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

The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 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. [Display omitted] • Commercial SrTiO 3 semiconductor was firstly used for photocatalytic organic synthesis. • NPh 3 was firstly used as a redox catalyst in semiconductor photocatalysis. • Paraformaldehyde was used as the cheap and atom economic methylene source. • SrTiO 3 exhibits excellent photocatalytic activity for at least five catalytic cycles. The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 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. [ABSTRACT FROM AUTHOR]