Studies on dehydro-l-ascorbic acid 3-oxime 2-phenylhydrazone: Conversion into substituted triazoles

l-threo-2,3-Hexodiulosono-1,4-lactone 3-oxime 2-(phenylhydrazone) (1) gave 2-(p-bromophenyl)-4-(l-threo-1,2,3-trihydroxypropyl)-1,2,3-triazole-5-carboxylic acid 5,1¹-lactone (2), and this gave a diacetyl and a dibenzoyl derivative. On treatment of 2 with liquid ammonia, methylamine, or dimethylamine, the corresponding triazole-5-carboxamides (5–7) were obtained. Periodate oxidation of 5 gave 2-(p-bromophenyl)-4-formyl-1,2,3-triazole-5-carboxamide (10), and, on reduction, 10 gave 2-(p-bromophenyl)-4-(hydroxymethyl)-1,2,3-triazole-5-carboxamide, characterized as its monoacetate. Condensation of 10 with phenylhydrazine gave the triazole hydrazone. Acetonation of 2 gave the isopropylidene derivative. Reaction of 2 with HBr-HOAc gave 4-(l-threo-2-O-acetyl-3-bromo-1,2-dihydroxypropyl)-2-(p-bromophenyl)-1,2,3-triazole-5-carboxylic acid 5,1¹-lactone. Similar treatment of 1 with HBr-HOAc gave 5-O-acetyl-5-bromo-6-deoxy-l-threo-2,3-hexodiulosono-1,4-lactone 3-oxime 2-(phenylhydrazone). This was converted into 4-(l-threo-2-O-acetyl-3-bromo-1,2-dihydroxypropyl)-2-phenyl-1,2,3-triazole-5-carboxylic acid 5,1¹-lactone on treatment with boiling acetic anhydride. On reaction of 1 with benzoyl chloride in pyridine, dehydrative cyclization occurred, with the formation of 4-(l-threo-2,3-dibenzoyloxy-1-hydroxypropyl)-2-phenyl-1,2,3-triazole-5-carboxylic acid 5,1¹-lactone, which was converted into the amide on treatment with ammonia.