Convenient syntheses of 5-O- and 3,5-di-O-(β-D-galactofuranosyl)-D-galactofuranose

Article abstract of DOI:10.1016/0008-6215(90)84193-X

Benzoylation of D-galactono-1,4-lactone with 2.2 mol of benzoyl chloride, at -23 deg C, gave the 2,6-dibenzoate (2, 62percent).Tin(IV) chloride-catalyzed glycosylation of 2 with 1,2,3,5,6-penta-O-benzoyl-α,β-D-galactofuranose (1) afforded 2,6-di-O-benzoyl-5-O-(2,3,5,6-tetra-O-benzoyl-β-D-galactofuranosyl)-D-galactono-1,4-lactone (4, 70percent), HO-3 of which was benzoylated to give 5.The structure of 4 was confirmed by its conversion into crystalline β-D-Gal f-(1->5)-D-Gal-ol (8).Reduction of the lactone function of 5 with di-isoamylborane followed by debenzoylation gave β-D-Gal f-(1->5)-D-Gal f (7).A by-product of the condensation of 1 with 2 was characterized as 2,6-di-O-benzoyl-3,5-di-O-(2,3,5,6-tetra-O-benzoyl-β-D-galactofuranosyl)-D-galactono-1,4-lactone (9), which was converted, as for 5, into β-D-Gal f-(1->3)<β-D-Gal f-(1-<5)>-D-Gal f (13).