Rhodium-Catalyzed Intermolecular Carbonylative [2+2+1] Cycloaddition of Alkynes Using Alcohol as the Carbon Monoxide Source for the Formation of Cyclopentenones

A highly regioselective rhodium-catalyzed intermolecular carbonylative [2 + 2 + 1] cycloaddition of alkynes using alcohol as a CO surrogate to access 4-methylene-2-cydopenten-l-ones has been developed. In this transformation, the alcohol performs multiple roles, including generating the Rh-H intermediate, functioning as the CO source, and assisting in the isomerization of the alkyne. Alkynes can act as both the olefin and the alkyne partner in the cyclopentenone core.