TA Großbritannien
| | - Daniel F. J. Moseley
- Chemistry Research Laboratory Oxford University 12 Mansfield Road Oxford OX1 3TA Großbritannien
| | - Lewis B. Smith
- Chemistry Research Laboratory Oxford University 12 Mansfield Road Oxford OX1 3TA Großbritannien
| | - Alistair J. Sterling
- Chemistry Research Laboratory Oxford University 12 Mansfield Road Oxford OX1 3TA Großbritannien
| | - Véronique Gouverneur
- Chemistry Research Laboratory Oxford University 12 Mansfield Road Oxford OX1 3TA Großbritannien
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39
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Szpera R, Moseley DFJ, Smith LB, Sterling AJ, Gouverneur V. The Fluorination of C-H Bonds: Developments and Perspectives. Angew Chem Int Ed Engl 2019; 58:14824-14848. [PMID: 30759327 DOI: 10.1002/anie.201814457] [Citation(s) in RCA: 235] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Indexed: 12/16/2022]
Abstract
This Review summarizes advances in fluorination by C(sp2 )-H and C(sp3 )-H activation. Transition-metal-catalyzed approaches championed by palladium have allowed the installation of a fluorine substituent at C(sp2 ) and C(sp3 ) sites, exploiting the reactivity of high-oxidation-state transition-metal fluoride complexes combined with the use of directing groups (some transient) to control site and stereoselectivity. The large majority of known methods employ electrophilic fluorination reagents, but methods combining a nucleophilic fluoride source with an oxidant have appeared. External ligands have proven to be effective for C(sp3 )-H fluorination directed by weakly coordinating auxiliaries, thereby enabling control over reactivity. Methods relying on the formation of radical intermediates are complementary to transition-metal-catalyzed processes as they allow for undirected C(sp3 )-H fluorination. To date, radical C-H fluorinations mainly employ electrophilic N-F fluorination reagents but a unique MnIII -catalyzed oxidative C-H fluorination using fluoride has been developed. Overall, the field of late-stage nucleophilic C-H fluorination has progressed much more slowly, a state of play explaining why C-H 18 F-fluorination is still in its infancy.
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Affiliation(s)
- Robert Szpera
- Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Daniel F J Moseley
- Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Lewis B Smith
- Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Alistair J Sterling
- Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Véronique Gouverneur
- Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford, OX1 3TA, UK
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40
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41
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Iwabuchi Y. Recent Progress in Oxidative Organic Transformations Employing Nitroxyl Radicals. J SYN ORG CHEM JPN 2019. [DOI: 10.5059/yukigoseikyokaishi.77.424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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42
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LaMartina KB, Kuck HK, Oglesbee LS, Al-Odaini A, Boaz NC. Selective benzylic C-H monooxygenation mediated by iodine oxides. Beilstein J Org Chem 2019; 15:602-609. [PMID: 30931001 PMCID: PMC6423598 DOI: 10.3762/bjoc.15.55] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/19/2019] [Indexed: 12/30/2022] Open
Abstract
A method for the selective monooxdiation of secondary benzylic C–H bonds is described using an N-oxyl catalyst and a hypervalent iodine species as a terminal oxidant. Combinations of ammonium iodate and catalytic N-hydroxyphthalimide (NHPI) were shown to be effective in the selective oxidation of n-butylbenzene directly to 1-phenylbutyl acetate in high yield (86%). This method shows moderate substrate tolerance in the oxygenation of substrates containing secondary benzylic C–H bonds, yielding the corresponding benzylic acetates in good to moderate yield. Tertiary benzylic C–H bonds were shown to be unreactive under similar conditions, despite the weaker C–H bond. A preliminary mechanistic analysis suggests that this NHPI-iodate system is functioning by a radical-based mechanism where iodine generated in situ captures formed benzylic radicals. The benzylic iodide intermediate then solvolyzes to yield the product ester.
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Affiliation(s)
- Kelsey B LaMartina
- Department of Chemistry and Physics, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA
| | - Haley K Kuck
- Department of Chemistry and Physics, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA
| | - Linda S Oglesbee
- Department of Chemistry and Physics, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA
| | - Asma Al-Odaini
- Department of Chemistry and Physics, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA
| | - Nicholas C Boaz
- Department of Chemistry and Physics, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA.,Department of Chemistry, Frick Chemical Laboratory, Princeton University, Washington Road, Princeton, NJ 08544 USA.,Permanent address: Department of Chemistry, North Central College, 30 N. Brainard Street, Naperville, IL 60540 USA; phone: +1-630-637-5187
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43
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Takahira Y, Chen M, Kawamata Y, Mykhailiuk P, Nakamura H, Peters BK, Reisberg SH, Li C, Chen L, Hoshikawa T, Shibuguchi T, Baran PS. Electrochemical C(sp 3)-H Fluorination. Synlett 2019; 30:1178-1182. [PMID: 33767531 DOI: 10.1055/s-0037-1611737] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A simple and robust method for electrochemical alkyl C-H fluorination is presented. Using a simple nitrate additive, a widely available fluorine source (Selectfluor), and carbon-based electrodes, a wide variety of activated and unactivated C-H bonds were converted to their C-F congeners. The scalability of the reaction was also demonstrated with a 100 gram preparation of fluorovaline.
