One-Pot Multicatalytic Approaches for the Synthesis of Cyclohepta[b]indoles, Indolotropones, and Tetrahydrocarbazoles.

Diversity oriented one-pot synthesis of cyclohepta[b]indoles, indolotropones, and tetrahydrocarbazoles (THCs) have been reported. Readily accessible 3-(2-aminophenyl)-5-hexenyn-3-ols under a one-pot trimetallic orthogonal catalysis furnish tetrahydrocyclohepta[b]indoles, and a one-pot quadruple reaction sequence of the enynols generates dihydrocyclohepta[b]indoles and indolotropones. During this study, formation of THCs was realized to be a reason for the yield loss in certain cases, this observation led to the development of a one-pot bimetallic approach for the synthesis of 1,3-disubstituted THCs.