Synthetic potential inherent in D-isoascorbic acid as a precursor for pyridazine and furo[3,2-c]pyridazine ring systems with two asymmetric centers

Reaction of D-erythro-2,3-hexodiulosono-1,4-lactone-2,3-bis(phenylhydrazone ) (2) with an iodine, triphenylphosphine and imidazole mixture afforded the furo[3,2-c]pyridazine derivative 11. Condensation of 6-bromo-6-deoxy-D-ery thro-2,3-hexodiulosono-1,4-lactone with phenylhydrazine gave the bishydrazo nes 6, and 8 or the furo[3,2-c]pyridazine (11) depending on the reaction co nditions. The lactone ring in 11 could be opened by treatment with alkali t o give the pyridazine derivative 9. Lactonization of the later with simulta neous acetylation by acetic anhydride afforded the lactone derivative 14. A lkali treatment of 6 gave the pyrazolindione derivative 13 that gave upon r eation with HBr/AcOH the dibromide 15. The assigned structures were based o n spectral analysis. The activity of compounds 11 and 14 against hepatitis B virus has been studied.