Copper‐Catalyzed Double Decarboxylative Coupling Reactions of Alkynyl Carboxylic Acid and Glyoxylic Acid: Synthesis of Propargyl Amines and Imidazopyridines

The reaction of alkynyl carboxylic acids, glyoxylic acid derivatives, and amines in the presence of a copper catalyst afforded the corresponding propargyl amines in good yields. The alkynyl carboxylic acid of this coupling reaction shows similar reactivity to that of a terminal alkyne, and the reactivity of the glyoxylic acid is almost identical to that of an aldehyde. When 2-aminopyridine was employed as the amine source, imidazopyridine derivatives were formed in good yields.