Catalytic Asymmetric [3 + 2] Cycloaddition of Aromatic Aldehydes with Oxiranes by C—C Bond Cleavage of Epoxides: Highly Efficient Synthesis of Chiral 1,3-Dioxolanes.

A novel and efficient N,N′-dioxide–Gd(III) complex was developed for the highly diastereo- and enantioselective [3+2] cycloaddition of aryl oxiranyl diketones and aldehydes via C–C bond cleavage of oxiranes. The corresponding chiral 1,3-dioxolanes were obtained in excellent yields (up to 99%) with high diastereoselectivities (>95 : 5 dr) and enantioselectivities (up to 91% ee). Moreover, a possible transition model was proposed to explain the origin of the asymmetric induction.