SYNTHESIS OF IDEOXY-BETA-D-ERYTHRO-HEX-2-ENOPYRANOSYL)PYRAZOLES FROM 3,4,6-TRI-O-ACETYL-D-GLUCAL

eta-D-erythro-hex-2-enopyranosyl)-2,4-pentanedione and its analogue th ro-hex-2-enopyranosyl)-1-phenyl-1,3-butanedione, prepared from -acetyl -1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol (3,4,6-tri-O-acetyl-D-gluc al), reacted with hydrazine and its methyl-, phenyl-, p-tolyl, and p-m ethoxyphenyl-derivatives in ethanol, at room temperature, to afford, i n 71-96% yields, a series of ta-D-erythro-hex-2-enopyranosyl)-3-methyl pyrazoles having the N-1 free or substituted by the foregoing groups, and the C-5 substituted by a methyl or phenyl group. The reactions of the 1-phenyl-1,3-butanedione derivative were highly regioselective. Ca talytic hydrogenation of some of these novel compounds gave the respec tive 4',6'-di-O-deprotected-2',3'-saturated compounds in 51-67% yields . The acetolysis/methanolysis of one of the title compounds led to the formation of the 4',6'-di-O-debenzylated 2',3'-unsaturated pyrazole C -nucleoside in poor yield. (C) 1998 Elsevier Science Ltd. All rights r eserved.