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

Hantzsch ester is a widely used organic reductant. We describe a new use of this classical reductant in visible-light-induced desulfurative coupling of alkyl benzothiazolyl sulfides with electron-deficient alkenes/alkynes through activation with base additives. The C(sp3)-S scission has been achieved in two independent ways, catalyst-free Hantzsch ester anion-mediated reaction and organo-photocatalysis. The synthetic utility is illustrated with several examples of the derivatization of natural products including monosaccharides. The mechanistic investigation has revealed that Hantzsch ester anion works as a photoreductant in the catalyst-free reaction, whereas it is included as a sacrificial reductant in the organo-photocatalysis.