Mechanism of cyclisation of N-(1,2,4-triazol-3-yl)hydrazonyl bromides to mixtures of isomeric triazolotriazoles

Synthesis of 5-aryl-3-C-glycosyl- and unsymmetrical 3,5-diaryl-1,2,4-triazoles from alkylidene-amidrazones

“…9 Hydrazonoyl bromides XIII may be prone to loss of bromide ion to form carbocation XIV as it was made likely in kinetic studies of several hydrazonoyl halides. [38][39][40] Cation XIV may form the triazole V directly or via XII depending on the reaction conditions. The presence of this cation in the reaction mixtures may also account for the formation of the observed/isolated by-products.…”

“…General procedure IX for the synthesis of unsymmetrical 3,5disubstituted-1,2,4-triazoles (39,40) An arylidene amidazone (35 or 36, 0.331 mmol) was dissolved in CH 2 Cl 2 (10 mL), and NBS (0.059 g, 0.331 mmol) was added. The reaction mixture was stirred at room temperature.…”

“…General procedure X for the synthesis of unsymmetrical 3,5disubstituted-1,2,4-triazoles (39,40) An arylidene amidazone (35 or 36, 0.83 mmol) and ammonium acetate (0.13 g, 0.1.66 mmol) was dissolved in glacial AcOH (16 mL), then NBS (0.148 g, 0.83 mmol) was added. The mixture was stirred and heated at 110 C overnight.…”

“…arylidene-arenecarboxamidrazones(35,36) and 3,5-diaryl-1,2,4-triazoles(39)(40)(41) method constitutes the shortest synthetic route to 3-(b-Dglycopyranosyl)-5-substituted-1,2,4-triazoles, among which the glucose derivatives belong to the most efficient inhibitors of glycogen phosphorylase, and are thereby potential antidiabetic agents.…”