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.