In this work, the synthesis of novel triazole derivatives with barbituric motifs in good yields is described. The alkyne was prepared through the Knoevenagel reaction of barbituric derivatives with ortho and para O- propargylated hydroxyl-benzaldehyde. The mechanism and regioselectivity of this [3+2] cycloaddition (CA) reaction were investigated using the density functional theory (DFT) at the B3LYP/6-31+G(d) level of theory. The computational studies revealed that a di-copper catalyzed stepwise mechanism, involving six-membered ring intermediate, is the preferred pathway. The regioselectivity was explained in terms of frontier molecular orbital (FMO) interactions, local and global electrophilicity and nucleophilicity indices. 19 Accordingly, the favored interactions for di-copper acetylide are in good 20 agreement with the observed regioselectivity, while completely opposite results 21 were obtained for a possible uncatalysed reaction.
