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A new approach to the synthesis of disaccharide derivatives having a furanose as the reducing unit

1989; Elsevier BV; Volume: 189; Linguagem: Inglês

10.1016/0008-6215(89)84087-x

1873-426X

Cecile du Mortier, Oscar Varela, Rosa M. de Lederkremer,

Enzyme Production and Characterization

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).