Metallaphotoredox-Catalyzed Three-Component Couplings for Practical Synthesis of Ureas and Carbamates

Ureas are widely used in drugs, materials and catalysts because of their diamide structure, which can form strong hydrogen bonds. Therefore, it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds, especially unsymmetrical ureas. Here, we have disclosed novel and highly efficient three-component coupling reactions of organic halides, sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas. The reaction features simple and safe operations, broad substrate scopes, and product diversities. It allows the facile synthesis of N-aryl/vinyl ureas from readily available, user-friendly feedstocks under mild conditions (27 examples, 36%-98% yields). In addition, this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates (15 examples, 40%-95% yields). The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.