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Condensed 1,2,3-triazoles (review)

“…As already mentioned, the intramolecular interaction of the cyano and amino groups under basic conditions provides a convenient approach to the synthesis of heterocycles. In [126] it was proposed to use the method for the production of condensed mesoionic triazole-containing heterocycles 220 starting from alkylated triazoles 221. The methods for the synthesis of triazole-containing heterocyclic systems described in the review are extremely diverse.…”

Synthesis of [1,2,3]Triazolo[1,5-a]Pyrazinium-3-Olates*

“…Previously we have shown [10-12] that alkylation of 1-aryl-and 1-arylmethyleneamino-1,2,3-triazol-5-olate sodium salts with alkyl halides leads to the zwitterionic 3-alkyl-1,2,3-triazol-3-ium-5-olate and [1,2,3]triazolo[1,5-а]pyrazinium-3-olate. In a continuation of our research in the field of mesoionic heterocycles [13][14][15][16], in this work we present the synthesis of new [1,2,3]triazolo[1,5-a]pyrazinium-3-olate derivatives.The geometry of 3-phenacyl-and 3-cyanomethyl derivatives of triazolium-5-olates 1а-с [10-12] indicates a possible interaction of carboxamide group nitrogen atom at position 4 of the triazole ring with keto or cyano groups, forming a condensed zwitterionic triazolopyrazine. Indeed, refluxing of 3-cyanomethyl derivatives 1a-c with sodium ethoxide for 5 h resulted in good yields (up to 80%) of the individual bicyclic compounds 2a-c.…”

“…Previously we have shown [10][11][12] that alkylation of 1-aryl-and 1-arylmethyleneamino-1,2,3-triazol-5-olate sodium salts with alkyl halides leads to the zwitterionic 3-alkyl-1,2,3-triazol-3-ium-5-olate and [1,2,3]triazolo[1,5-а]pyrazinium-3-olate. In a continuation of our research in the field of mesoionic heterocycles [13][14][15][16], in this work we present the synthesis of new [1,2,3]triazolo[1,5-a]pyrazinium-3-olate derivatives.…”

“…Compounds 1b,с, 5a,c,f were synthesized by a published method [11], the triazole 1a and pyrazinolate 2а were obtained according to another reference [16]. Preparation of [1,2,3]Triazolo[1,5-a]pyrazinium-3-olates 2a-c -cyanomethyl-1Н-1,2,3-triazolium-5-olate 1а-с (0.6 mmol) and sodium ethoxide, prepared from sodium metal (0.014 g, 0.6 mmol) in ethanol (25 ml), was refluxed for 5 h, cooled to room temperature, the precipitate formed was filtered off and recrystallized from ethanol.…”