H-bond promoted NPh3-mediated SrTiO3-photocatalyzed cascade decarboxylative coupling/annulation of benzo[d]isothiazole 1,1-dioxides

Abstract

The first applying SrTiO3 semiconductor as a photocatalyst in organic synthesis and using NPh3 as a redox catalyst in photocatalysis was reported. With SrTiO3 as the heterogeneous photocatalyst, NPh3 as the homogeneous redox catalyst, H-bond as the promoter, paraformaldehyde as the cheap and atom economic methylene source, various 1,2,3,9b-tetrahydrobenzo[d]imidazo[1,5-b]isothiazole 5,5-dioxides can be efficiently synthesized through the visible-light-induced cascade decarboxylative coupling/annulation reaction.