Transition-metal-free, visible-light-mediated cyclization of o-azidoarylalkynes with aryl diazonium salts

Abstract

Visible light along with 3 mol% eosin Y catalyzes the cyclization reaction of o-azidoarylalkynes with aryl diazonium salts by a photoredox process. We have investigated the scope of the reaction for several aryl diazonium salts and o-azidoarylalkynes. The general and easy procedure provides a transition-metal-free alternative for the formation of unsymmetrical 2,3-diaryl-substitued indoles.