Studies on dehydro-l-ascorbic acid 2-arylhydrazones: conversion into substituted triazoles and pyrazolinediones

The 2-p-chlorophenylhydrazone of dehydro-L-ascorbic acid was reacted with hydroxyamine giving the 3-oxime. Dehydrative cyclization of the latter gave the triazole derivative. The lactone ring cleaved upon treatment with hydrazine, methylamine or dimethylamine giving the corresponding triazole carboxamide derivative. Periodate oxidation of the triazole carboxamide gave the 3-formyltriazole which upon reduction gave the corresponding alcohol, characterized as its monoacetate. The 2-hydrazone was condensed with arylhydrazine giving the mixed bis- hydrazones, which underwent rearrangement to the pyrazolinediones and gave the bicyclic 3,6-anhydro derivatives upon treatment with cupric chloride