Visible light mediated homo- and heterocoupling of benzyl alcohols and benzyl amines on polycrystalline cadmium sulfide

Abstract

The oxidative coupling of sp3 hybridized carbon atoms by photocatalysis is a valuable synthetic method
as stoichiometric oxidation reagents can be avoided and dihydrogen is the only byproduct of the reaction.
Cadmium sulfide, a readily available semiconductor, was used as a visible light heterogeneous
photocatalyst for the oxidative coupling of benzyl alcohols and benzyl amines by irradiation with blue
light. Depending on the structure of the starting material, good to excellent yields of homocoupling
products were obtained as mixtures of diastereomers. Cross-coupling between benzyl alcohols and benzyl
amines gave product mixtures, but was selective for the coupling of tetrahydroisoquinolines to
nitromethane. The results demonstrate that CdS is a suitable visible light photocatalyst for oxidative bond
formation under anaerobic conditions.