A facile synthesis of N,N′-disubstituted ureas from amide and amine by using N-bromophthalimide (NBP) and silveracetate in one pot

Various N,N′-disubstituted ureas5 were easily prepared from the corresponding primary amide1 by tratment with N-Bromophthalimide (NBP)-AgOAc-RNH2 4 in dry N,N-dimrthylformamide (DMF). This reaction envolved the intermediate formation of isocyanate3 from amide1 via Hofmann rearrangement by treatment with AgOAc and NBP and nucleophilic addition of amine4 to this isocyante3. This method is simple enough to be applied to the synthesis of various N,N′-disubstututed ureas in large scale conviently.