HETEROCYCLIC-DERIVATIVES OF SUGARS - AN NMR-STUDY OF THE FORMATION OF1-GLYCOSYL-3,5-DIMETHYL-1H-PYRAZOLES FROM HYDRAZONES

Hydrazones were prepared by treatment of monosaccharides and disacchar ides with hydrazine hydrate and converted in high yield to mixtures of 1-glycosyl-3,5-dimethyl-1 H-pyrazoles by reaction with pentan-2,4-dio ne (acetylacetone). The isomeric products were separated by HPLC and c haracterized by NMR spectroscopy. This represents a new approach to th e introduction of a heteroaromatic label into sugars under nonacidic a nd nonreducing conditions, and it is a process likely to be especially useful for glycan hydrazones obtained from glycoproteins by hydrazino lysis or beta elimination in the presence of hydrazine. (C) 1997 Elsev ier Science Ltd.