A Particularly Convenient One-Pot Synthesis of N-Alkoxycarbonyl, N-Acyl and N-Aroyl Substituted Iminophosphoranes; Improved Preparation of Azidoformates, Aroyl and Alkanoyl Azides; An Alternative Route to Complex Amides

Chloroformates and acid chlorides react smoothly with sodium azide in acetone at 0°C, forming azidoformates, aroyl and alkanoyl azides in very high yield. With triphenylphosphine or other phosphines present in the reaction mixture, the forming azides are intercepted, leading directly to the corresponding N-alkanoyl, N-aroyl, N-alkoxycarbonyl, and N-aryloxycarbonyliminophosphoranes. N-acylliminophos-phoranes react with n-butyllithium forming anions which react readily with electrophiles, e.g., carbonyl compounds, forming highly substituted iminophosphoranes. The phosphonium group is effortlessly removed from the latter compounds by acid hydrolysis forming the corresponding amides in high yield.