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Affiliation(s)
- Yusuke Takahira
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Miao Chen
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yu Kawamata
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Pavel Mykhailiuk
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.,Enamine Ltd.; Chervonotkatska 78, 02094 Kyiv (Ukraine) and Taras Shevchenko National University of Kyiv; Chemistry Department; Volodymyrska 64, 01601 Kyiv (Ukraine)
| | - Hugh Nakamura
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Byron K Peters
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Solomon H Reisberg
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Chao Li
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Longrui Chen
- Asymchem Life Science (Tianjin), Tianjin Economic-Technological Development Zone, Tianjin 300457, China
| | - Tamaki Hoshikawa
- Discovery. Medicine Creation. Neurology Business Group, Eisai Co., Ltd. 5-1-3 Tokodai, Tsukuba-shi, Ibaraki, 300-2635, Japan
| | - Tomoyuki Shibuguchi
- Discovery. Medicine Creation. Neurology Business Group, Eisai Co., Ltd. 5-1-3 Tokodai, Tsukuba-shi, Ibaraki, 300-2635, Japan
| | - Phil S Baran
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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44
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Pirzer AS, Alvarez E, Friedrich H, Heinrich MR. Radical Carbofluorination of Alkenes with Arylhydrazines and Selectfluor: Additives, Mechanistic Pathways, and Polar Effects. Chemistry 2019; 25:2786-2792. [DOI: 10.1002/chem.201805256] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/23/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Anna S. Pirzer
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
| | - Eva‐Maria Alvarez
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
| | - Heike Friedrich
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
| | - Markus R. Heinrich
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
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45
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Jwad RS, Pang AHC, Hunter L, Read RW. In Pursuit of Fluorinated Sigma Receptor Ligand Candidates Related to [18F]-FPS. Aust J Chem 2019. [DOI: 10.1071/ch18510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This paper describes the synthesis of N-arylmethyl(1-benzyl) and N-aroyl(1-benzoyl) 4-(4-fluoromethylphenoxymethyl)piperidines as potential sigma receptor ligands analogous to the potent and highly selective sigma-1 ligand [18F]-FPS, but with enhanced or alternative binding and transport profiles. The synthesis involves N-aroylation of 4-hydroxmethylpiperidine or ethyl nipecotate, functional group manipulation of the ester group or simple activation of the hydroxyl group to introduce the phenoxy component, and subsequent functional group manipulation to reduce the amide group and introduce the fluorine into the fluoromethyl substituent. In its development, the synthesis was found to require early N-aroylation of the piperidine precursor to avoid complications due to anchimeric assistance by its nitrogen in subsequent displacement reactions. New evidence is presented on the pathway followed in a literature report of direct displacement of a benzylic hydroxyl group by fluoride ion under Appel-like conditions. Relevant to the literature report, the halide ion in the fluoromethylphenoxy 1-benzylpiperidine derivatives was surprisingly labile to hydrolytic displacement on chromatography and this aspect is worthy of further study. Moreover, the NMR spectra of the amides were complicated by geometric isomerism about the amide C(O)–N bond, but detailed analysis of spectra from 2-anisoyl derivatives allowed the assignment of diastereomeric contributors to consistent, secondary atropisomerism about the aryl–C(O) bond.
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46
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Meanwell M, Nodwell MB, Martin RE, Britton R. A Convenient Late-Stage Fluorination of Pyridylic C-H Bonds with N-Fluorobenzenesulfonimide. Angew Chem Int Ed Engl 2018; 55:13244-13248. [PMID: 27653634 DOI: 10.1002/anie.201606323] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/04/2016] [Indexed: 12/16/2022]
Abstract
Pyridine features prominently in pharmaceuticals and drug leads, and methods to selectively manipulate pyridine basicity or metabolic stability are highly sought after. A robust, metal-free direct fluorination of unactivated pyridylic C-H bonds was developed. This convenient reaction shows high functional-group tolerance and offers complimentary selectivity to existing C-H fluorination strategies. Importantly, this late-stage pyridylic C-H fluorination provides opportunities to rationally modulate the basicity, lipophilicity, and metabolic stability of alkylpyridine drugs.
