Visible-light-initiated photo-oxidative cyclization of phenolic amidines using CBr4 – A metal free approach to 2-aminobenzoxazoles

Abstract

A mild and efficient one-pot operation for the amination of benzoxazoles has been achieved via ring opening of benzoxazoles followed by visible-light-mediated aerobic photo-oxidative cyclization of the resulting o-phenolic amidines using CBr₄ as a mild oxidant. The protocol is economical and environmentally benign as it utilizes visible light and does not require any photosensitizers, additives, heating or inert conditions.