Pd(II)/Ag(I)-Promoted One-Pot Synthesis of Cyclic Ureas from (Hetero)Aromatic Amines and Isocyanates

A simple and facile one-pot reaction has been developed to afford a diverse range of N,N′-disubstituted benzimidazolones and imidazopyridinones containing two differently substituted N atoms. A cooperative Pd­(II)/Ag­(I) system promotes the sequential addition/intramolecular C–H amidation reaction of (hetero)­aromatic amines and isocyanates, leading to the formation of two C–N bonds. A mechanism involving radical intermediates generated by single-electron transfer (SET) in the presence of a Ag2CO3 oxidant and Pd­(OAc)2 Lewis acid is proposed. This protocol offers an operationally easy, simple, and robust approach with the use of readily available starting materials, good functional group tolerance, and high efficiency.