Highly Efficient and Regioselective Synthesis of N-Acyl Protected 2-Aminoacrylates through a PPh3-Catalyzed Reaction of Alkyl Propiolates with Amides

A simple and convenient strategy for the synthesis of N-acyl protected 2-aminoacrylates via PPh3-catalyzed reaction of alkyl propiolates with amides has been developed. This protocol is rapid and highly regioselective to provide various N-acyl protected 2-aminoacrylates in high yields (up to 95 %). The chemical structure of the product was determined by X-ray single-crystal structure analysis. In contrast, 3-sulfonamidoacrylates were obtained by Cs2CO3-catalyzed reactions of alkyl propiolates with secondary sulfamides. Moreover, synthetic utility of this method was further highlighted in the late-stage modification of drug molecules.