A NEW APPROACH TO C-BRANCHED MONOSACCHARIDES BY THE STEREOSELECTIVE HYDRODESULFURIZATION OF METHYL ENE]-3-DEOXY-ALPHA-D-ERYTHRO-HEXOPYRANOSID-2-ULOSE

The stereoselective reduction of methyl ne]-3-deoxy-alpha-D-erythro-he xo-pyranosid-2-ulose 1 with sodium tetrahydridoborate and tributyltin hydride, respectively, to (Z)-configured 4 is described. The increased reactivity of 4 compared to 1 is reflected in several substitution re actions resulting in the displacement of the methylthio group by diffe rent N nucleophiles. The substitution products 6-8 were stereoselectiv ely obtained as (Z) isomers. Pyrano[3,4-c]pyrazole derivatives 3 and 1 0 were prepared by treatment of 1 and 4, respectively, with hydrazine hydrate.