Visible-light photocatalytic selective oxidation of amine and sulfide with CsPbBr3 as photocatalyst

Abstract

Using a readily accessible and high-efficiency photocatalyst for inducing chemical transformations is highly desirable. All inorganic lead halide perovskites (APbX₃, X = Cl, Br, I) are utilized intensively in photovoltaics providing outstanding optoelectronic performance and are easy-to-process, but their use in organic synthesis is still in its infancy. Herein, we report a facile protocol for the photocatalytic oxidation of a series of amines and sulfides to their corresponding imines and sulfoxides with excellent yields and selectivity using CsPbBr₃ as a visible-light catalyst. The result show that amines bearing electron-donating groups give rise to aldehydes as the final products, while amines with electron-withdrawing groups afford imines as the major products. Reaction mechanism studies reveal that the photogenerated holes (h⁺), superoxide radicals (O₂˙⁻) and singlet oxygen are involved in the reaction performed in air and O₂ atmospheres. In addition, for the reaction conducted under anaerobic conditions, free radicals generated by amines plays a vital role in determining the transformation of amines to imines.