Intramolecular Cyclizations of Vinyl-Substituted N,N‑Dialkyl Arylamines Enabled by Borane-Assisted Hydride Transfer

Catalytic amounts of B­(C6F5)3 have been found to be able to promote the intramolecular cyclization of vinyl-substituted N,N-dialkyl arylamines to afford nitrogen-containing heterocycles. Our mechanistic studies indicate the reaction is initiated by abstraction of an α-hydride from an N-alkyl substi...

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Bibliographic Details
Published inACS catalysis Vol. 9; no. 1; pp. 295 - 300
Main Authors Tian, Jun-Jie, Zeng, Ning-Ning, Liu, Ning, Tu, Xian-Shuang, Wang, Xiao-Chen
Format Journal Article
LanguageEnglish
Published American Chemical Society 04.01.2019
Subjects
hydride abstraction
homogeneous catalysis
heterocycles
boron
cyclization
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Summary:Catalytic amounts of B­(C6F5)3 have been found to be able to promote the intramolecular cyclization of vinyl-substituted N,N-dialkyl arylamines to afford nitrogen-containing heterocycles. Our mechanistic studies indicate the reaction is initiated by abstraction of an α-hydride from an N-alkyl substituent by B­(C6F5)3, which is followed by cyclization, and is concluded by delivery of the hydride to the cyclic cationic intermediate. The dual roles of B­(C6F5)3, first as an oxidant and then as a hydride-carrying reductant, have enabled a rare redox-neutral cyclization process between a sp3 carbon and an electron-rich olefin without using a transition metal or an external oxidant.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.8b04485