Copper-catalyzed intermolecular C(sp3)-H bond functionalization towards the synthesis of tertiary carbamates

We describe the development of an intermolecular unactivated C(sp(3))-H bond functionalization towards the direct synthesis of tertiary carbamates. The transformation proceeded using a readily available, abundant first-row transition metal catalyst (copper), and isocyanates as the source of the amide moiety. This is a novel strategy for direct transformation of a variety of unactivated hydrocarbon feedstocks to N-alkyl-N-aryl and N, N-dialkyl carbamates without pre-functionalization or installation of a directing group. The reaction had a broad substrate scope with 3 degrees > 2 degrees > 1 degrees site selectivity. The reaction proceeded even on a gram scale, and a corresponding free amine was directly obtained when the reaction was performed at high temperature. Kinetic studies suggested that radical-mediated C(sp(3))-H bond cleavage was the rate-determining step.