Synthesis of Tetrahydro-5H-indolo[2,3-b]quinolines through Copper-Catalyzed Cascade Reactions of Aza-o-quinone Methides with Indoles

A variety of tetrahydro-5H-indolo[2,3-b]quinolines were prepared in 40-97% yields through a copper(II)-catalyzed cascade reaction of aza-o-quinone methides generated in situ from 2(chloromethyl)anilines and indoles. Experimental results showed that the reaction underwent double 1,4-additions and sequential intramolecular cyclization. The present method features broad substrate scope, good functional group tolerance, and easy gram scalable preparation of indolo[2,3-b]quinolines.

Automated summary

A variety of tetrahydro-5H-indolo[2,3-b]quinolines were efficiently synthesized through a copper(II)-catalyzed cascade reaction. This reaction involved double 1,4-additions and sequential intramolecular cyclization, and demonstrated broad substrate scope and scalability.