Photocatalytic synthesis of (un)symmetrical ureas and benzimidazolones from amines and CS2.

• A novel photocatalytic synthesis of (un)symmetrical ureas and benzimidazolones has been developed. • Carbon disulfide and oxygen serve as the carbonyl sources, eliminating the need for additional oxidants. • Control experiments with oxygen-18 labeling have been conducted to propose a reaction mechanism. • The study contributes to green chemistry by offering an environmentally friendly approach to urea synthesis. A novel photocatalytic urea synthesis strategy is proposed for the preparation of ureas from amines and carbon disulfide (CS 2), with Rhodamine B utilized as the photocatalyst. Conducted under mild reaction conditions, this method does not require the use of extra oxidants and efficiently yields a series of (un)symmetrical ureas and benzimidazolones under blue light irradiation. Furthermore, control experiments with oxygen-18 labeling have been conducted, which demonstrate that the carbonyl oxygen in the urea products is predominantly derived from the oxygen in the air through an oxidative desulfurization process. [Display omitted] [ABSTRACT FROM AUTHOR]