Homogeneous cobalt catalyzed reductive formylation of N-heteroarenes with formic acid

Herein, we report a cobalt N,N-bidentate complex catalyzed reductive formylation of N-heteroarenes for the generation of N-formyltetrahydroquinoline (FTHQ) derivatives, formic acid was employed as a transfer hydrogenation reagent that was safe, abundant and easy to handle. This work represented the first homogeneous system for reductive formylation of N-heteroarenes, the metal ligand cooperated dehydrogenation was the key to the success of this transformation. Deuteration labelling experiments and Hammet analysis were conducted and a plausible mechanism was suggested.