Copper-promoted site-selective carbonylation of sp3 and sp2 C-H bonds with nitromethane.

Abstract

Copper-promoted direct carbonylation of unactivated sp3 C-H and aromatic sp2 C-H bonds of amides was developed using nitromethane as a novel carbonyl source. The sp3 C-H functionalization showed high site-selectivity by favoring the C-H bonds of α-methyl groups. The sp2 C-H carbonylation featured high regioselectivity and good functional group compatibility. Kinetic isotope effect studies indicated that the sp3 C-H bond breaking step is reversible, whereas the sp2 C-H bond cleavage is an irreversible but not the rate-determining step. Control experiments showed that a nitromethyl intermediate should be involved in the present reaction.