Palladium/ N-Heterocyclic Carbene (NHC)-Catalyzed Asymmetric [3 + 2] Cycloaddition Reaction of Vinyl Epoxides with Allenic Amides.

Allenic amides are successfully developed as dipolarophiles to react with vinyl epoxides under Pd-catalysis. The chiral NHC showed its unique role as the ligand in this asymmetric [3 + 2] cycloaddition. Chiral tetrahydrofurans bearing three functional groups (monosubstituted alkene, tetrasubstituted enolether, and amide) and vicinal tertiary and quaternary stereocenters were obtained in high yields with high diastereo- and enantioselectivities.