2-Ethynylpyridine-Promoted Rapid Copper(I) Chloride Catalyzed Azide-Alkyne Cycloaddition Reaction in Water

The copper(I) chloride catalyzed reaction of azides with alkynes in water at room temperature was promoted by the addition of a catalytic amount of 2-ethynylpyridine, affording the corresponding 1,4-disubstituted 1,2,3-triazoles in good yields after a specific reaction time. The catalytic system could be successfully applied to electron-rich, electron-poor, and sterically crowded substrates. A study of the additive effect of pyridine derivatives revealed that alkynyl and 2-pyridyl groups were essential for activating the copper catalyst.