Studies on dehydaro-d-erythro-and l-threo-ascorbic acid 2-arylhydrazone-3-oximes and mixed bishydrazones: conversion into substituted triazoles and pyrazolinediones

Reaction of p-nitrophenyltriazole of dehydro-D-erythro-ascorbic acid [I] with hydrazine hydrate in MeOH yielded the corresponding triazole hydrazide [II] which gave the triacetyl derivative [III]. Periodate oxidation of [II] gave the 3-formyltriazole derivative [IV] which formed a triacetyl derivative [VI]. The 3-formyl derivative [IV] was condensed with hydrazine hydrate and O-phenylenediamine to give compounds [VII] and [VIII], respectively. Treatment of [I] with ammonium hydroxide solution and MeOH gave the triazole carboxamide [IX] which produced two different acetyl derivatives [X] and [XI]. The p-nitrophenylhydrazone zone of dehydro-D-erythro-[XII] and dehydro-L- threo-ascorbic acid [XIII], reacted with phenylhydrazine to give the mixed bisarylhydrazones [XIV] and [XV], respectively, which formed the diacetyl derivatives [XVI] and [XVII]. Compound [XIV] underwent rearrangement to the corresponding pyrazole derivative [XVIII] which gave the acetyl product [XIX]. Periodate oxidation of [XVIII] gave the 3-formylpyrazole [XX] which yielded different condensation products [XXI]-[XXV]. Cupric chloride oxidation of [XV] gave the 3,6-anhydro derivative [XXVI] which characterized as its monoacetyl derivative [XXVII]

Reduction products and bromodeoxy derivatives of dehydro-L-ascorbic acid 2- [phenylhydrazone]

Dehydro-L-ascorbic acid 2-[phenylhydrazone] [I] was reduced by sodium borohydride to 3,6-anhydro-L-xylo-2-hexulosono-1,4-lactone-2- [phenylhydrazone] [II] which gave a mono-O-acetyl- and mono-O-benzoyl derivatives III and IV, respectively. Treatment of I with HBr/AcOH gave the 5,6-dibromo-5,6-dideoxy derivatives VI that gave a number of condensation products VII-XI, while treatment of I with methylhydrazine gave 1-methyl-3-[2,3-dibromo-2,3-dideoxy-L-threo- glycerol-1-yl]- 4,5-pyrazolinedione-4-[phenylhydrazone] [XII]