SYNTHESIS AND (13)C-N.M.R. SPECTROSCOPY OF 2-O- AND 6-O-ACETYL-3-O-α-L-RHAMNOPYRANOSYL-D-GALACTOSE, CONSTITUENTS OF BACTERIAL CELL-WALL POLYSACCHARIDES

Article abstract of DOI:10.1016/S0008-6215(00)80773-9

Benzyl 2-O-acetyl-4,6-O-benzylidene-3-O-(2,3,4-tri-O-acetyl-α-L-rhamnopyranosyl)-β-D-galactopyranoside (11) has been synthesised by two routes.Partial deacetylation of 11 and then acid hydrolysis yielded benzyl 2-O-acetyl-3-O-α-L-rhamnopyranosyl-β-D-galactopyranoside, catalytic hydrogenolysis of which gave the first title compound in excellent yield.Benzyl 4,6-O-benzylidene-3-O-α-L-rhamnopyranosyl-β-D-galactopyranoside was benzylated, and hydrogenolysis (LiAlH4-AlCl3) of the product gave the disaccharide derivative 16 with only HO-6 unsubstituted.Acetylation of 16 followed by catalytic hydrogenolysis gave the crystalline, second title compound.As model compounds for comparative n.m.r. studies, 2-O-, 3-O-, and 6-O-acetyl-D-galactose were also synthesised.