Synthesis and properties of 1-(3,4-Di-O-acetyl-2-deoxy-2-hydroxyimino-D-threo-pentopyranosyl)pyrazoles

3,4-Di-O-acetyl-2-deoxy-2-nitroso-alpha -D-xylo-pentopyranosyl chloride (2) reacts with pyrazole to afford 1-[3,4-di-O-acetyl-2-deoxy-2-(Z)-hydroxyimino-alpha- (3) and beta -D-threo-pentopyranosyl]pyrazole (4). The products of condensation were modified at C-2 or C-3 to give pyrazole derivatives with 3-azido-2,3-dideoxy-2-hydroxyimino-pentopyranosyl (5,7,8,9,10), 2-acetoxyimino-2,3-dideoxy-beta -D-glycero-pentopyranosyl (12,13), beta -D-lyxo- (14), beta -D-xylopentopyranosyl (15) structures and 2,3-dihydro-2-pyrazol-1-yl-6H-pyran-3-one oximes (6,11). The conformation of the sugar residue and configuration at the anomeric centre and of the hydroxyimino group were established on the basis of H-1 NMR and polarimetric data.