C-(polyacetoxy)alkyloxadiazolines and related compounds

The (phenylacetyl)hydrazones of d-galactose, d-glucose, d-mannose, d-arabinose, l-arabinose, d-xylose, and l-sorbose were prepared. The d-galactose and d-arabinose derivatives were converted into their per-O-acetylated derivatives (8 and 9, respectively). The acyclic structure of 8 was proved from its direct preparation by the condensation of(phenylacetyl)hydrazine with penta-O-acetyl-aldehydo-d-galactose. Cyclization of 2,3,4,5,6-penta-O-acetyl-aldehydo-d-galactose (phenylacetyl)hydrazone with boiling acetic anhydride yielded a mixture of two products that could be separated by fractional recrystallization, to give 3-acetyl-5-benzyl-2-(polyacetoxy)alkyl-1,3,4-oxadiazolines; a mechanism for the reaction was proposed. The n.m.r. and mass spectra of some of these derivatives were discussed.