1
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Jiao Z, Jaunich KT, Tao T, Gottschall O, Hughes MM, Turlik A, Schuppe AW. Unified Approach to Deamination and Deoxygenation Through Isonitrile Hydrodecyanation: A Combined Experimental and Computational Investigation. Angew Chem Int Ed Engl 2024; 63:e202405779. [PMID: 38619535 DOI: 10.1002/anie.202405779] [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: 03/25/2024] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 04/16/2024]
Abstract
Herein, we describe a general hydrodefunctionalization protocol of alcohols and amines through a common isonitrile intermediate. To cleave the relatively inert C-NC bond, we leveraged dual hydrogen atom transfer (HAT) and photoredox catalysis to generate a nucleophilic boryl radical, which readily forms an imidoyl radical intermediate from the isonitrile. Rapid β-scission then accomplishes defunctionalization. This method has been applied to the hydrodefunctionalization of both amine and alcohol-containing pharmaceuticals, natural products, and biomolecules. We extended this approach to the reduction of carbonyls and olefins to their saturated counterparts, as well as the hydrodecyanation of alkyl nitriles. Both experimental and computational studies demonstrate a facile β-scission of the imidoyl radical, and reconcile differences in reactivity between nitriles and isonitriles within our protocol.
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Affiliation(s)
- Ziqi Jiao
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Kyle T Jaunich
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Thomas Tao
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Olivia Gottschall
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Maxwell M Hughes
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Aneta Turlik
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Alexander W Schuppe
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
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2
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Phang YL, Jin JK, Zhang FL, Wang YF. Radical hydroboration for the synthesis of organoboron compounds. Chem Commun (Camb) 2024; 60:4275-4289. [PMID: 38566567 DOI: 10.1039/d4cc00398e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Organoboron compounds demonstrate diverse applications in the fields of organic synthesis, materials science, and medicinal chemistry. Compared to the conventional hydroboration reaction, radical hydroboration serves as an alternative approach for the synthesis of organoborons via different mechanisms. In radical hydroboration, a boryl radical is initially generated from homolytic cleavage of a B-H or a B-B bond, which is then added to an unsaturated double bond to deliver a carbon radical. Subsequent hydrogen atom transfer or reduction of the carbon radical to form a carbanion followed by protonation gave the final product. Over the past few years, numerous efforts have been made for efficient synthesis of boryl radicals and the expansion of substrate scope of the radical hydroboration reaction. Here, we discuss the recent advancement of radical hydroboration and its associated mechanisms. Numerous radical hydroboration strategies employing N-heterocyclic carbene borane, bis(pinacolato)diboron and pinacolborane as the boron source were illustrated. Thermochemical, photochemical and electrochemical strategies for the generation of boryl radicals were also discussed in detail.
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Affiliation(s)
- Yee Lin Phang
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Ji-Kang Jin
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Feng-Lian Zhang
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Yi-Feng Wang
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
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3
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Xie Y, Zhang R, Chen Z, Rong M, He H, Ni S, He X, Xiao W, Xuan J. Photocatalytic Boryl Radicals Triggered Sequential B─N/C─N Bond Formation to Assemble Boron-Handled Pyrazoles. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306728. [PMID: 38018506 PMCID: PMC10797447 DOI: 10.1002/advs.202306728] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 10/26/2023] [Indexed: 11/30/2023]
Abstract
Vinyldiazo compounds are one of the most important synthons in the construction of a cyclic ring. Most photochemical transformations of vinyldiazo compounds are mainly focusing on utilization of their C═C bond site, while reactions taking place at terminal nitrogen atom are largely unexplored. Herein, a photocatalytic cascade radical cyclization of LBRs with vinyldiazo reagents through sequential B─N/C─N bond formation is described. The reaction starts with the addition of LBRs (Lewis base-boryl radicals) at diazo site, followed by intramolecular radical cyclization to access a wide range of important boron-handled pyrazoles in good to excellent yields. Control experiments, together with detailed mechanism studies well explain the observed reactivity. Further studies demonstrate the utility of this approach for applications in pharmaceutical and agrochemical research.
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Affiliation(s)
- Yang Xie
- Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials and Key Laboratory of Functional Inorganic Materials of Anhui ProvinceCollege of Chemistry & Chemical EngineeringAnhui UniversityHefeiAnhui230601P. R. China
| | - Ruilong Zhang
- Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials and Key Laboratory of Functional Inorganic Materials of Anhui ProvinceCollege of Chemistry & Chemical EngineeringAnhui UniversityHefeiAnhui230601P. R. China
| | - Ze‐Le Chen
- Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials and Key Laboratory of Functional Inorganic Materials of Anhui ProvinceCollege of Chemistry & Chemical EngineeringAnhui UniversityHefeiAnhui230601P. R. China
| | - Mengtao Rong
- Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials and Key Laboratory of Functional Inorganic Materials of Anhui ProvinceCollege of Chemistry & Chemical EngineeringAnhui UniversityHefeiAnhui230601P. R. China
| | - Hui He
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong ProvinceShantou UniversityShantouGuangdong515063P. R. China
| | - Shaofei Ni
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong ProvinceShantou UniversityShantouGuangdong515063P. R. China
| | - Xiang‐Kui He
- Key Laboratory of Pesticide and Chemical BiologyMinistry of EducationCollege of ChemistryCentral China Normal UniversityWuhanHubei430079P. R. China
| | - Wen‐Jing Xiao
- Key Laboratory of Pesticide and Chemical BiologyMinistry of EducationCollege of ChemistryCentral China Normal UniversityWuhanHubei430079P. R. China
| | - Jun Xuan
- Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials and Key Laboratory of Functional Inorganic Materials of Anhui ProvinceCollege of Chemistry & Chemical EngineeringAnhui UniversityHefeiAnhui230601P. R. China
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4
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Wang CL, Wang J, Jin JK, Li B, Phang YL, Zhang FL, Ye T, Xia HM, Hui LW, Su JH, Fu Y, Wang YF. Boryl radical catalysis enables asymmetric radical cycloisomerization reactions. Science 2023; 382:1056-1065. [PMID: 38033072 DOI: 10.1126/science.adg1322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 10/25/2023] [Indexed: 12/02/2023]
Abstract
The development of functionally distinct catalysts for enantioselective synthesis is a prominent yet challenging goal of synthetic chemistry. In this work, we report a family of chiral N-heterocyclic carbene (NHC)-ligated boryl radicals as catalysts that enable catalytic asymmetric radical cycloisomerization reactions. The radical catalysts can be generated from easily prepared NHC-borane complexes, and the broad availability of the chiral NHC component provides substantial benefits for stereochemical control. Mechanistic studies support a catalytic cycle comprising a sequence of boryl radical addition, hydrogen atom transfer, cyclization, and elimination of the boryl radical catalyst, wherein the chiral NHC subunit determines the enantioselectivity of the radical cyclization. This catalysis allows asymmetric construction of valuable chiral heterocyclic products from simple starting materials.
