ACYCLIC AND STEREOCONTROLLED SYNTHESIS OF THIOSUGARS AND PREPARATION OF PSEUDO-NUCLEOSIDE HAVING THE THIOSUGAR MOIETY

Chemical modification of the sugar moiety in nucleoside is one of the promising way to find a new chemotherapeutic agent. Nucleoside possess ing a heterocyclic or carbocyclic ring instead of 2-deoxyribose bose o r ribose is so called pseudo nucleoside. Since HIV (human immunodefici ency virus) has appeared to cause the serious disease in the human lif e, such nucleosides have received considerable attentions as a new ant i-viral medicine. 4'-Thio-nucleoside in which furanose ring oxygen ato m is replaced by a sulfur atom, is of our interest and this review des cribes the synthese of 2'-deoxy-4'-thioribonucleosides. Specific featu res in this article include (i) preparation of 2-mercapto-1,3-diols by acyclic stereocontrol, (ii) synthesis of 2-deoxy-4-thioribose, (iii) glycosidation reaction of thiosugar, and (iv) synthesis and biological activity of 2'-deoxy-4'-thio pyrimidine nucleosides.