Trimethylsilylazide/KN3/18-Crown-6. Formation and Curtius Rearrangement of Acyl Azides from Unreactive Acid Chlorides

Abstract
Trimethylsilylazide (TMSA) has been reported as a safe, stable substitute for hydrazoic acid in the preparation of acyl azides from acid anhydrides and chlorides.1 Subsequent thermolysis of these acyl azides in situ has yielded isocyanates via the Curtius rearrangement.1,2