Carbonylative addition of arylboronic acids to terminal alkynes:: A new catalytic access to α,β-unsaturated ketones

The carbonylative addition of arylboronic acids to terminal alkynes under mild conditions affords (E)-alpha,beta-unsaturated ketones with good yields. The reaction was achieved with chloro (1,5-cyclooctadiene)rhodium(I) dimer or chlorodicarbonylrhodium(I) dimer as catalytic precursor without additional phosphine as their use inhibits the reaction. Experiments using deuterated 1-hexyne discarded the possibility of a rhodium-vinylidene intermediate, thus a catalytic cycle involving a 1,2-insertion of the terminal alkyne in a rhodium-acyl bond is proposed. This new reaction represents the first example of the hydroacylation of terminal alkynes involving rhodiumacyl reagents generated under CO pressure and promises a wide field of interest.