RESUMO
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]