Synthesis of 2,4,5,6-Tetrahydropyrrolo[1,2-c][1,2,3]triazolio-5-olate

Abstract

In continuing studies on condensed zwitterionic derivatives of 1,2,3-triazole [1-2], we proposed a simple and convenient method for synthesis of 1-imidazolylpyrrolo[1,2-c][1,2,3]triazolio-5-olate. By means of azo coupling of 5-diazoimidazole 1 with proline, we obtained triazene 2 [3], isolated as two isomers relative to the N=N bond. N N N + N NH O O EtO 2 C Me Ac 2 O Ac 2 O 1 2 3 4 5The reaction of intramolecular acylation in acetic anhydride leads to formation of pyrrolo[1,2c][1,2,3]triazolio-5-olate 3. Cyclization of triazene 4, obtained from p-tolyl-N-methylglycine and imidazole 1, leads to the zwitterionic triazole 5.The 1 H NMR spectra were taken in DMSO-d6, internal standard TMS. 1-(4-Ethoxycarbonylimidazol-1-yl)-2,4,5,6-tetrahydropyrrolo[1,2-c][1,2,3]triazolio-5-olate (3).A solution of sodium nitrite (0.186 g, 2.7 mmol) in water (10 ml) was added dropwise at 0-5°C with stirring to a solution of the ethyl ester of 5-aminoimidazole-4-carboxylic acid (0.21 g, 1.1 mmol) in 0.1 N HCl (27 ml). The end of the reaction was monitored using iodine/starch paper. The yellow solution of diazo compound 1 obtained __________________________________________________________________________________________

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.…”

“…Organic Materials, Collective Access Center of the Ural Federal University. 13 С NMR spectra were acquired without suppression of С-Н coupling. Mass spectra were recorded on a МАТ11 instrument (EI, 70 eV).…”