Borane-catalyzed cascade Friedel-Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization to afford
Bei-Bei Zhang1, Shuo Peng1, Feiyi Wang1
1Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, College of Chemistry and Chemical Engineering, Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University Wuhan 430062 P. R. China machao@hubu.edu.cn yangguichun@hubu.edu.cn.
Abstract:
An unprecedented redox-neutral annulation reaction of tertiary anilines with electron-deficient alkynes was developed that proceeds through a cascade Friedel-Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization sequence. Under B(C6F5)3 catalysis, a range of functionalized 1,2,3,4-tetrahydroquinolines were facilely constructed in moderate to good yields with exclusive 3,4-anti-stereochemistry. The commercial availability of the catalyst and the high atom and step economy of the procedure, together with metal-free and external oxidant-free conditions, make this an attractive method in organic synthesis.
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