Phosphine-Catalyzed [3 + 2] Annulation of Morita-Baylis-Hillman Carbonates with Isoxazole-Based Alkenes.

A phosphine-catalyzed [3 + 2] annulation of Morita-Baylis-Hillman (MBH) carbonates with 3-methyl-4-nitro-5-styrylisoxazoles has been developed to afford various multifunctional isoxazoles in moderate to good yields with moderate to excellent diastereoselectivities. With a spirocyclic chiral phosphine as the catalyst, up to 89% ee was obtained.