Trapping of Isocyanates with Benzotriazole in situ - Preparation of Carbamoyl Benzotriazoles as an Isocyanate Alternative via Curtius Rearrangement

N-Aryl and N-alkenyl carbamoyl benzotriazoles were prepared in good to excellent yields from acyl azides and benzotriazole via Curtius rearrangement, while N-alkylcarbamoyl benzotriazoles were formed from N-alkanoyl benzotriazoles and sodium azide in one pot. The carbamoyl benzotriazoles can be used as a stable isocyanate alternative, as has been demonstrated by its reaction with amines to synthesize ureas in excellent yields.