Visible-light-mediated eosin Y catalyzed aerobic desulfurization of thioamides into amides

Abstract

A novel method for the metal-free efficient synthesis of amides from thioamides using visible light and in an air atmosphere in the presence of eosin Y as an organophotoredox catalyst is reported. The protocol involves aerobic desulfurization–oxygenation of thioamides into amides in good to excellent yields at r.t. in a one-pot operation under mild conditions with the formation of nontoxic elemental sulfur as the only by-product. On the basis of several relevant experiments performed, it has been shown that the present photooxidation does not involve a singlet oxygen and accordingly a plausible organocatalytic photoredox mechanism is proposed.