Heterocyclic derivatives of sugars: the formation of 1-glycosyl-3-methylpyrazol-5-ones from hydrazones

Conditions to effect the conversion of monosaccharide and disaccharide hydr azones to 1-glycosyl-3-methylpyrazol-5-ones were examined. The sugar pyrazo lone derivatives were sensitive to oxidation, but high yields were achieved with 2,2,2-trifluoroethyl acetoacetate in mildly acidic solution. Azo coup ling of the pyrazolones produced highly coloured azopyrazolone derivatives that prevented further degradation, and these may prove useful labels for c hromatographic analysis of carbohydrates. (C) 2000 Elsevier Science Ltd. Al l rights reserved.