3,4-Annulated Indoles via Tandem Cyclopropane Ring-Opening/ Conia-ene and Michael Addition/Conia-ene Reactions

4-Alkynyl indoles, when treated with a benzylidene malonate or a donor-acceptor cyclopropane in the presence of a zinc halide, furnished 3,4-hexannylated or 3,4-heptannulated products, respectively, in fair to excellent yields. The reaction proceeds via a tandem addition/Conia-ene cyclization.

Automated summary

This article describes the study on the reaction of 4-alkynyl indoles with benzylidene malonate or donor-acceptor cyclopropane in the presence of a zinc halide. The reaction proceeds via a tandem addition/Conia-ene cyclization and provides fair to excellent yields of 3,4-hexannylated or 3,4-heptannulated products.