Brønsted acid catalyzed multicomponent synthesis of N-arylindole and N-arylbenzo[e]indole
Muhammad Kamran Farooqi1, Shou-Jin Xiao2, Zhen Liu2
1Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 430074, Wuhan, China. liminghaochem@hust.edu.cn.
Abstract:
The indole skeleton was efficiently constructed via a practical acid-catalyzed multicomponent reaction (MCR) using readily accessible anilines, 4-hydroxycyclohexanone or 2-tetralone, and 2,2-dimethoxyacetaldehyde. This transformation proceeds through a cascade pathway involving aldol condensation, deprotonative aromatization and intramolecular cyclization. As a facile acid-mediated annulative MCR protocol, this method enables the convenient synthesis of C2,C3-unsubstituted indoles under mild and environmentally benign reaction conditions. The scope of the reactions was scouted and more than 40 derivatives were described.
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