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Affiliation(s)
- Michael Meanwell
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Matthew B Nodwell
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Rainer E Martin
- Medicinal Chemistry, Roche Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, CH-4070, Basel, Switzerland
| | - Robert Britton
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
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47
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Paeth M, Carson W, Luo JH, Tierney D, Cao Z, Cheng MJ, Liu W. Copper-Mediated Trifluoromethylation of Benzylic Csp 3 -H Bonds. Chemistry 2018; 24:11559-11563. [PMID: 29905985 DOI: 10.1002/chem.201802766] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Indexed: 12/18/2022]
Abstract
Trifluoromethyl-containing compounds play a significant role in medicinal chemistry, materials and fine chemistry. Although direct C-H trifluoromethylation has been achieved on Csp2 -H bonds, direct conversion of Csp3 -H bonds to Csp3 -CF3 remains challenging. We report herein an efficient protocol for the selective trifluoromethylation of benzylic C-H bonds. This process is mediated by a combination CuIII -CF3 species and persulfate salts. A wide range of methylarenes can be selectively trifluoromethylated at the benzylic positions. A combination of experimental and theoretical mechanistic studies suggests that the reaction involves a radical intermediate and a CuIII -CF3 species as the CF3 transfer reagent.
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Affiliation(s)
- Matthew Paeth
- Department of Chemistry and Biochemistry, Miami University, 651. E. High Street, Oxford, Ohio, 45056, USA
| | - William Carson
- Department of Chemistry and Biochemistry, Miami University, 651. E. High Street, Oxford, Ohio, 45056, USA
| | - Jheng-Hua Luo
- Department of Chemistry, National Cheng Kung University, 1 University Road, Tainan City, Taiwan
| | - David Tierney
- Department of Chemistry and Biochemistry, Miami University, 651. E. High Street, Oxford, Ohio, 45056, USA
| | - Zhi Cao
- Synfuels China, Beijing, 100195 and Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi, 030001, P. R. China
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, 1 University Road, Tainan City, Taiwan
| | - Wei Liu
- Department of Chemistry and Biochemistry, Miami University, 651. E. High Street, Oxford, Ohio, 45056, USA
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48
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Bentley KW, Dummit KA, Van Humbeck JF. A highly site-selective radical sp 3 C-H amination of azaheterocycles. Chem Sci 2018; 9:6440-6445. [PMID: 30310574 PMCID: PMC6115697 DOI: 10.1039/c8sc00590g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 06/20/2018] [Indexed: 12/14/2022] Open
Abstract
This report describes the development of a novel C-H amination strategy using both a Cu(ii) Lewis acid and an organic hydrogen atom transfer catalyst to activate benzylic C-H bonds adjacent to aromatic N-heterocycles. This simple methodology demonstrates very high selectivity towards azaheterocycles without using exogenous directing groups and affords excellent site selectivity in substrates with more than one reactive position. A wide range of heterocyclic structures not compatible with previously reported catalytic systems have proven to be amenable to this approach. Mechanistic investigations strongly support a radical-mediated H-atom abstraction, which explains the observed contrast to known closed-shell Lewis acid catalyzed processes.
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Affiliation(s)
- Keith W Bentley
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge MA 02139 , USA
| | - Krysta A Dummit
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge MA 02139 , USA
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49
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Bume DD, Harry SA, Lectka T, Pitts CR. Catalyzed and Promoted Aliphatic Fluorination. J Org Chem 2018; 83:8803-8814. [PMID: 29894188 DOI: 10.1021/acs.joc.8b00982] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the last six years, the direct functionalization of aliphatic C-H (and C-C) bonds through user-friendly, radical-based fluorination reactions has emerged as an exciting research area in fluorine chemistry. Considering the historical narratives about the challenges of developing practical radical fluorination in organic frameworks, notable advancements in controlling both reactivity and selectivity have been achieved during this time. As one of the participants in the field, herein, we a provide brief account of research efforts in our laboratory from the initial discovery of radical monofluorination on unactivated C-H bonds in 2012 to more useful strategies to install fluorine on biologically relevant molecules through directed fluorination methods. In addition, accompanying mechanistic studies that have helped guide reaction design are highlighted in context.
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Affiliation(s)
| | | | | | - Cody Ross Pitts
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 2 , 8093 Zürich , Switzerland
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50
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Dempsey K, Mir R, Smajlagic I, Dudding T. Expanding the repertoire of cyclopropenium ion phase transfer catalysis: Benzylic fluorination. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.04.083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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