Palladium-Catalyzed Carbonylation of Amines with Mo(CO)6 as the Carbonyl Source

Catalytic carbonylation of transition metals is widely used as an effective means to synthesize carbonyl-containing compounds. In this article, we introduce a method for the synthesis of N,N′-diphenyl urea and N-phenyl carbamate by transition-metal-catalyzed carbonylation. Here, we use Mo(CO)6 as a safe and stable carbonyl source to introduce the reaction to produce carbonylation products and achieve the selective formation of N,N′-diphenylurea and N-phenylcarbamate under mild conditions. Mechanistic investigations suggested that the reaction proceeded through sequential amine C–H bond activation, carbonyl insertion, nucleophilic attack, and oxidation of Pd(0) with Cu(OAc)2 to generate N-phenyl carbamate and N,N-diphenyl urea products. Moreover, the indenones obtained with Mo(CO)6 as a CO surrogate can be functionalized to form synthetic useful derivatives via an environmentally friendly way.