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Affiliation(s)
- Chang-Ling Wang
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jie Wang
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ji-Kang Jin
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bin Li
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yee Lin Phang
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Feng-Lian Zhang
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Tian Ye
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hui-Min Xia
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Li-Wen Hui
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ji-Hu Su
- Chinese Academy of Sciences Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Yao Fu
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yi-Feng Wang
- Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
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5
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Xie F, Mao Z, Curran DP, Liang H, Dai W. Facile Borylation of Alkenes, Alkynes, Imines, Arenes and Heteroarenes with N-Heterocyclic Carbene-Boranes and a Heterogeneous Semiconductor Photocatalyst. Angew Chem Int Ed Engl 2023; 62:e202306846. [PMID: 37555790 DOI: 10.1002/anie.202306846] [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: 05/16/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/10/2023]
Abstract
Although the development of radical chain and photocatalytic borylation reactions using N-heterocyclic carbene (NHC)-borane as boron source is remarkable, the persistent problems, including the use of hazardous and high-energy radical initiators or the recyclability and photostability issues of soluble homogeneous photocatalysts, still leave great room for further development in a sustainable manner. Herein, we report a conceptually different approach toward highly functionalized organoborane synthesis by using recoverable ultrathin cadmium sulfide (CdS) nanosheets as a heterogeneous photocatalyst, and a general and mild borylation platform that enables regioselective borylation of a wide variety of alkenes (arylethenes, trifluoromethylalkenes, α,β-unsaturated carbonyl compounds and nitriles), alkynes, imines and electron-poor aromatic rings with NHC-borane as boryl radical precursor. Mechanistic studies and density functional theory (DFT) calculations reveal that both photogenerated electrons and holes on the CdS fully perform their own roles, thereby resulting in enhancement of photocatalytic activity and stability of CdS.
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Affiliation(s)
- Fukai Xie
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Zhan Mao
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15208, USA
| | - Hongliang Liang
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Wen Dai
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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6
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Li FX, Wang X, Lin J, Lou X, Ouyang J, Hu G, Quan Y. Selective multifunctionalization of N-heterocyclic carbene boranes via the intermediacy of boron-centered radicals. Chem Sci 2023; 14:6341-6347. [PMID: 37325159 PMCID: PMC10266453 DOI: 10.1039/d3sc01132a] [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: 03/02/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023] Open
Abstract
The selective difunctionalization of N-heterocyclic carbene (NHC) boranes with alkenes has been achieved via decatungstate and thiol synergistic catalysis. The catalytic system also allows stepwise trifunctionalization, leading to complex NHC boranes with three different functional groups which are challenging to prepare by other methods. The strong hydrogen-abstracting ability of the excited decatungstate enables the generation of boryl radicals from mono- and di-substituted boranes for realizing borane multifunctionalization. This proof-of-principle research provides a new chance for fabricating unsymmetrical boranes and developing boron-atom-economic synthesis.
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Affiliation(s)
- Feng-Xing Li
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
| | - Xinmou Wang
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
| | - Jiaxin Lin
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
| | - Xiangyu Lou
- Department of Chemistry, The Chinese University of Hong Kong Shatin, N.T. Hong Kong SAR China
| | - Jing Ouyang
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
| | - Guanwen Hu
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
| | - Yangjian Quan
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong SAR China
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7
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Li X, Zhang G, Song Q. Recent advances in the construction of tetracoordinate boron compounds. Chem Commun (Camb) 2023; 59:3812-3820. [PMID: 36883254 DOI: 10.1039/d2cc06982b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Tetracoordinate boron compounds are a highly important class of molecules, which are the key intermediates in many organoboron-related chemical transformations and have unique luminescence properties. However, the synthesis of tetracoordinate boron compounds has never been reviewed. In this highlight, we summarize recent progress on the construction of racemic and chiral tetracoordinate borons, and hope to provide ideas for the assembly of them in more efficient ways, especially for the construction of boron-stereogenic compounds.
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Affiliation(s)
- Xue Li
- Institute of Next Generation Matter Transformation, College of Material Sciences Engineering at Huaqiao University, 668 Jimei Blvd, Xiamen, Fujian, 361021, China.
| | - Guan Zhang
- Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian, 350108, China
| | - Qiuling Song
- Institute of Next Generation Matter Transformation, College of Material Sciences Engineering at Huaqiao University, 668 Jimei Blvd, Xiamen, Fujian, 361021, China. .,Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian, 350108, China.,School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, China
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8
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Peng TY, Zhang FL, Wang YF. Lewis Base-Boryl Radicals Enabled Borylation Reactions and Selective Activation of Carbon-Heteroatom Bonds. Acc Chem Res 2023; 56:169-186. [PMID: 36571794 DOI: 10.1021/acs.accounts.2c00752] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
ConspectusThe past decades have witnessed tremendous progress on radical reactions. However, in comparison with carbon, nitrogen, oxygen, and other main group element centered radicals, the synthetic chemistry of boron centered radicals was less studied, mainly due to the high electron-deficiency and instability of such 3-center-5-electron species. In the 1980s, Roberts and co-workers found that the coordination of a Lewis base (amines or phosphines) with the boron center could form 4-center-7-electron boryl radicals (Lewis base-boryl radicals, LBRs) that are found to be more stable. However, only limited synthetic applications were developed. In 2008, Curran and co-workers achieved a breakthrough with the discovery of N-heterocyclic carbene (NHC) boryl radicals, which could enable a range of radical reduction and polymerization reactions. Despite these exciting findings, more powerful and valuable synthetic applications of LBRs would be expected, given that the structures and reactivities of LBRs could be easily modulated, which would provide ample opportunities to discover new reactions. In this Account, a summary of our key contributions in LBR-enabled radical borylation reactions and selective activation of inert carbon-heteroatom bonds will be presented.Organoboron compounds have shown versatile applications in chemical society, and their syntheses rely principally on ionic borylation reactions. The development of mechanistically different radical borylation reactions allows synthesizing products that are inaccessible by traditional methods. For this purpose, we progressively developed a series of NHC-boryl radical mediated chemo-, regio-, and stereoselective radical borylation reactions of alkenes and alkynes, by which a wide variety of structurally diverse organoboron molecules were successfully prepared. The synthetic utility of these borylated products was also demonstrated. Furthermore, we disclosed a photoredox protocol for oxidative generation of NHC-boryl radicals, which enabled useful defluoroborylation and arylboration reactions.Selective bond activation is an ideal way to convert simple starting materials to value-added products, while the cleavage of inert chemical bonds, in particular the chemoselectivity control when multiple identical bonds are present in similar chemical environments, remains a long-standing challenge. We envisaged that finely tuning the properties of LBRs might provide a new solution to address this challenge. Recently, we disclosed a 4-dimethylaminopyridine (DMAP)-boryl radical promoted sequential C-F bond functionalization of trifluoroacetic acid derivatives, in which the α-C-F bonds were selectively snipped via a spin-center shift mechanism. This strategy enables facile conversion of abundantly available trifluoroacetic acid to highly valuable mono- and difluorinated molecules. Encouraged by this finding, we further developed a boryl radical enabled three-step sequence to construct all-carbon quaternary centers from a range of trichloromethyl groups, where the three C-Cl bonds were selectively cleaved by the rational choice of suitable boryl radical precursors in each step. Furthermore, a boryl radical promoted dehydroxylative alkylation of α-hydroxy carboxylic acid derivatives was achieved, allowing for the efficient conversion of some biomass platform molecules to high value products.
