Kovác P, Sklenár V, Glaudemans C P
NIDDK, National Institutes of Health, Bethesda, MD 20892.
Carbohydr Res. 1988 Apr 15;175(2):201-13. doi: 10.1016/0008-6215(88)84143-0.
Methyl 6-O-(6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl)-2,3,4-tri- O-benzyl-alpha-D-glucopyranoside (5) was formed with high stereoselectivity when the condensation of methyl 2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl (1) with 6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl chloride in ether was promoted with silver perchlorate in the presence of 2,4,6-trimethylpyridine. O-Deacetylation of 5, followed by treatment of the formed 6, containing only HO-6' unsubstituted, with diethylaminosulfur trifluoride (DAST) or dimethylaminosulfur trifluoride (methyl DAST) gave the per-O-benzyl derivative (9) of methyl 6'-deoxy-6'-fluoro-alpha-isomaltoside. Compound 9 was also obtained by condensation of 1 with 2,3,4-tri-O-benzyl-6-deoxy-6-fluoro-beta-D-glucopyranosyl fluoride (4) in the presence of silver perchlorate and anhydrous stannous chloride. The fully benzylated methyl alpha-glycoside (15) of 6-deoxy-6-fluoro-isomaltotriose, was obtained by condensation of 6 with 4. Hydrogenolysis of 9 and 15 gave the methyl alpha-glycosides of isomaltose and isomaltotriose fluorinated at C-6 of their (nonreducing) D-glucosyl group. Fluoride-ion displacements involving DAST and methyl DAST gave practically identical results, but mixtures arising from reactions involving the latter reagent were lighter-colored and easier to resolve by chromatography. The isolation of methyl alpha-glycosides of 6'-deoxy-6'-fluorogentiobiose and of 6'-O-(6-deoxy-6-fluoro-beta-D-glucopyranosyl) isomaltose is also described.
当在2,4,6 - 三甲基吡啶存在下，用高氯酸银促进2,3,4 - 三 - O - 苄基 - α - D - 吡喃葡萄糖苷甲酯（1）与6 - O - 乙酰基 - 2,3,4 - 三 - O - 苄基 - α - D - 吡喃葡萄糖基氯在乙醚中缩合时，以高立体选择性形成了6 - O - （6 - O - 乙酰基 - 2,3,4 - 三 - O - 苄基 - α - D - 吡喃葡萄糖基） - 2,3,4 - 三 - O - 苄基 - α - D - 吡喃葡萄糖苷甲酯（5）。5进行O - 脱乙酰化，然后用二乙氨基三氟化硫（DAST）或二甲氨基三氟化硫（甲基DAST）处理仅含有未取代的HO - 6'的生成的6，得到6'-脱氧 - 6'-氟 - α - 异麦芽糖苷甲酯的全 - O - 苄基衍生物（9）。化合物9也可通过在高氯酸银和无水氯化亚锡存在下，1与2,3,4 - 三 - O - 苄基 - 6 - 脱氧 - 6 - 氟 - β - D - 吡喃葡萄糖基氟（4）缩合得到。6 - 脱氧 - 6 - 氟异麦芽三糖的全苄基化α - 糖苷甲酯（15）通过6与4缩合得到。9和15的氢解得到在其（非还原）D - 葡萄糖基的C - 6处氟化了的异麦芽糖和异麦芽三糖的α - 糖苷甲酯。涉及DAST和甲基DAST的氟离子取代给出了几乎相同的结果，但涉及后一种试剂的反应产生的混合物颜色较浅，并且更容易通过色谱法分离。还描述了6'-脱氧 - 6'-氟龙胆二糖和6'-O - （6 - 脱氧 - 6 - 氟 - β - D - 吡喃葡萄糖基）异麦芽糖的α - 糖苷甲酯的分离。
