Palladium-catalyzed enantioselective [5 + 4] annulation of ortho-quinone methides and vinylethylene carbonates

Abstract

Highly enantioselective [5 + 4] annulation of ortho-quinone methides with vinylethylene carbonates has been developed by asymmetric palladium catalysis. The reaction allows for efficient synthesis of various nine-membered benzodioxonines in good yields (up to 88%) with high enantioselectivity (up to 98%). Mechanistic studies indicate that the [5 + 4] annulation occurs through an unusual action of chiral phosphine and achiral palladium catalysts.