A NEW APPROACH TO THE SYNTHESIS OF DISACCHARIDE DERIVATIVES HAVING A FURANOSE AS THE REDUCING UNIT

Article abstract of DOI:10.1016/0008-6215(89)84087-X

The lactonic disaccharide 2,3,5-tri-O-benzoyl-6-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-D-galactono-1,4-lactone (7) was prepared by condensing 6-O-trityl-2,3,5-tri-O-benzoyl-D-galactono-1,4-lactone (2) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (4) or with 1,2,3,4,6-penta-O-acetyl-β-D-glucopyranose (6).The reaction was carried out using various catalysts.In the presence of silver trifluoromethanesulfonate or tin(IV) chloride, formation of the 1,2-trans glycosidic bond took place stereoselectively, to afford compound 7 in good yields.However, condensation of 2,3,5-tri-O-benzoyl-D-galactono-1,4-lactone (3) with 4 catalyzed by mercuric salts gave 3,4,6-tri-O-acetyl-1,2-O-<1(S)-(2,3,5-tri-O-benzoyl-D-galactono-1,4-lacton-6-yloxy)ethylidene>-α-D-glucopyranose (5) as the main product.Reduction of the lactone function of 7 with bis(3-methyl-2-butyl)borane led to 2,3,5-tri-O-benzoyl-6-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-β-D-galactofuranose (8).