Ferrocene-Mediated Photocatalytic Annulation of N-Sulfonyl Ketimines on a Polycrystalline WSe2 Semiconductor Photocatalyst

A merger of heterogeneous polycrystalline WSe2 semiconductor photocatalysis and homogeneous ferrocene redox catalysis for the cascade radical coupling-annulation reactions was established. In the redox-mediated photocatalysis, ferrocene can improve the separation of photogenerated hole–electron pairs on WSe2 by consuming the hole via the formation of a ferrocene cation, which triggered the molecular transformations. Various benzoeimidazo1,5-c1,2,3oxathiazine 5,5-dioxides were formed through semiheterogeneous three-component reaction of N-sulfonyl ketimines, N-arylglycines, and formaldehyde.