Precise Synthesis of C-Nucleosides and Relation ship between their Structures and Biological Activity

从生物活性的角度，特别是在抗病毒药物方面，C-核苷类展多霉素和氮杂糖类诺吉霉素已被认为是天然存在的潜在化合物。作为新型DNA亚基合成和鉴定计划的一部分，我们打算合成C-氮杂核苷和C-氮杂脱氧核苷等核苷，它们的结构骨架类似于上述两个化合物：即在糖的异构化位置和碱基之间具有C-C键的核苷，并进一步用氮原子取代内环核糖或脱氧核糖环氧。据我们所知，三个已知的C-氮杂核苷的合成都需要不到的起始原料或包含许多困难的合成步骤。因此，我们建立了一种合成克量C-氮杂核苷的通用方法，即X-射线分析法合成C-氮杂环核苷。作为本研究的延伸，我们首次合成了含有尿嘧啶、氮杂假尿苷等天然碱基的C-氮杂氧基核苷和C-氮杂芳基核苷，并进一步研究了它们的性质和生物活性。

In the viewpoint of biological activity, especially such as antiviral drugs, the C-nucleoside like showdomycin and the azasugar like nojirimycin have been known as naturally occurring and potential compounds. As a part of our program for synthesis and evaluation of a new type of DNA subunits, we intended to synthesize the nucleosides such as C-azanucleosides and C-azadeoxy-nucleosides, which have the structual skeletons similar to two compounds mentioned above : That is, the nucleosides which have a C-C bond between sugar's anomeric position and base moiety, and further, the endocyclic ribosyl or deoxyribosyl ring oxygen is replaced with nitrogen atom. To our best knowledge, the syntheses of three known C-azanucleosides have required unavailable starting materials or contained many difficult synthetic steps. Therefore, we developed a general method for the synthesis of gram quantities of C-azanucleosides, which was C-azalyxonucleosides by X-ray analysis. As the extention of this investigation, we reported the first synthesis of both C-azadeoxylyxonucleosides and C-azalyxonucleosides bearing a natural type of base such as uracil, azapseudouridine and further, their properties and biological activities.