Diastereoselectivity in the synthesis of bicyclic titanacyclopentenes from chiral 6-hepten-1-ynes

A variety of chiral 6-hepten-1-ynes have been found to undergo cyclization to titanabicyclopentenes by (eta(2)-propene)Ti(Oi-Pr)(2) with excellent yields and degrees of exo-stereoselectivity depending on the substrate steric requirements. In the framework of a plausible cyclization mechanism several conformational features which can regulate the stereoinduction have been suggested