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Affiliation(s)
- Tian-Yu Peng
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China
| | - Feng-Lian Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China
| | - Yi-Feng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, China
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Metal-Free One-Pot Multi-Functionalization of Unsaturated Compounds with Interelement Compounds by Radical Process. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020787. [PMID: 36677845 PMCID: PMC9861539 DOI: 10.3390/molecules28020787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/14/2023]
Abstract
In recent years, the importance of "environmentally friendly manufacturing" has been increasing toward the establishment of a resource-recycling society. In organic synthesis, as well, it is becoming increasingly important to develop new synthetic strategies with resource conservation and the recycling of elemental resources in mind, rather than just only synthesis. Many studies on the construction of frameworks of functional molecules using ionic reactions and transition-metal-catalyzed reactions have been reported, but most of them have focused on the formation of carbon-carbon bonds. However, it is essential to introduce appropriate functional groups at appropriate positions in molecules in order for the molecules to express their functions, and furthermore, the highly selective preparation of multiple functional groups is considered important for the creation of new functional molecules. In this review, we focus on radical reactions with high functional group selectivity and overview the recent progress in practical methods for the simultaneous introduction of multiple functional groups and propose future synthetic strategies that emphasize the recycling of elemental resources and environmental friendliness.
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10
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Sim K, ul Ansari T, Park Y, Jeong Y, Oh S, Min H, Jeon D, Kim H, Cho C. A Regio‐ and Diastereoselective Stille Coupling/Intramolecular Diels–Alder Cascade for the Generation of Fused Pyridines and Application in the Synthesis of (+)‐Lycopladine A and (−)‐Lycoposerramine R. Angew Chem Int Ed Engl 2022; 61:e202212016. [DOI: 10.1002/anie.202212016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Indexed: 11/05/2022]
Affiliation(s)
- Kyu‐Hyun Sim
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Thameem ul Ansari
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Yong‐Gyu Park
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Yeolib Jeong
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Sang‐Ha Oh
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Hye‐Won Min
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Da‐Yoon Jeon
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
| | - Hyunwoo Kim
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Cheon‐Gyu Cho
- Department of Chemistry Hanyang University 222 Wangsimni-ro, Seongdong-gu Seoul 04763 Korea
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11
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Shim KH, Ansari TU, Park YG, Jeong Y, Oh SH, Min HW, Jeon DY, Kim H, Cho CG. A Regio‐ and Diastereoselective Stille Coupling/IMDA Cascade for the Generation of Fused Pyridines and Application in the Synthesis of (+)‐Lycopladine A and (‐)‐Lycoposerramine R. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202212016] [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)
- Kyu-Hyun Shim
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Thameem ul Ansari
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Yong-Gyu Park
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Yeolib Jeong
- Korea Advanced Institute of Science and Technology Chemistry KOREA, REPUBLIC OF
| | - Sang-Ha Oh
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Hye-Won Min
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Da-Yoon Jeon
- Hanyang University - Seoul Campus: Hanyang University Chemistry KOREA, REPUBLIC OF
| | - Hyunwoo Kim
- Korea Advanced Institute of Science and Technology Chemistry KOREA, REPUBLIC OF
| | - Cheon-Gyu Cho
- Hanyang University - Seoul Campus: Hanyang University Chemistry 222 Wangsimni-roSeongdong-gu 04763 Seoul KOREA, REPUBLIC OF
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12
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Wu X, Chang Y, Lin S. Titanium Radical Redox Catalysis: Recent Innovations in Catalysts, Reactions, and Modes of Activation. Chem 2022; 8:1805-1821. [PMID: 36213842 PMCID: PMC9543366 DOI: 10.1016/j.chempr.2022.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radical chemistry has emerged as a cornerstone in modern organic synthesis, providing chemists with numerous new tools to rapidly expand reactivity and chemical space in academic and industrial research. In this regard, titanium complexes have been recognized as an attractive class of catalysts owing to their rich redox activities in addition to the abundance and low toxicity of this early transition metal. Traditionally employed for the activation of epoxides and carbonyl compounds, Ti radical redox catalysis has broken into new grounds in recent years, giving rise to a diverse repertoire of useful transformations. In this Perspective, we highlight recent developments in the area of TiIII/IV catalysis with respect to the activation of different types of chemical bonds. Furthermore, we discuss future opportunities in integrating Ti radical chemistry with other catalytic systems as well as with emerging new technologies such as photochemistry and electrochemistry.
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Affiliation(s)
- Xiangyu Wu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Yejin Chang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
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13
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Zhang Y, Liao Y, Liu P, Ran Y, Liu X. Radical borylation of vinyl azides with NHC-boranes: divergent synthesis of α-boryl ketones and borylated triazoles. Org Biomol Chem 2022; 20:3550-3557. [PMID: 35411904 DOI: 10.1039/d2ob00076h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A divergent radical borylation of vinyl azides with N-heterocyclic carbene (NHC) boranes in the presence of tBuSH is described. The protocol enables the divergent synthesis of α-boryl ketones and borylated triazoles with excellent functional group tolerance and a broad substrate scope. Remarkably, this work shows that vinyl azides can serve as unprecedented five-atom synthons for the construction of 1,2,3-triazoles without N2 extrusion.
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Affiliation(s)
- Yifei Zhang
- Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy, Zunyi Medical University, Zunyi 563000, China.
| | - Yangzhen Liao
- Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy, Zunyi Medical University, Zunyi 563000, China.
| | - Peijun Liu
- Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy, Zunyi Medical University, Zunyi 563000, China. .,Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi 563000, China
| | - Yu Ran
- Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy, Zunyi Medical University, Zunyi 563000, China.
| | - Xiaozu Liu
- Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy, Zunyi Medical University, Zunyi 563000, China. .,Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi 563000, China
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14
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Ma X, Kuang Z, Song Q. Recent Advances in the Construction of Fluorinated Organoboron Compounds. JACS AU 2022; 2:261-279. [PMID: 35252978 PMCID: PMC8889561 DOI: 10.1021/jacsau.1c00129] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Indexed: 05/05/2023]
Abstract
Fluorinated organoboron compounds are important synthetic building blocks that combine the unique characteristics of a fluorinated motif with the versatile synthetic applications of organoboron moiety. This review article guides the research on fluorinated organoboron compounds mainly from four aspects in recent years: selective monodefluoroborylation of polyfluoroarenes and polyfluoroalkenes, selective borylation of fluorinated substrates, selective fluorination of organoboron compounds, and borofluorination of alkynes/olefins. In addition, this review will provide a necessary guidance and inspiration for the research on the valuable synthetic building block fluorinated organoboron compounds.
