Abstract: The instant invention is drawn to a method for manufacturing 2',3'-dideoxy-2',3'-didehydronucleoside compounds by reacting a ribonucleoside derivative wherein the hydroxyl in the 5'-position of the furanose ring of said ribonucleoside is protected by a silyl protective group, with an acid anhydride such as acetic anhydride in the presence of a catalyst such as hydrous zirconium oxide, and then subjecting the reaction product to decarboxylation. The decarboxylation can be effected by heating the reaction product. This method can be performed in a single step, and requires no reagents which are expensive or chemicals which should be handled with care. Hence, it serves to manufacture 2',3'-dideoxy-2',3'-didehydronucleosides easily at low cost.

Abstract: This invention provides a process for producing 3'-deoxy-'-fluorothymidine, which comprises allowing 3'-deoxy-'-fluoro-5'-mesylthymidine (the stating material) to react with an acetylating agent, selected from the group consisting of alkali metal salts of acetic acid, amine salts of acetic acid and ammonium acetate, in an aprotic, ploar solvent to form the 5'-acetyl derivative, and ammonium acetate, in an aprotic, polar solvent to form the 5'-acetyl derivative, and eliminating the 5'-acetyl group from this intermediate, thereby giving the objective 3'-deoxy-'-fluorothymidine.According to the process of this invention described above, the 5'-mesyl derivative can be efficiently acetylated, and 3'-deoxy-'-fluorotymidine can be obtained in a high yield.