Cobalt-Catalyzed Reductive Carboxylation of Aryl Bromides with Carbon Dioxide

Cobalt-catalyzed reductive carboxylation of aryl bromides with carbon dioxide has been developed. The reaction proceeded under one atm pressure of CO 2 at 40 °C in the presence of cobalt iodide/2,2′-bipyridine catalysts and zinc dust as a reducing reagent. Various aryl bromides could be converted to the corresponding carboxylic acids in good to high yields. Preliminary mechanistic experiments ruled out intervention of intermediate organozinc species for carboxylation with CO 2 , thus suggesting a direct CO 2 insertion into the corresponding ArCoBr species.