新型手性咪唑鎓环番的合成及对氨基酸的对映选择性识别

Design and Synthesis of Novel Chiral Imidazolium Cyclophanes and Their Enantioselective Recognition for α-Amino Acids and Their Derivatives

以L-氨基酸为手性源，合成了一系列新型手性咪唑鎓环番，并进行了结构表征．在碱性条件下，L-氨基酸和乙二醛、甲醛缩合生成了（S）-2-（1-咪唑）羧酸钠，转化为甲酯后与乙二胺进行胺解反应制得开链手性咪唑二酰胺，然后与二溴化合物在高稀淡技术和无水条件下进行季铵化关环反应，再进行阴离子交换制得目标分子（4—6）．以手性咪唑鎓环番为主体分子，研究了对氨基酸及其衍生物的对映选择性识别作用．

A series of novel chiral imidazolium cyclophanes were synthesized from natural amino acids. （S）-2-（ 1-Imidazolyl） alkanoates （2） were prepared by cyclization and esterification. In the presence of DMAP and Et3N. Alkanoates（2） reacted with ethylenediamine to yield compounds 3 with satisfactory yields. Compounds 3 reacted with 2,6-bis（bromomethyl） - 4-chlorphenol, 1,3-bis（bromomethyl） benzene or 2,6-bis（ bromomethyl） pyridine to afford dibromide salts under high dilution and anhydrous condition. Finally, the hexafluorophosphates （4-6） were obtained by treating the corresponding dibromide salts with a saturated aqueous solution of NH4 PF6. The structures of the target compounds were confirmed by IR, ^1 H NMR, MS, HRMS, and elemental analysis. These compounds featured large cavities and multipoint binding sites. UV spectroscopic titration experiments showed these chiral imidazolium cyclophanes exhibited good enantioselective recognition toward L- and D-amino acids and their derivatives.