Jindrich J, Pitha J, Lindberg B, Seffers P, Harata K
National Institutes of Health, NIA/GRC, Baltimore, MD 21224.
Carbohydr Res. 1995 Jan 3;266(1):75-80. doi: 10.1016/0008-6215(94)00251-a.
Mono-2-O-methyl-, -2-O-ethyl-, and -2-O-allyl-cyclomaltoheptaose were prepared by alkylations of cyclomaltoheptaose in dilute aqueous alkali, and mono-2-O-propylcyclomaltoheptaose was obtained by hydrogenation of the allyl derivative. All the 2-O-alkyl derivatives were less soluble in water than was cyclomaltoheptaose. All formed inclusion complexes with toluene in aqueous solution, but only the methyl ether was less soluble in the water-toluene system than in water. The solubilities of the other ethers in water were enhanced by the addition of toluene. Partial methylation of cyclomaltoheptase with 13C-enriched dimethyl sulfate in dilute aqueous alkali yielded mixtures of products. The substitution patterns were analyzed by GLC-MS of the alditol acetates, prepared by hydrolysis, reduction, and acetylation, and by 13C NMR after complete permethylation with nonenriched reagent. The results showed that methylation at O-2 is a predominant but not an exclusive reaction; as expected, the regioselectivity decreases with increasing degree of methylation.
单 -2-O-甲基、-2-O-乙基和 -2-O-烯丙基 - 环麦芽七糖是通过在稀碱水溶液中对环麦芽七糖进行烷基化反应制备的，单 -2-O-丙基环麦芽七糖是通过烯丙基衍生物的氢化反应得到的。所有 2-O-烷基衍生物在水中的溶解度都比环麦芽七糖小。它们在水溶液中均能与甲苯形成包合物，但只有甲基醚在水 - 甲苯体系中的溶解度比在水中小。加入甲苯后，其他醚类在水中的溶解度增加。在稀碱水溶液中用富含 13C 的硫酸二甲酯对环麦芽七糖进行部分甲基化反应，得到产物混合物。通过对水解、还原和乙酰化后制备的糖醇乙酸酯进行气相色谱 - 质谱分析，以及在用未富集试剂进行完全甲基化后通过 13C 核磁共振分析取代模式。结果表明，在 O-2 位的甲基化是主要反应但不是唯一反应；正如预期的那样，区域选择性随着甲基化程度的增加而降低。
