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)‐α,β‐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 rhodium‐acyl reagents generated under CO pressure and promises a wide field of interest.