Enantioselective synthesis of tetrahydroisoquinoline derivatives via chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition.

Abstract

An asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with α,β-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium complex has been developed. The corresponding C-1-substituted tetrahydroisoquinoline derivatives were obtained in high yields (>90%) with excellent stereoselectivities (up to 99% ee and >20 : 1 dr). The reaction can be conducted on a gram-scale using a low catalyst loading (0.5 mol%) with high yield and selectivity.