A Facile Synthesis of N,N'-Disubstituted Ureas from Amide and Amine by Using N-Bromophthalimide (NBP) and Silvercetate in One Pot

Various N,N'-disubstituted ureas 5 were easily prepared from the corresponding primary amide 1 by tratment with N-Bromophthalimide $(NBP)-AgOAc-RNH$_{2}$ 4 in dry N,N-dimrthylformamide (DMF). This reaction envolved the intemediate formation of isocyanate 3 from amide 1 via Hofmann rearrangement by treatment with AgOAc and NBP and nucleophilic addition of amine 4 to this isocyante 3. This method is simple enough to be applied to the synthesis of various N,N'-disubstututed ureas scale conviently.