Switchable divergent organocatalytic asymmetric reactions of azlactones with 1,4-enediones†

Highly selective asymmetric divergent reactions of azlactones with 1,4-enediones were accomplished. Catalyst-controlled diastereodivergent construction of bicyclic furofurans was successfully achieved via a Michael/acetalization/lactonization cascade reaction. Additionally, a series of Michael addition products were obtained by tuning substrates. Either fused bicyclic furofurans or Michael addition products were obtained in ideal yields with good to excellent stereoselectivities. Furthermore, bicyclic furofurans could be utilized in a series of synthetic transformations. This work realized the precise control of chemoselectivity, diastereoselectivity, and enantioselectivity simultaneously in a reaction and provided a valuable platform that furnishes structurally diverse molecules for multiple purposes using simple starting materials.