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Affiliation(s)
- Xingxing Ma
- Key
Laboratory of Molecule Synthesis and Function Discovery, Fujian Province
University, College of Chemistry at Fuzhou
University, Fuzhou, Fujian 350108, China
| | - Zhijie Kuang
- Institute
of Next Generation Matter Transformation, College of Materials Science
Engineering & Chemical Engineering, Huaqiao University, 668 Jimei Boulevard, Xiamen, Fujian 361021, China
| | - Qiuling Song
- Key
Laboratory of Molecule Synthesis and Function Discovery, Fujian Province
University, College of Chemistry at Fuzhou
University, Fuzhou, Fujian 350108, China
- Institute
of Next Generation Matter Transformation, College of Materials Science
Engineering & Chemical Engineering, Huaqiao University, 668 Jimei Boulevard, Xiamen, Fujian 361021, China
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15
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Miao YQ, Pan QJ, Liu Z, Chen X. Visible-light-induced 1,2-diphenyldisulfane-catalyzed regioselective hydroboration of electron-deficient alkenes. NEW J CHEM 2022. [DOI: 10.1039/d2nj03930c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A photoinduced PhSSPh-catalyzed regioselective borylation of electron-deficient alkenes has been developed for the synthesis of borylated carbonyl, nitrile, sulfone, phosphonate, trifluoromethyl, and gem-diboron compounds.
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Affiliation(s)
- Yu-Qi Miao
- Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, China
| | - Qiao-Jing Pan
- Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, China
| | - Zhenxing Liu
- College of Chemistry, Zhengzhou University, Zhengzhou, Henan, China
| | - Xuenian Chen
- Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, China
- College of Chemistry, Zhengzhou University, Zhengzhou, Henan, China
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16
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Hsieh CE, Tsao CY, Chuang CH, Chen LW, Chou CM. Palladium-Catalyzed Regiospecific Decarboxylative Allylation of (Cyclohexadienylidene)malononitriles: Access to α-Allyl-α-aryl Malononitriles. J Org Chem 2021; 86:12168-12180. [PMID: 34346223 DOI: 10.1021/acs.joc.1c01503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A palladium-catalyzed regiospecific decarboxylative ε-allylation of (cyclohexadienylidene)malononitriles is presented for the synthesis of functionalized α-allyl-α-aryl malononitriles. This reaction proceeds via a resonance-stabilized α-aryl malononitrile anion, resulting in a wide range of α-allyl-α-aryl malononitriles in high yields with excellent linear product selectivity. We have also shown that the resulting products can be transformed into valuable synthetic intermediates by decyanation and Mizoroki-Heck arylation. In addition, an enantioselective decarboxylative allylation reaction is also presented.
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Affiliation(s)
- Cheng-En Hsieh
- Department of Applied Chemistry, National University of Kaohsiung, 700, Kaohsiung University Road, Nanzih District, 81148 Kaohsiung, Taiwan
| | - Chih-Yao Tsao
- Department of Applied Chemistry, National University of Kaohsiung, 700, Kaohsiung University Road, Nanzih District, 81148 Kaohsiung, Taiwan
| | - Cheng-Huan Chuang
- Department of Applied Chemistry, National University of Kaohsiung, 700, Kaohsiung University Road, Nanzih District, 81148 Kaohsiung, Taiwan
| | - Liang-Wei Chen
- Department of Applied Chemistry, National University of Kaohsiung, 700, Kaohsiung University Road, Nanzih District, 81148 Kaohsiung, Taiwan
| | - Chih-Ming Chou
- Department of Applied Chemistry, National University of Kaohsiung, 700, Kaohsiung University Road, Nanzih District, 81148 Kaohsiung, Taiwan
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17
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Abstract
Boron-centred radicals (boryl radicals) are potential and attractive species in main group chemistry and synthetic chemistry. Recently, the development of boron compounds ligated by N-heterocyclic carbenes (NHCs) has sparked off advavnces in boryl radical chemistry because NHCs can highly stabilise boryl radicals by electronic and steric factors. This review highlights recent synthesis and reactions of such NHC-boryl radicals. From the standpoint of main group chemistry, examples of isolation or detection of unique NHC-boryl radicals are presented. From the standpoint of synthetic chemistry, on the other hand, the development of reactions of user-friendly NHC-boryl radicals, which has contributed to radical chemistry, organoboron chemistry and polymer science, is comprehensively described.
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Affiliation(s)
- Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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18
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Abstract
Herein we report the first synthesis of borylfuroxans via the reaction of sulfonylfuroxans with Lewis base-ligated boranes under radical conditions. As a synthetic application, the transformation of borylfuroxans to a range of 1,2-dioximes and their derivatives is demonstrated.
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Affiliation(s)
- Weibin Xie
- Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501, Japan
| | - Masahiko Hayashi
- Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501, Japan
| | - Ryosuke Matsubara
- Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501, Japan
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19
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Liu Y, Li JL, Liu XG, Wu JQ, Huang ZS, Li Q, Wang H. Radical Borylative Cyclization of Isocyanoarenes with N-Heterocyclic Carbene Borane: Synthesis of Borylated Aza-arenes. Org Lett 2021; 23:1891-1897. [PMID: 33591193 DOI: 10.1021/acs.orglett.1c00309] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Borylated aza-arenes are of great importance in the area of organic synthesis. A radical borylative cyclization of isocyanoarenes with N-heterocyclic carbene borane (NHC-BH3) under metal-free conditions was developed. The reaction allows the efficient assembly of several types of borylated aza-arenes (phenanthridines, benzothiazoles, etc.), which are difficult to access using alternative methods. Mild reaction conditions, a good functional-group tolerance, and generally good efficiencies were observed. The utility of these products is demonstrated, and the mechanism is discussed.
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Affiliation(s)
- Yao Liu
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Ji-Lin Li
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xu-Ge Liu
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jia-Qiang Wu
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhi-Shu Huang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Qingjiang Li
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Honggen Wang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
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20
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Kawamoto T, Morioka T, Noguchi K, Curran DP, Kamimura A. Inverse Hydroboration of Imines with NHC-Boranes Is Promoted by Diphenyl Disulfide and Visible Light. Org Lett 2021; 23:1825-1828. [PMID: 33621108 DOI: 10.1021/acs.orglett.1c00230] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We describe a simple and efficient procedure for nucleophilic borylation of imines in the absence of a photoredox catalyst. Visible light irradiation of an acetonitrile solution of an imine, an NHC-borane, and diphenyl disulfide (10 mol %) provides various stable α-amino NHC-boranes in good yields. The reaction proceeds via addition of a nucleophilic boryl radical to an imine, followed by hydrogen abstraction from thiophenol, which is generated from NHC-borane and diphenyl disulfide.
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Affiliation(s)
- Takuji Kawamoto
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Tsubasa Morioka
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Kohki Noguchi
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Akio Kamimura
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
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21
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Patel RI, Sharma S, Sharma A. Cyanation: a photochemical approach and applications in organic synthesis. Org Chem Front 2021. [DOI: 10.1039/d1qo00162k] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review summarises the photocatalytic cyanation strategies to construct C(sp2)–CN, C(sp3)–CN and X–CN (X = N, S) bonds.
