Some heterocycles from dehydro-l-ascorbic acid bishydrazones

ABSTRACT

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