Rhodium-Catalyzed Cross-Coupling Reactions of Carboxylate and Organoboron Compounds via Chelation-Assisted C–C Bond Activation

A new rhodium-catalyzed decarbonylated coupling reaction of ethyl benzo[h]quinoline-10-carboxylate and organoboron compounds that occurs through chelation-assisted sp2 C–COOEt bond activation was described. In this system CuCl played a very important role, and a five-membered rhodacycle was also involved as a key intermediate. Various functionalities were compatible in the reaction, and the desired products were obtained in good to excellent yields. DFT calculations on the mechanisms of this reaction using a Rh(I) model catalyst have also been carried out.