Enantioselective [3 + 2] annulation of tryptanthrin-derived ketimines and 2-naphthols: access to polycyclic indolo[2,1-b]quinazoline derivatives

Abstract

A highly enantioselective [3 + 2] annulation of tryptanthrin-derived ketimines and 2-naphthols with chiral phosphoric acid as a catalyst has been established. This method allows access to a series of optically pure dihydronaphthofuran-fused indolo[2,1-b]quinazoline derivatives with excellent yields and enantioselectivities (up to 99% yield and 99% ee). Moreover, the initial biological evaluation of the products in cell-based assays demonstrated their potential antitumor activity against leukemia cells.