Cobalt- and Nickel-Catalyzed Carboxylation of Alkenyl and Sterically Hindered Aryl Triflates Utilizing CO₂

A highly efficient cobalt-catalyzed reductive carboxylation reaction of alkenyl trifluoro­methane­sulfonates (triflates) has been developed. By employing Mn powder as a reducing reagent under 1 atm pressure of CO₂ at room temperature, diverse alkenyl triflates can be converted to the corresponding α,β-unsaturated carboxylic acids. Moreover, the carboxylation of sterically hindered aryl triflates proceeds smoothly in the presence of a nickel or cobalt catalyst