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Affiliation(s)
- Roshan I. Patel
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Shivani Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Anuj Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
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22
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Kundu G, Pahar S, Tothadi S, Sen SS. Stepwise Nucleophilic Substitution to Access Saturated N-heterocyclic Carbene Haloboranes with Boron–Methyl Bonds. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00691] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sanjukta Pahar
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Srinu Tothadi
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Sakya S. Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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23
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Han J, San HH, Guo A, Wang L, Tang X. Boryl Radical‐Mediated C−H Activation of Inactivated Alkanes for the Synthesis of Internal Alkynes. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000772] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jia‐Bin Han
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Htet Htet San
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
- Department of Industrial Chemistry Yadanabon University Amarapura Township Mandalay Region 05063 People's Republic of Myanmar
| | - Ao Guo
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Long Wang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Xiang‐Ying Tang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
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24
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Qu HJ, Yuan L, Jia CX, Yu HT, Xu H. DFT Investigation of Hydrogen Atom Abstraction from NHC-Boranes by Methyl, Ethyl and Cyanomethyl Radicals-Composition and Correlation Analysis of Kinetic Barriers. Molecules 2020; 25:molecules25194509. [PMID: 33019654 PMCID: PMC7582687 DOI: 10.3390/molecules25194509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/21/2020] [Accepted: 09/29/2020] [Indexed: 11/20/2022] Open
Abstract
Understanding the hydrogen atom abstraction (HAA) reactions of N-heterocyclic carbene (NHC)-boranes is essential for extending the practical applications of boron chemistry. In this study, density functional theory (DFT) computations were performed for the HAA reactions of a series of NHC-boranes attacked by •CH2CN, Me• and Et• radicals. Using the computed data, we investigated the correlations of the activation and free energy barriers with their components, including the intrinsic barrier, the thermal contribution of the thermodynamic reaction energy to the kinetic barriers, the activation Gibbs free energy correction and the activation zero-point vibrational energy correction. Furthermore, to describe the dependence of the activation and free energy barriers on the thermodynamic reaction energy or reaction Gibbs free energy, we used a three-variable linear model, which was demonstrated to be more precise than the two-variable Evans–Polanyi linear free energy model and more succinct than the three-variable Marcus-theory-based nonlinear HAA model. The present work provides not only a more thorough understanding of the compositions of the barriers to the HAA reactions of NHC-boranes and the HAA reactivities of the substrates but also fresh insights into the suitability of various models for describing the relationships between the kinetic and thermodynamic physical quantities.
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Affiliation(s)
- Hong-jie Qu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- College of Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Lang Yuan
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
| | - Cai-xin Jia
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
| | - Hai-tao Yu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- Correspondence: (H.-t.Y.); (H.X.); Tel.: +86-451-86608616 (H.-t.Y.)
| | - Hui Xu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- Correspondence: (H.-t.Y.); (H.X.); Tel.: +86-451-86608616 (H.-t.Y.)
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25
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Qu HJ, Yuan L, Jia CX, Yu HT, Xu H. DFT investigation of hydrogen atom-abstraction reactions of NHC-boranes by various carbon-centered radicals: barriers and correlation analyses. RSC Adv 2020; 10:34752-34763. [PMID: 35514392 PMCID: PMC9057721 DOI: 10.1039/d0ra07638d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 09/10/2020] [Indexed: 12/22/2022] Open
Abstract
In this study, we employed a quantum-mechanical computational method to investigate the hydrogen-atom abstraction reactions of two nitrogen heterocyclic carbene boranes (NHC-boranes), NHC-BH3 and NHC-BH2CN, by a series of carbon-centered radicals bearing various substituents. We explored the degree of correlation of the activation and free energy barriers to their components. Furthermore, we also investigated the effects of the radical and substituent sizes, nucleophilicity/electrophilicity indices, and the spin density distribution of the radical reactants on the three fundamental barriers and the thermal contribution of the reaction energy to the kinetic barrier. Using the generated data, we assessed the abilities of the various radical reactants to abstract the hydrogen atom from NHC-boranes. Further, we performed a similar analysis after dividing those radical reactants into four groups, which were classified based on the dominant factor affecting their electronic density distribution, which involves the inductive effect, conjugation, hyperconjugation, and the feedback of lone-pair electrons. The results and conclusions of this investigation not only provide insight into the relationships between some of the key kinetic and thermodynamic parameters, which is useful for understanding the dynamics of such hydrogen-abstraction reactions, but also provide information for selecting suitable radical reactants for further experimental investigations.
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Affiliation(s)
- Hong-Jie Qu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
- College of Science, Heilongjiang Bayi Agricultural University Daqing 163319 P. R. China
| | - Lang Yuan
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Cai-Xin Jia
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Hai-Tao Yu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Hui Xu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
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26
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Qi J, Zhang F, Jin J, Zhao Q, Li B, Liu L, Wang Y. New Radical Borylation Pathways for Organoboron Synthesis Enabled by Photoredox Catalysis. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915619] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Jing Qi
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Feng‐Lian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Ji‐Kang Jin
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Qiang Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Bin Li
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Lin‐Xuan Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
| | - Yi‐Feng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Hefei 230026 China
- Center for Excellence in Molecular Synthesis of CAS Hefei 230026 China
- State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China
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27
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Zhu C, Dong J, Liu X, Gao L, Zhao Y, Xie J, Li S, Zhu C. Photoredox‐Controlled β‐Regioselective Radical Hydroboration of Activated Alkenes with NHC‐Boranes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005749] [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)
- Congjun Zhu
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jie Dong
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Xueting Liu
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Liuzhou Gao
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jin Xie
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Shuhua Li
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Chengjian Zhu
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
- State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Shanghai 200032 China
- College of Chemistry and Molecular Engineering Zhengzhou University Zhengzhou 450001 China
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28
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Li L, Fang L, Wu W, Zhu J. Visible-Light-Mediated Intermolecular Radical Conjugate Addition for the Construction of Vicinal Quaternary Carbon Centers. Org Lett 2020; 22:5401-5406. [PMID: 32628495 DOI: 10.1021/acs.orglett.0c01724] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The visible light-driven organophotoredox catalysis is reported for the construction of vicinal quaternary carbon centers. Intermolecular conjugate addition of alkyl radicals, derived from 2,2-disubstituted dihydroquinazolinones, to Michael acceptors under blue light irradiation and rhodamine B catalysis allows the facile assembly of diverse, vicinal secondary/quaternary, tertiary/quaternary, and quaternary/quaternary carbon centers at room temperature. Our method provides a synthetically versatile protocol since both 2,2-disubstituted dihydroquinazolinones and Michael acceptors can be conveniently prepared from readily available ketones.
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Affiliation(s)
- Lei Li
- School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing 210023, China
| | - Lili Fang
- School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing 210023, China
| | - Weiping Wu
- School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing 210023, China
| | - Jin Zhu
- School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing 210023, China
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29
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Wang M, Shi Z. Methodologies and Strategies for Selective Borylation of C-Het and C-C Bonds. Chem Rev 2020; 120:7348-7398. [PMID: 32597639 DOI: 10.1021/acs.chemrev.9b00384] [Citation(s) in RCA: 177] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Organoborons have emerged as versatile building blocks in organic synthesis to achieve molecular diversity and as carboxylic acid bioisosteres with broad applicability in drug discovery. Traditionally, these compounds are prepared by the substitution of Grignard/lithium reagents with electrophilic boron species and Brown hydroboration. Recent developments have provided new routes for the efficient preparation of organoborons by applying reactions using chemical feedstocks with leaving groups. As compared to the previous methods that used organic halides (I, Br, and Cl), the direct borylation of less reactive C-Het and C-C bonds has become highly important to get efficiency and functional-group compatibility. This Review aims to provide a comprehensive overview of this topic, including (1) C-F bond borylation, (2) C-O bond borylation, (3) C-S bond borylation, (4) C-N bond borylation, and (5) C-C bond borylation. Considerable attention is given to the strategies and mechanisms involved. We expect that this Review will inspire chemists to discover more efficient transformations to expand this field.
