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

ABSTRACT

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