Organocatalytic Enantioselective [1 + 4] Annulation of Morita-Baylis-Hillman Carbonates with Electron-Deficient Olefins: Access to Chiral 2,3-Dihydrofuran Derivatives.Org Lett. 2017 09 15; 19(18):4774-4777.OL
A reaction has been developed for the chiral phosphine-catalyzed enantioselective [1 + 4] annulation of Morita-Baylis-Hillman carbonates with electron-deficient olefins via a Michael alkylation process. Morita-Baylis-Hillman carbonates reacted smoothly with β,γ-unsaturated α-keto ester and α,β-unsaturated ketone substrates under 1,2-bis[(2R,5R)-2,5-dimethylphospholano]benzene monoxide catalysis to furnish a wide range of optically active 2,3-dihydrofurans in high yields (up to 95%) with excellent asymmetric induction (up to >99% ee, >20:1 dr). This protocol represents an efficient strategy for the synthesis of optically active multifunctional 2,3-dihydrofurans via an asymmetric Michael alkylation domino reaction.