Visible‐Light‐Induced Desulfurative Coupling of Alkyl Benzothiazolyl Sulfides with Electron‐Deficient Alkenes/Alkynes: Dual Role of Base‐Activated Hantzsch Esters

Abstract Hantzsch ester (HEH) is a bench‐stable compound used in hydrogenation and photoinduced reactions, where it acts as a photoreductant and an electron donor. In this study, we describe a new use of this classical reductant in the visible‐light‐induced desulfurative coupling of alkyl benzothiazolyl sulfides with electron‐deficient alkenes/alkynes via activation with base additives. C(sp 3 )─S scission is achieved through catalyst‐free HEH anion‐mediated reactions and organo‐photocatalysis. The synthetic utility is illustrated with several examples of derivatization of natural products, including monosaccharides. In addition, mechanistic investigations reveal that the HEH anion acts as a photoreductant in catalyst‐free reactions and as a sacrificial reductant in the organo‐photocatalysis.