Studies on Dehydro-D-erythro-ascorbic acid 2-arylhydrazone 3-oximes: Conversion into Substituted Triazoles and Isoxazolones

Abstract

D- erythro-2,3-Hexodiulosono-1,4-lactone 2- o-bromophenylhydrazone (2) was prepared from dehydro-isoascorbic acid. Reaction of 2 with NH2OH gave the 2-hydrazone-3-oxime (3) which on boiling with Ac2O, gave the triazole derivative 4. The unacetylated triazole derivative 5 was obtained from 3 with Br2–H2O. Treatment of 4 or 5 with ammonia gave the triazole carboxamides 7 and 8 respectively. Vigorous acetylation of 7 and 8 with boiling Ac2O gave tetraacetates, while Ac2O/pyridine gave triacetates. Reaction of 3 with HBr–AcOH gave the 5- O-acetyl-6-bromo-6-deoxy derivative 14, and a controlled reaction of 3 with NaOH, followed by neutralisation, gave the isoxazolone 16.