Copper-Catalyzed Carbamoylation of Terminal Alkynes with Formamides via Cross-Dehydrogenative Coupling

An efficient approach for direct carbamoylation of terminal alkynes with formamides affording propiolamides has been developed by copper-catalyzed oxidative cross coupling of C­(sp)-H and C­(sp2)-H bonds in the presence of a pincer ligand with two imidazolyl groups. The catalytic reaction is compatible with diverse functional groups but sensitive to the electronic effect of terminal alkyne and the steric effect of formamides. KIE study indicates the cleavage of the carbamoyl C–H bond affording formamide radical is the rate-determining step.