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Affiliation(s)
- Minyan Wang
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Zhuangzhi Shi
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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30
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Qi J, Zhang FL, Jin JK, Zhao Q, Li B, Liu LX, Wang YF. New Radical Borylation Pathways for Organoboron Synthesis Enabled by Photoredox Catalysis. Angew Chem Int Ed Engl 2020; 59:12876-12884. [PMID: 32232933 DOI: 10.1002/anie.201915619] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/30/2020] [Indexed: 01/20/2023]
Abstract
Radical borylation using N-heterocyclic carbene (NHC)-BH3 complexes as boryl radical precursors has emerged as an important synthetic tool for organoboron assembly. However, the majority of reported methods are limited to reaction modes involving carbo- and/or hydroboration of specific alkenes and alkynes. Moreover, the generation of NHC-boryl radicals relies principally on hydrogen atom abstraction with the aid of radical initiators. A distinct radical generation method is reported, as well as the reaction pathways of NHC-boryl radicals enabled by photoredox catalysis. NHC-boryl radicals are generated via a single-electron oxidation and subsequently undergo cross-coupling with the in-situ-generated radical anions to yield gem-difluoroallylboronates. A photoredox-catalyzed radical arylboration reaction of alkenes was achieved using cyanoarenes as arylating components from which elaborated organoborons were accessed. Mechanistic studies verified the oxidative formation of NHC-boryl radicals through a single-electron-transfer pathway.
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Affiliation(s)
- Jing Qi
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Feng-Lian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Ji-Kang Jin
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Qiang Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Bin Li
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Lin-Xuan Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Yi-Feng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.,Center for Excellence in Molecular Synthesis of CAS, Hefei, 230026, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
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31
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Bolt DA, Curran DP. Reactions of NHC‐Boranes with Dibenzoyl Peroxide and Benzoic Acid. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000147] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Daniel A. Bolt
- Department of ChemistryUniversity of Pittsburgh Pittsburgh PA USA 15208
| | - Dennis P. Curran
- Department of ChemistryUniversity of Pittsburgh Pittsburgh PA USA 15208
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32
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Zhu C, Dong J, Liu X, Gao L, Zhao Y, Xie J, Li S, Zhu C. Photoredox‐Controlled β‐Regioselective Radical Hydroboration of Activated Alkenes with NHC‐Boranes. Angew Chem Int Ed Engl 2020; 59:12817-12821. [DOI: 10.1002/anie.202005749] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Congjun Zhu
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jie Dong
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Xueting Liu
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Liuzhou Gao
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jin Xie
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Shuhua Li
- Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Chengjian Zhu
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (ChemBIC) School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
- State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Shanghai 200032 China
- College of Chemistry and Molecular Engineering Zhengzhou University Zhengzhou 450001 China
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33
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Xia P, Song D, Ye Z, Hu Y, Xiao J, Xiang H, Chen X, Yang H. Photoinduced Single‐Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC–Borane. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201913398] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Peng‐Ju Xia
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Dan Song
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Zhi‐Peng Ye
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Yuan‐Zhuo Hu
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Jun‐An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and PhysicsNanning Normal University Nanning 530001 Guangxi P. R. China
| | - Hao‐Yue Xiang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Xiao‐Qing Chen
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
- Key Laboratory of Hunan Province for Water Environment and Agriculture Product SafetyCentral South University Changsha 410083 P. R. China
| | - Hua Yang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
- Key Laboratory of Hunan Province for Water Environment and Agriculture Product SafetyCentral South University Changsha 410083 P. R. China
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34
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Kawamoto T, Oritani K, Kawabata A, Morioka T, Matsubara H, Kamimura A. Hydrodecyanation of Secondary Alkyl Nitriles and Malononitriles to Alkanes using DiMeImd-BH 3. J Org Chem 2020; 85:6137-6142. [PMID: 32227846 DOI: 10.1021/acs.joc.0c00105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The decyanation of secondary aliphatic nitriles and the 2-fold decyanation of malononitriles leading to alkanes in the presence of 1,3-dimethylimidazol-2-ylidene borane (diMeImd-BH3) are reported. These reactions proceed via a radical mechanism that involves the addition of a borane radical to the nitrile to form an iminyl radical, followed by cleavage of a carbon-carbon bond. Theoretical calculations suggest that the β-cleavage of these iminyl radicals, which affords NHC-BH2CN and the corresponding alkyl radicals, is the rate-determining step in this reaction.
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Affiliation(s)
- Takuji Kawamoto
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Kyohei Oritani
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Atsushi Kawabata
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Tsubasa Morioka
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
| | - Hiroshi Matsubara
- Department of Chemistry, Graduate School of Sciences, Osaka Prefecture University, Sakai, Osaka, 599-8531, Japan
| | - Akio Kamimura
- Department of Applied Chemistry, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
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35
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Walton JC, Dai W, Curran DP. EPR Studies on the Addition of Ligated Boryl Radicals to Carbonyl Compounds. J Org Chem 2020; 85:4248-4255. [PMID: 32056434 DOI: 10.1021/acs.joc.9b03420] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The boron-centered radicals derived from alkenyl N-heterocyclic carbene (NHC)-boranes bearing ester substituents were recently found to ring close in 5-endo mode by addition to the oxygen atoms of the ester substituents. The inference from this was that NHC-boryl radicals might add intermolecularly to carbonyl-containing substrates. Several different NHC-boryl radicals were generated by H-atom abstraction from NHC-ligated trihydroborates. Electron paramagnetic resonance (EPR) spectroscopy proved that these did indeed add to the oxygen atoms of diaryl ketones with production of the corresponding bora-ketyl radicals. The same unusual regioselectivity of addition was observed with monoaryl ketones, but no bora-ketyls were observed with dialkyl ketones. Similarly, no bora-ketyl adduct radicals were observed with esters, even esters of benzoic acid. EPR spectroscopic evidence suggested that NHC-boryl radicals were also added to the O-atoms of aromatic aldehydes. Amine-boryl and phosphine-boryl radicals were also observed to add to the O-atom of benzophenone with production of the corresponding ketyl radicals.
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Affiliation(s)
- John C Walton
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
| | - Wen Dai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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36
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Xia PJ, Ye ZP, Hu YZ, Xiao JA, Chen K, Xiang HY, Chen XQ, Yang H. Photocatalytic C-F Bond Borylation of Polyfluoroarenes with NHC-boranes. Org Lett 2020; 22:1742-1747. [PMID: 32052975 DOI: 10.1021/acs.orglett.0c00020] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first photoredox-catalyzed defluoroborylation of polyfluoroarenes with NHC-BH3 has been facilely achieved at room temperature via a single-electron-transfer (SET)/radical addition pathway. This new strategy makes full use of the advantage of photoredox catalysis to generate the key boryl radical via direct activation of a B-H bond. Good functional group tolerance and high regioselectivity offer this protocol incomparable advantages in preparing a wide array of valuable polyfluoroarylboron compounds. Moreover, both computational and experimental studies were performed to illustrate the reaction mechanism.
