Rhenium and base co-catalyzed [3 + 2] annulations of N–H ketimines and alkynes to access unprotected tertiary indenamines through C–H bond activation

Abstract

Herein, a rhenium-catalyzed [3 + 2] carbocyclization of N–H ketimines and alkynes through C–H bond activation to afford unprotected tertiary indenamines is described. Notably, the catalytic use of a cheap base, sodium carbonate, was demonstrated to be crucial to the success of this reaction. The protocol is also highlighted by a high atom-economy, a broad substrate scope, and excellent regioselectivity for unsymmetrical alkynes.