Synthesis and Rearrangement of Mono and Bis-(p-Fluorophenyl)Hydrazones of Dehydro-L-Ascorbic Acid

The mono- and bis-(p-fluorophenyl)hydrazones of dehydro-L-ascorbic acid were prepared. Oxidation of the bis(hydrazone) afforded 3,6-anhydro-3-C-(p-fluorophenylazo) L- xylo -2-hexul osono-1,4-1 actone-2-( p -fluorophenyl)hydrazone. Rearrangement of the bis(hydrazone) gave T-( p -fluorophenyl)-3-(L- threo -glycerol-1-yl)-pyrazoli n-4,5-di one-4-( p -fluorophenyl)hydrazone, whose periodate oxidation gave 3-formyl-1-( p -fluorophenyl pyrazol in-4.5-dione-3-4-( p -fluorophenyl)hydrazone that upon reduction gave 1-( p -fluorophenyl)-3-hydroxymethyl pyrazol in-4,5-dione-4-( p -fluorophenyl)hydrazone. The compounds were characterized as their acetates and benzoates.