Palladium-catalyzed asymmetric [4+3] cycloaddition of acyclic α,β-unsaturated imines with trimethylenemethane donors: access to chiral non-fused azepines

We report herein a Pd-catalyzed asymmetric [4 + 3] cycloaddition of acyclic alpha,beta-unsaturated imines with trimethylenemethane (TMM) donors under mild conditions. A variety of non-fused azepines are obtained in good yields (up to 90% yield) with high enantioselectivity (up to 97% ee). The reaction features a broad substrate scope and good functional group tolerance, and the cyano-, benzoyl-, and amino-TMM donors are all suitable for this cycloaddition. An efficient approach for the construction of non-fused azepines in good yields with high enantioselectivity via Pd-catalyzed asymmetric [4 + 3] cycloaddition was developed.