Borbás A, Lipták A
Department of Biochemistry, L. Kossuth University, Debrecen, Hungary.
Carbohydr Res. 1993 Mar 17;241:99-116. doi: 10.1016/0008-6215(93)80099-z.
The key intermediates for the synthesis of p-trifluoroacetamidophenyl O-(3,6-di-O-methyl-beta-D-glucopyranosyl)-(1-->4)-O-(2,3-di-O-methyl-alp ha-L- rhamnopyranosyl)-(1-->2)-3-O-methyl-alpha-L-rhamnopyranoside (15), as well as p-trifluoroacetamidophenyl O-(3,6-di-O-methyl-beta-D- glucopyranosyl)-(1-->4)-2,3-di-O-methyl-alpha-L-rhamnopyranoside (29), were the methyl and ethyl O-(2-O-benzyl-4,6-O-benzylidene-3-O-methyl-beta- D-glucopyranosyl)-(1-->4)-2,3-O-diphenylmethylene-1-thio-alpha-L- rhamnopyranosides (10 and 24). Dichloroalane treatment of 10 and 24 removed the diphenylmethylene group, liberating HO-2 and HO-3 of the rhamnopyranoside residue, and opened the benzylidene acetal regioselectively to give the 4-O-benzyl-glucopyranosyl disaccharides. Methylation of the free OH groups resulted in the tetra-O-methyl 1-thio disaccharides (12 and 26), useful as glycosyl donors. Introduction of these temporary blocking groups allowed a drastic reduction in the number of synthetic steps to the target compounds.
对三氟乙酰氨基苯基 O-(3,6-二-O-甲基-β-D-吡喃葡萄糖基)-(1→4)-O-(2,3-二-O-甲基-α-L-鼠李吡喃糖基)-(1→2)-3-O-甲基-α-L-鼠李吡喃糖苷（15）以及对三氟乙酰氨基苯基 O-(3,6-二-O-甲基-β-D-吡喃葡萄糖基)-(1→4)-2,3-二-O-甲基-α-L-鼠李吡喃糖苷（29）合成的关键中间体是甲基和乙基 O-(2-O-苄基-4,6-O-亚苄基-3-O-甲基-β-D-吡喃葡萄糖基)-(1→4)-2,3-O-二苯基亚甲基-1-硫代-α-L-鼠李吡喃糖苷（10 和 24）。用二氯铝烷处理 10 和 24 可除去二苯基亚甲基基团，释放出鼠李吡喃糖苷残基的 HO-2 和 HO-3，并区域选择性地打开亚苄基缩醛，得到 4-O-苄基-吡喃葡萄糖基二糖。游离羟基的甲基化得到四-O-甲基 1-硫代二糖（12 和 26），可用作糖基供体。引入这些临时保护基团可大幅减少合成目标化合物的步骤数。
