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Kiyokawa K, Noguchi I, Nagata T, Minakata S. Tris(pentafluorophenyl)borane-Catalyzed Stereospecific Bromocyanation of Styrene Derivatives with Cyanogen Bromide. Org Lett 2023; 25:2537-2542. [PMID: 36971409 DOI: 10.1021/acs.orglett.3c00727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
We, herein, report on the bromocyanation of styrene derivatives with cyanogen bromide in the presence of tris(pentafluorophenyl)borane which functions as a Lewis acid catalyst that can effectively activate cyanogen bromide. This reaction proceeds through a stereospecific syn-addition. The protocol is operationally simple and provides practical access to β-bromonitriles.
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Kiyokawa K, Ishizuka M, Minakata S. Stereospecific Oxycyanation of Alkenes with Sulfonyl Cyanide. Angew Chem Int Ed Engl 2023; 62:e202218743. [PMID: 36702752 DOI: 10.1002/anie.202218743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 01/28/2023]
Abstract
Oxycyanation of alkenes would allow the direct construction of useful β-hydroxy nitrile scaffolds. However, only limited examples of such reactions have been reported, and some problems including limited substrate scope and the lack of diastereocontrol in the case of the oxycyanation of internal alkenes have arisen. We herein report on the intermolecular oxycyanation of alkenes using p-toluenesulfonyl cyanide (TsCN) in the presence of tris(pentafluorophenyl)borane (B(C6 F5 )3 ) as a catalyst, affording products that contain a sulfinyloxy group and a cyano group at the vicinal position. The reaction features a stereospecific syn-addition. The reaction also shows a broad substrate scope with good functional group tolerance. Mechanistic investigations by experimental studies and density functional theory (DFT) calculations revealed that the reaction proceeds via an unprecedented stereospecific mechanism through the electrophilic cyanation of alkenes, in which B(C6 F5 )3 efficiently activates TsCN through the coordination of the cyano group to the boron center.
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Affiliation(s)
- Kensuke Kiyokawa
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
| | - Miu Ishizuka
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
| | - Satoshi Minakata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
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Yi ZJ, Sun JT, Yang TY, Yu XY, Han XL, Wei BG. Cu(OTf) 2-catalyzed C3 aza-Friedel-Crafts alkylation of indoles with N, O-acetals. Org Biomol Chem 2022; 20:2261-2270. [PMID: 35229848 DOI: 10.1039/d1ob02383g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
An efficient approach to access functionalized indole derivatives has been developed through Cu(OTf)2-catalyzed C3 aza-Friedel-Crafts alkylation of substituted indoles 5a-5m, N-methyl-pyrrole with linear N,O-acetals 4a-4l. As a result, a series of C3 amide aza-alkylated indole derivatives 6a-6ag and 7 were synthesized in moderate to excellent yields.
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Affiliation(s)
- Zi-Juan Yi
- Key Laboratory of Theoretical Organic Chemistry Functional Molecule, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, People's Republic of China. .,Department of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China.
| | - Jian-Ting Sun
- Department of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China.
| | - Tian-Yu Yang
- Department of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China.
| | - Xian-Yong Yu
- Key Laboratory of Theoretical Organic Chemistry Functional Molecule, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, People's Republic of China.
| | - Xiao-Li Han
- Department of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China. .,Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Bang-Guo Wei
- Department of Natural Medicine, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China.
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Abstract
In the last two decades, boron-based catalysis has been gaining increasing traction in the field of organic synthesis. The use of halogenated triarylboranes as main group Lewis acid catalysts is an attractive strategy. It has been applied in a growing number of transformations over the years, where they may perform comparably or even better than the gold standard catalysts. This review discusses methods of borane synthesis and cutting-edge boron-based Lewis acid catalysis, focusing especially on tris(pentafluorophenyl)-borane [B(C6F5)3], and other halogenated triarylboranes, highlighting how boron Lewis acids employed as catalysts can unlock a plethora of unprecedented chemical transformations or improve the efficiency of existing reactions.
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