Amine-catalyzed synthesis of N2-sulfonyl 1,2,3-triazole in water and the tunable N2-H 1,2,3-triazole synthesis in DMSO via metal-free enamine annulation

The selective synthesis of N2-sulfonyl and N2-H 1,2,3-triazoles via organocatalytic annulation of enaminone/enaminoester with sulfonyl azide has been realized. The unconventional selectivity providing N2-sulfoyl 1,2,3-triazoles takes place in pure water, wherein the hydrogen bond effect between water and the intermediate resulting from enamine-azide corporation accounts for the novel reaction selectivity. On the other hand, the reactions conducted in DMSO specifically afford N2-H 1,2,3-triazoles in the absence of such hydrogen bond effect.