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

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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.