Intramolecular reductive ketone-alkynoate coupling reaction promoted by (η2-propene)titanium.

Intramolecular reductive coupling of cycloalkanones tethered to alkynoates in the presence of (η(2)-propene)titanium was successfully performed to provide hydroxy-esters in a diastereoselective manner. Subsequent lactonization afforded angularly fused unsaturated tricyclic lactones which represent relevant substructures of numerous bioactive compounds.