Multifunctional chiral phosphine-catalyzed [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones: asymmetric synthesis of 4-oxo-hexahydropentalenes

A multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo1,3-a, 4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (490% ee) were obtained for a series of substrates under mild reaction conditions.