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Affiliation(s)
- Peng-Ju Xia
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Zhi-Peng Ye
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Yuan-Zhuo Hu
- Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha 410083, P. R. China
| | - Jun-An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, P. R. China
| | - Kai Chen
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China.,State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, P. R. China
| | - Hao-Yue Xiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Xiao-Qing Chen
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China.,Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, P. R. China
| | - Hua Yang
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China.,Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, P. R. China
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37
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Xia PJ, Song D, Ye ZP, Hu YZ, Xiao JA, Xiang HY, Chen XQ, Yang H. Photoinduced Single-Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC-Borane. Angew Chem Int Ed Engl 2020; 59:6706-6710. [PMID: 31849140 DOI: 10.1002/anie.201913398] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 11/28/2019] [Indexed: 11/06/2022]
Abstract
A photoinduced SET process enables the direct B-H bond activation of NHC-boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC-boranes, thus obviating the need for extra radical initiators. The resulting NHC-boryl radical was used for the borylation of a wide range of α-trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway.
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Affiliation(s)
- Peng-Ju Xia
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Dan Song
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Zhi-Peng Ye
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Yuan-Zhuo Hu
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Jun-An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning, 530001, Guangxi, P. R. China
| | - Hao-Yue Xiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Xiao-Qing Chen
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
| | - Hua Yang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
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38
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Chen H, Sun S, Liu YA, Liao X. Nickel-Catalyzed Cyanation of Aryl Halides and Hydrocyanation of Alkynes via C–CN Bond Cleavage and Cyano Transfer. ACS Catal 2019. [DOI: 10.1021/acscatal.9b04586] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Hui Chen
- School of Pharmaceutical Sciences, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Shuhao Sun
- School of Pharmaceutical Sciences, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Yahu A. Liu
- Discovery Chemistry, Genomics Institute of the Novartis Research Foundation (GNF), San Diego, California 92121, United States
| | - Xuebin Liao
- School of Pharmaceutical Sciences, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
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39
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Weweler J, Younas SL, Streuff J. Titanium(III)-Catalyzed Reductive Decyanation of Geminal Dinitriles by a Non-Free-Radical Mechanism. Angew Chem Int Ed Engl 2019; 58:17700-17703. [PMID: 31513329 PMCID: PMC6899653 DOI: 10.1002/anie.201908372] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/19/2019] [Indexed: 01/14/2023]
Abstract
A titanium-catalyzed mono-decyanation of geminal dinitriles is reported. The reaction proceeds under mild conditions, tolerates numerous functional groups, and can be applied to quaternary malononitriles. A corresponding desulfonylation is demonstrated as well. Mechanistic experiments support a catalyst-controlled cleavage without the formation of free radicals, which is in sharp contrast to traditional stoichiometric radical decyanations. The involvement of two TiIII species in the C-C cleavage is proposed, and the beneficial role of added ZnCl2 and 2,4,6-collidine hydrochloride is investigated.
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Affiliation(s)
- Jens Weweler
- Institut für Organische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104Freiburg im BreisgauGermany
| | - Sara L. Younas
- Institut für Organische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104Freiburg im BreisgauGermany
| | - Jan Streuff
- Institut für Organische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104Freiburg im BreisgauGermany
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40
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Weweler J, Younas SL, Streuff J. Titan(III)‐katalysierte, reduktive Decyanierung geminaler Dinitrile ohne freie Radikalintermediate. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908372] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jens Weweler
- Institut für Organische ChemieAlbert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Deutschland
| | - Sara L. Younas
- Institut für Organische ChemieAlbert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Deutschland
| | - Jan Streuff
- Institut für Organische ChemieAlbert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Deutschland
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41
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Jin JK, Zheng WX, Xia HM, Zhang FL, Wang YF. Regioselective Radical Hydroboration of gem-Difluoroalkenes: Synthesis of α-Borylated Organofluorines. Org Lett 2019; 21:8414-8418. [PMID: 31596598 DOI: 10.1021/acs.orglett.9b03173] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A regioselective radical hydroboration of gem-difluoroalkenes was developed for the synthesis of α-difluoroalkylborons. The reaction features excellent regioselectivity, broad substrate scope, and good functional group capability. DFT calculations implicated the remarkable α-selectivity was driven from the kinetically and thermodynamically more favorable α-addition step. The resulting α-difluoroalkylborons could be readily converted into NHC-borane-tethered monofluoroalkenes, which demonstrated unique reactivity and applicability in the synthesis of monofluoroalkene derivatives through transformations of the boron unit.
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Affiliation(s)
- Ji-Kang Jin
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, and Department of Chemistry , University of Science and Technology of China , 96 Jinzhai Road , Hefei , Anhui 230026 , China
| | - Wan-Xin Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, and Department of Chemistry , University of Science and Technology of China , 96 Jinzhai Road , Hefei , Anhui 230026 , China
| | - Hui-Min Xia
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, and Department of Chemistry , University of Science and Technology of China , 96 Jinzhai Road , Hefei , Anhui 230026 , China
| | - Feng-Lian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, and Department of Chemistry , University of Science and Technology of China , 96 Jinzhai Road , Hefei , Anhui 230026 , China
| | - Yi-Feng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, and Department of Chemistry , University of Science and Technology of China , 96 Jinzhai Road , Hefei , Anhui 230026 , China.,State Key Laboratory of Elemento-Organic Chemistry , Nankai University , Tianjin 300071 , China
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42
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Affiliation(s)
- Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology; Kanazawa University; Kakuma-machi 920-1192 Kanazawa Japan
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43
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Aupic C, Abdou Mohamed A, Figliola C, Nava P, Tuccio B, Chouraqui G, Parrain JL, Chuzel O. Highly diastereoselective preparation of chiral NHC-boranes stereogenic at the boron atom. Chem Sci 2019; 10:6524-6530. [PMID: 31341605 PMCID: PMC6611065 DOI: 10.1039/c9sc01454c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 05/23/2019] [Indexed: 11/21/2022] Open
Abstract
Stereogenic main group elements are clearly generating interest in the enantioselective catalysis field. Surprisingly, while chiral organoboron reagents are very useful in stereoselective transformations, few scaffolds stereogenic at boron and configurationally stable have been reported to date. Herein, we describe an original library of chiral NHC-boranes, stereogenic at the boron atom, that has been prepared in only a few steps and in good yields (up to 93%). Key steps involve a chlorination/arylation sequence in the presence of simple Grignard reagents from bicyclic NHC-boranes. The high and unprecedented diastereoselectivity observed during the second step (up to 99 : 1 dr) has been rationalized through a plausible SRN1 mechanism thanks to EPR observations and DFT calculations.
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Affiliation(s)
- Clara Aupic
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | - Amel Abdou Mohamed
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | - Carlotta Figliola
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | - Paola Nava
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | | | - Gaëlle Chouraqui
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | - Jean-Luc Parrain
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
| | - Olivier Chuzel
- Aix Marseille Univ , CNRS , Centrale Marseille, iSm2 , Marseille , France .
