Studies on Molecular Recognition and Precise Separation Using Cyclodextrin Derivatives

1.对α-、β-或γ-环糊精(CD)的三种羟基进行了选择性甲基化，得到了单甲基化、双甲基化或三甲基化的Cd。合成了七(3-或6-单乙酰、2，3-或3，6-二乙酰和2，3，6-三乙酰)-β-CD。α-和γ-Cd的2，3-位上的羟基也是双乙酰化的。在毛细管区带电泳法(CZE)中，以十二种丹磺酰胺酸为手性选择剂，考察了这些CD二糖对映体的手性分离能力。未修饰的和6-单甲基的β-Ces表现出类似的高对映选择性。在这些情况下，D-对映体总是比对应的L对映体迁移得更快。将β-CD中的2-羟基甲基化后，除了丹磺酰-DL-α-氨基丁酸外，其对映体选择性完全消失。另一方面，β-CD经3-甲基化后仍具有手性拆分能力。与未修饰和6-甲基化的β-CD相反，在3-单甲基化的β-CD存在下，L对映体迁移更快，未修饰的伽马-CD也表现出较高的对映体选择性，2，3，6-三甲基化的α-CD和2，6-二甲基的伽马-CD可以拆分6种丹磺酰氨基酸。乙酰化的β-环糊精衍生物几乎不能拆分它们，但模板基线分离的DL-丙氨基-β-萘胺立体地比丹磺酰胺酸低。用600 MHz NMR.2，6-二甲基β-环糊精和未修饰的γ-环糊精(加入环糊精后复制其质子信号)，以及2，3-二乙酰化和未修饰的环糊精对DL-丙氨基-β-萘胺的手性识别能力进行了研究。

1. Three kinds of hydroxyl groups of alpha-, beta- or gamma-cyclodextrun (CD) were selectively methylated to produce mono-, di-, or trimethylated CDs. Heptakis (3- or 6-monoacetyl, 2,3- or 3,6-diacetyl and 2,3,6-triacetyl)-beta-CDs were synthesized. The hydtoxyl groups of alpha- and gamma-CDs at their 2,3-positions were also diacetylated.2. The chiral separation ability of these CD diribatives as chiral slectors in capillary zone electrophoresis (CZE) was investigated using twelve dansylamino acids. Unmodified and 6-jmonomethylaed beta-CEs exhibite similar high enantioselectiveties. In these cases, the D-enantiomers invariably migrated faster than the crresponding L-enantioers. Methlation of the 2-hydroxyl groups in beta-CD resulted in the complete disappearance of enantioselectivity except for dansyl-DL-alpha-aminobutyric acid. On the other hand, beta-CD still exhibited chiralseparation ability after 3-methylation. Contrary to the cases of unmodified and 6-monmethylated beta-CDs, the L enantiomers migrated faster in the presence of 3-monomethylated beta-CD, Unmodified gamma-CD also exhibited high enantioselectivity, and 2,3,6-trimethylated alpha-CD and 2,6-dimethylated gamma-CD could resolve six dansylamino acid. The acetylated beta-CD derivatives could scarcely resolve them but gave camplate baseline sepatations of DL-alanyl beta-naphthylamide sterically saller than dansylamino acids.3. The chiral recognition ability of some of the CD derivatives were also studied by 600 MHz NMR.2,6-Dimethylated beta-CD and unmodified gamma-(duplication of their proton signals after addition of the CDs), and 2,3-diacetylated and unmodified beta-CDs for DL-alanyl beta-naphthylamide.