Copper(I)‐Catalyzed Three‐Component Reaction of Terminal Propargyl Alcohols,Aldehydes, and Amines: Synthesis of 3‐Amino‐2‐pyrones and 2,5‐Dihydrofurans

A novel copper(I)‐catalyzed three‐component reaction for the efficient synthesis of 3‐amino‐2‐pyrones and 2,5‐dihydrofurans from propargyl alcohols, aldehydes, and amines has been developed. The starting materials are easily available and the scope of this method is broad. Through mechanistic studies, it is believed that the three‐component reaction consists of an A³‐coupling to propargylic amine, alkyne–allene isomerization, and intramolecular cyclization of the allenol to form a furan. In case of using ethyl glyoxalate as the aldehyde, a ring‐opening, lactonization, and isomerization process affords the 3‐amino‐2‐pyrones.