Studies on dehydro-l-ascorbic acid 2-nitrophenyl-hydrazone: conversion into pyrazolinedione and thiadiazoline derivatives

The p-nitrophenylhydrazone of dehydro-L-ascorbic acid [I] reacted with methylhydrazine in MeOH giving the pyrazolinedione [V] and not the expected mixed bishydrazone [III]. The pyrazole derivative gave the tri-O-acetyl and tri-O-benzoyl derivatives [VI] and [VII], respectively. Periodate oxidation of [V] gave the 3-arboxaldehyde derivative [VIII] which was reduced by NaBH4 to the corresponding alcohol [IX] which formed the monoacetyl derivative [X]. The 3-carboxaldehyde condensed with hydroxylamine to give the 3-hydroxyiminomethyl derivative [XI], which upon acetylation gave the 3-acetoxyiminomethyl derivative [XII]. Similarly, benzoylation of [XI] gave the 3-benzoyl derivative [XIII]. The 3-thiosemicarbazone [XIV] of [VIII] gave the bicyclic derivative [XV] upon treatment with benzoyl chloride in pyridine. Treatment of [XV] with hydrazine hydrate gave [XVII]. which upon benzoylation gave [XVIII]

on the rearrangement of dehydro-L-ascorbic acid mixed bishydrazone to 4,5-pyrazolinediones

Dehydro-L-ascorbic acid 2-[p-nitrophenylhydrazone] [I] reacted with p- sulfamylphenylhydrazine giving the mixed bishydrazone II, which gave the di-O-acetyl- and di-O-benzoyl derivatives III and IV. II underwent rearrangement by hydrazine hydrate to the pyrazole derivatives VI and VII. Periodate oxidation of V gave the 3-carboxaldehyde derivative VIII, which was reduced by sodium borohydride to the corresponding alcohol IX that gave monoacetyl derivative X. Compound VIII gave a number of condensation products XI-XVII. Mild oxidation of II with cupric chloride gave the 3,6-anhydro derivative XVIII that gave the monoacetyl and monobenzoyl derivatives XIX and XX, respectively. Acetylation of the 3-hydroxyiminomethyl derivative XI gave the 3-acetoxyiminomethyl derivative XXI. Similarly, benzoylation of XI gave the 3-benzoyl derivative XXII. The 3-thiosemicarbazone XVII, gave the bicyclic derivative XXIII upon acetylation. Similarly, benzoylation of XVII gave XXIV

Some reactions of 3-formyl-4,5- [1H] pyrazolinedione-4- [phenylhydrazone]

The 3-hydroxyiminomethylpyrazole derivative II existed in ketoenol as evidenced by the production of two acetyl derivatives IV and V, respectively. The enol form III gave the benzoyl derivative VI. Treatment of III with benzoyl chloride in pyridine, for a long time, gave the bicyclic derivative VII. The 3-thiosemicarbazone derivative also existed in ketoenol forms. Both gave the acetyl bicyclic derivatives X and XI upon acetylation. The enol form IX also formed the benzoyl bicyclic derivative XII. The 3-formyl derivative I condensed with hydrazine hydrate and methylhydrazine to give the corresponding hydrazones XIII and XIV, characterized by giving the acetyl derivatives XVII and XVIII, respectively

Some heterocycles from dehydro-l-ascorbic acid bishydrazones

Controlled reaction of dehydro-L-ascorbic acid [I] with one mole of o- tolylhydrazine gave the 2-[o-tolyl] hydrazone II. The reaction of II with phenyl- and o-tolylhydrazine afforded the bis-hydrazones III and V, which underwent acetylation to the di-O-acetyl derivatives IV and VI, respectively. Oxidative cyclization of III and V with cupric chloride gave the 3,6-anhydro derivatives XIII and XV, respectively. The bishydrazone III underwent rearrangement to the pyrazolodione VII by the action of alkali, followed by acidification. Treatment of VII with acetic anhydride in pyridine afforded the tri-O-acetyl derivative VIII. Periodate oxidation of VII led to the aldehyde IX, which was converted to the pyrazole oxime XIX and thiosemicarbazone XXII by treatment with hydroxylamine and thiosemicarbazide, respectively. Acetylation of XXII by boiling with acetic anhydride yielded the thiazoline XXII. Compound II underwent dehydrative acetylation into compound XVII. The latter reacted with methylhydrazine to give XVIII. The IR and PMR of some of the compounds were investigated