Visible-light-mediated direct C3 alkylation of quinoxalin-2(1H)-ones using alkanes

Abstract

Due to the high C–H bond dissociation energy of alkanes, the utilization of alkanes as alkyl radical precursors for C–H functionalization of heteroarenes is synthetically captivating but practically challenging, especially under metal- and photocatalyst-free conditions. We report herein a mild and practical visible-light-mediated method for C–H alkylation of quinoxalin-2(1H)-ones using trifluoroacetic acid as a hydrogen atom transfer reagent and air as an oxidant. This mild protocol was performed under metal- and photocatalyst-free circumstances and presented good functional-group tolerance as well as a broad substrate scope.