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44
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Ren SC, Zhang FL, Xu AQ, Yang Y, Zheng M, Zhou X, Fu Y, Wang YF. Regioselective radical α-borylation of α,β-unsaturated carbonyl compounds for direct synthesis of α-borylcarbonyl molecules. Nat Commun 2019; 10:1934. [PMID: 31036844 PMCID: PMC6488649 DOI: 10.1038/s41467-019-09825-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 04/02/2019] [Indexed: 12/21/2022] Open
Abstract
Organoboron compounds are highly valuable in synthetic chemistry. In particular, α-borylcarbonyl compounds have shown versatile synthetic applications, owing to fruitful chemistries of both the boryl and carbonyl moieties. However, the synthesis of these molecules still remains tedious and time-consuming. Here we report a straightforward and practical route to synthesize α-borylcarbonyl molecules based on a regioselective radical α-borylation of α,β-unsaturated carbonyl compounds. The reaction features unusual α-regioselectivity and high functional-group compatibility. Further synthetic applications of new α-borylated products were also demonstrated. DFT and kinetic studies implicated that the α-regioselectivity of β-aryl-α,β-unsaturated carbonyl compounds was determined by the thermodynamically more favorable radical α-addition step, whereas the formation of α-addition products from β-alkyl-α,β-unsaturated carbonyl compounds was driven by an energetically favored hydrogen atom transfer step. Given that α,β-unsaturated carbonyl compounds can be easily obtained in abundance and variety, this method enjoys great advantages in diverse and economical synthesis of valuable α-borylcarbonyl molecules. α-Borylcarbonyl compounds are versatile synthons in organic synthesis, however their preparation is often tedious. Here, the authors report a regioselective radical α-borylation of α,β-unsaturated carbonyl compounds to afford α-borylcarbonyl molecules with high selectivity and functional group compatibility.
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Affiliation(s)
- Shi-Chao Ren
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Feng-Lian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Ai-Qing Xu
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Yinuo Yang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Min Zheng
- Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Xiaoguo Zhou
- Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.
| | - Yao Fu
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.
| | - Yi-Feng Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis of CAS, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China. .,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China.
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45
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Vallet AL, Lacôte E. Thiolation of NHC-boranes: influence of the substitution at boron. Org Biomol Chem 2019; 17:4234-4237. [PMID: 30951071 DOI: 10.1039/c9ob00578a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several N-Heterocyclic Carbene (NHC)-boryl sulfides with B-substituents were prepared. The added steric hindrance leads to much improved selectivities as only the NHC-boryl mono-sulfides were obtained. The B-substituted NHC-boranes are also conducive to more selective S to N NHC-boryl shift, provided that the NHC used is not too sterically demanding.
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Affiliation(s)
- Anne-Laure Vallet
- ICSN-CNRS, Bâtiment 27, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
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46
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Guo A, Han JB, Zhu L, Wei Y, Tang XY. Site-Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl Radicals. Org Lett 2019; 21:2927-2931. [PMID: 30924668 DOI: 10.1021/acs.orglett.9b00985] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel method for site-selective C-H functionalization of ethyl acetate mediated by pyridine-boryl radicals is presented, delivering a variety of 4-phenylbut-3-yn-2-yl acetate derivatives under mild conditions. A distinguishing feature of this reaction is that the pyridine-ligated boryl radicals can abstract the inactive α-hydrogen of the alkoxyl group instead of the α-hydrogen of carbonyl groups described in a previous report using amine-ligated boryl radicals. Significantly, substrates with halogen atoms are compatible under the reaction conditions.
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Affiliation(s)
- Ao Guo
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
| | - Jia-Bin Han
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
| | - Lei Zhu
- College of Chemistry and Materials Science , Hubei Engineering University , Hubei 432000 , People's Republic of China
| | - Yin Wei
- State Key Laboratory of Organometallic Chemistry , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , China
| | - Xiang-Ying Tang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
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47
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Shimoi M, Maeda K, Geib SJ, Curran DP, Taniguchi T. Esters as Radical Acceptors: β‐NHC‐Borylalkenyl Radicals Induce Lactonization by C−C Bond Formation/Cleavage on Esters. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Masaki Shimoi
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
| | - Katsuhiro Maeda
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
- Nano Life Science Institute (WPI-NanoLSI) Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
| | - Steven J. Geib
- Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA
| | - Dennis P. Curran
- Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA
| | - Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
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48
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Shimoi M, Maeda K, Geib SJ, Curran DP, Taniguchi T. Esters as Radical Acceptors: β‐NHC‐Borylalkenyl Radicals Induce Lactonization by C−C Bond Formation/Cleavage on Esters. Angew Chem Int Ed Engl 2019; 58:6357-6361. [DOI: 10.1002/anie.201902001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Masaki Shimoi
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
| | - Katsuhiro Maeda
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
- Nano Life Science Institute (WPI-NanoLSI) Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
| | - Steven J. Geib
- Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA
| | - Dennis P. Curran
- Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA
| | - Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology Kanazawa University, Kakuma-machi Kanazawa 920-1192 Japan
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49
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Dai W, Curran DP, Walton JC. EPR and Preparative Studies of 5- endo Cyclizations of Radicals Derived from Alkenyl NHC-Boranes Bearing tert-Butyl Ester Substituents. J Org Chem 2019; 84:2102-2111. [PMID: 30663305 DOI: 10.1021/acs.joc.8b03112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Radical H atom abstraction from a set of N-heterocyclic carbene (NHC) complexes of alkenylboranes bearing two tert-butyl ester substituents was studied by EPR spectroscopy. The initial boraallyl radical intermediates rapidly ring closed onto the O atoms of their distal ester groups in 5- endo mode to yield 1,2-oxaborole radicals. Unexpectedly, two structural varieties of these radicals were identified from their EPR spectra. These proved to be two stable rotamers, in which the carbonyl group of the tert-butyl ester was oriented toward and away from the NHC ring. These rotamers were akin to the s- trans and s- cis rotamers of α,β-unsaturated carbonyl compounds. Their stability was attributed to the quasi-allylic interaction of their unpaired electrons with the carbonyl units of their adjacent ester groups. EPR spectroscopic evidence for two rotamers of the analogous methyl ester containing NHC-oxaborole radicals was also obtained. An improved synthetic procedure for preparing rare NHC-boralactones was developed involving treatment of the alkenyl NHC-boranes with AIBN and tert-dodecanethiol.
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Affiliation(s)
- Wen Dai
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Dennis P Curran
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - John C Walton
- EaStCHEM School of Chemistry , University of St. Andrews , St. Andrews , Fife KY16 9ST , United Kingdom
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50
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Sivaguru P, Wang Z, Zanoni G, Bi X. Cleavage of carbon–carbon bonds by radical reactions. Chem Soc Rev 2019; 48:2615-2656. [DOI: 10.1039/c8cs00386f] [Citation(s) in RCA: 165] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This review provides insights into the in situ generated radicals triggered carbon–carbon bond cleavage reactions.
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Affiliation(s)
- Paramasivam Sivaguru
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis
- Northeast Normal University
- Changchun 130024
- China
| | - Zikun Wang
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis
- Northeast Normal University
- Changchun 130024
- China
| | | | - Xihe Bi
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis
- Northeast Normal University
- Changchun 130024
- China
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