Rapid synthesis of acid azides via in situ generation of acid chlorides using CPICl as chlorinating agent from the corresponding N-alpha-protected amino acids is described. Also the conversion of acid azides into ureidopeptides through the Curtius rearrangement under ultrasonication is delineated. The mildness of the protocol renders the acid-sensitive substrates to afford the corresponding amino acid azides and ureidopeptides in good yields. Diphenylcyclopropenone has also been recovered from the reaction mixture and reused
