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-cyclopenten-1-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.