Synthesis of alpha,beta-Unsaturated Ketones by Rhodium-Catalyzed Carbonylative Arylation of Internal Alkynes with Arylboronic Acids

The Rh-catalyzed reaction of arylboronic acids with internal alkynes under a CO atmosphere in the presence of an acid additive afforded alpha,beta-unsaturated ketones as the major products. Hydroacylation of internal alkynes, except in the case of diaryl acetylenes, proceeded in syn fashion, yielding the E-configured isomer. A mixture of E- and Z-isomers was obtained with diphenyl acetylene. Reactions were also highly regioselective for various nonsymmetric alkynes.