Construction of Functional Molecules Using Cholic Acid as a Building Block

(1)双环胆碱类化合物的合成及其识别性能本研究的目的是利用胆酸这一廉价易得的甾体化合物作为选择性识别生物重要分子的构筑块来制备新型主体化合物。本论文主要研究了以下三个方面的内容：利用内表面含三个羟基的L刚性分子的特性，制备了具有不同空腔尺寸的双环胆红素。在液(氯)仿-液(水)萃取法中，它们对核糖核苷和糖表现出较好的萃取性。在固-液(氯仿)萃取法中，核糖核苷的结合常数为10^4m~(-1)~(-1)。AZT是一种重要的抗病毒药物，尤其是抗艾滋病药物，它被包含在胆碱类化合物的空腔中，通过~1H-核磁共振滴定对其进行了表征。2)双环胆碱类化合物与相应的三脚类化合物的识别能力比较。如果真的需要环状结构作为潜在的主体分子，我们制备了具有三个胆酸单元的三脚型主体分子，并考察了它们对核苷的识别能力。粗略地说，除了极少数情况外，这些三脚架的识别能力都很差。金属络合物双环胆烷的合成。通过与Ru的络合反应，合成了末端含有三个胆酸单元和联吡啶的新型配体，用于合成双环胆烷。用电喷雾质谱和吸收光谱对其结构进行了表征。

(1) Synthesis of bicyclocholaphanes and their recognition abilities.The aim of this research project is to prepare novel host compounds usings cholic acids, the cheap easily available steroid, as a building block for the selective recognition of biologically important molecules. The following three topics were investigated.By employing its characteristic features, the rigid L-shaped molecule with three hydroxyl groups on its inner surface, bicyclocholaphanes with several cavity sizes were prepared. They showed reasonable extractability toward ribonucleosides and sugars in liquid (chloroform) - liquid (water) extraction. Strong binding constants (10^4M^<-1>) were obtained for ribonucleoside in solid - liquid (chloroform) extraction by them. AZT, an important anti-viral agent especially for AIDS, was included inside the cavities of cholaphanes, which was characterized by ^1H-NMR titration.2) Comparison of recognition abilities of bicyclocholaphanes with the corresponding tripodants.Whether cyclic structures were really necessary as a potential host molecules, the tripodant-type host molecules possessing three cholic acid units attached to cyclotribenzylene (a rigid molecules) and trimesic acid were prepared and their recognition abilities toward nucleosides were examined. Roughly speaking, these tripodants showed poor recognition abilities except few cases. It seems to be these tripodants have too flexible conformations so that they cannot bind guest molecules well.(3) Synthesis of bicyclochopahanes with metal complex formation.The novel ligand possessing three cholic acid units and bipyridyl at the end was prepared for the formation of bicyclocholaphane by complex formation with ruthenium. The complex was characterized by its ESI-MS and absorption spectrum.