Abstract: The author studied the mechanism of Cucatalyzed three\|component decarboxylative coupling reaction of glyoxylic acid, an amine and an alkyne by using the density functional theory methods. First, the reaction  mechanism proposed in experiments was calculated, and then a new reaction mechanism was proposed and calculated involving the coordination of the iminium salt, in situ formed from the glyoxylic acid and the amine, decarboxylation, alkyne coordination and insertion, protonation, nucleophilic addition, ligand exchange steps. The results of theoretical calculation show that the ratedetermining step of the mechanism is the insertion of the alkyne, and the energy barrier of reaction is 129.8 kJ/mol, which is in agreement with the result of experimental reaction temperature of 110 ℃.

Key words: coppercatalyzed, reaction mechanism, decarboxylative coupling reaction, density functional theory, threecomponent reaction