Palladium-Catalyzed Asymmetric (3 + 2) Cycloaddition of Vinyl Epoxides with Substituted Propiolates. Enantioselective Formation of 2,3,4-Trisubstituted 2,3-Dihydrofurans.

Alkynyl esters are viable dipolarophiles for the palladium-catalyzed asymmetric (3 + 2) cycloaddition with vinyl epoxides. The chiral dihydrofurans are obtained in high yields and high ee values. The use of a chiral benzylic substituted P,N-ligand is essential. The usefulness of the synthetic method has been demonstrated; 2,3-cis-tetrahydrofuran was also provided.