Enantioselective construction of tricyclic pyrrolidine-fused benzo[b]thiophene 1,1-dioxide derivatives via copper(i)-catalyzed asymmetric 1,3-dipolar cycloaddition

Abstract

A highly efficient copper(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with benzo[b]thiophene 1,1-dioxides as the dipolarophiles was developed, providing elegant access to novel chiral tricyclic pyrrolidine-fused benzo[b]thiophene 1,1-dioxide derivatives in good to excellent yields (up to 99%) with excellent diastereo- and enantioselectivities (up to >25 : 1 dr, up to 99% ee). Furthermore, the cycloadducts could be conveniently converted to synthetically important tricyclic pyrrolidine-fused benzo[b]thiophene and tetracyclic oxazolidin-2-one derivatives via simple transformations.