Synthesis and characterization of 6-O-β-lactosyl-α,β-lactoses, 1-O-(6-O-β-lactosyl-β-lactosyl)-(R,S)-glycerols, and 4,6-di-O-β-D-galactopyranosyl-α,β-D-glucoses

Article abstract of DOI:10.1016/0008-6215(92)84058-Z

1,2,3,2',3',4',6'-Hepta-O-acetyl-β-lactose (4) was coupled with 2,3,6,2',3',4',6'-hepta-O-acetyl-α-lactosyl bromide (7) in the presence of Hg(CN)₂ to afford 1,2,3,2',3',4',6'-hepta-O-acetyl-6-O-(2,3,6,2',3',4',6'-hepta-O- acetyl-β-lactosyl)-β-lactose (11) which, upon O-deacetylation, gave 6-O-β-lactosyl-α,β-lactoses (64% from 4). In contrast, the reaction of 7 with benzyl 2,3,2',3',4',6'-hexa-O-acetyl-β-lactoside in the presence of Hg(CN)₂ produced 3,6,2',3',4',6'-hexa-O-acetyl-1,2-O-(2,3,2',3',4',6'-hexa-O-acetyl-1- O-benzyl-β-lactos-6-yl orthoacetyl)-α-lactose (63%) and 3,6,2',3',4',6'-hexa-O-acetyl-1,2-O-(1-cyanoethylidene)-α-lactose (27%). The glycosidation of 4 using 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide in the presence of Hg(CN)₂ afforded, after deprotection, 4,6-di-O-β-D-galactopyranosyl-α,β-D-glucoses (66%). The reaction of 11 with 1,2-di-O-benzyl-(R,S)-glycerols and trimethylsilyl trifluoromethanesulfonate yielded, after deprotection, 1-O-(6-O-β-lactosyl-β-lactosyl)-(R,S)-glycerols (18%). Under the same coupling conditions 11 reacted with 2-O-benzylglycerol to form 3-O-acetyl-2-O-benzyl-1-O-{2',3',4',6'-hexa-O-acetyl-6-O-(2,3,6,2',3' ,4',6'-hepta-O-acetyl-β-lactosyl)-β-lactosyl}-(R,S)-glycerols (16%). 1,2,3,2′,3′,4′,6′-Hepta-O-acetyl-β-lactose (4) was coupled with 2,3,6,2′,3′,4′,6′-hepta-O-Acetyl-α- lactosyl bromide (7) in the presence of Hg(CN)₂ to afford 1,2,3,2′,3′,4′,6′-hepta-O-acetyl-6-O-(2,3,6,2′,3$ PRM, 4′,6′-hepta-O-acetyl-6-O-(2,3,6,2′,3′, 4′,-hepta-O-acetyl-β-lactosyl)-β-lactose (11) which, upon O-deacetylation, gave 6-O-β-lactosyl-α,β-lactoses (64% from 4). In contrast, the reaction of 7 with benzyl 2,3,2′,3′,4′,6′-hexa-O-acetyl-β-lactoside in the presence of Hg(CN)₂ produced 3,6,2′,3′,4′,6′-hexa-O- acetyl-1,2-O-(2,3,2′,3′,4′,6′-hexa-O-acetyl-1-O-benzy l- β-lactos-6-yl orthoacctyl)-α-lactose (63%) and 3,6,2′,3′,4′,6′-hexa- O-acetyl-1,2-O-(1-cyanoethylidene)-α-lactose (27%). The glycosidation of 4 using 2,3,4,6-tetra-O-acetyl-α-D- galactoyranosyl bromide in the presence of Hg(CN)₂ afforded, after deprotection, 4,6-di-O-β-D- galactopyranosyl-α,β-D-glucoses (66%). The reaction of 11 with 1,2-di-O-benzyl-(R,S)-glycerols and trimethylsilyl trifluoromethanesulfonate yielded, after deprotection, 1-O-(6-O-β-lactosyl-β-lactosyl)-(R,S)-glycerols (18%). Under the same coupling conditions II reacted with 2-O-benzylglycerol to form 3-O-acetyl-2-O-benzyl- O-{2′,3′,4′,6′-hexa-O-acetyl-6-O-(2,3,6,2′,3 ′, 4′,6′-hepta-O-acetyl-β-lactosyl)-β-lactosyl}-( R,S)- glycerols (16%).