Preparation of alkyl-substituted 2-deoxy-2-fluoro-d-ribofuranosyl pyrimidines and purines and their derivatives

Abstract

The present invention provides (i) a process for preparing a 2-deoxy-2-fluoro-2-methyl-D-ribonolactone derivative, (ii) conversion of the lactone to nucleosides with potent anti-HCV activity, and their analogues, and (iii) a method to prepare the anti-HCV nucleosides containing the 2-deoxy-2-fluoro-2-C-methyl-β-D-ribofuranosyl nucleosides from a preformed, preferably naturally-occurring, nucleoside.

1 - 18 . (canceled) 
   
   
       19 . A 3,5-di-O-protected-2-deoxy-2-fluoro-2-C-methyl-D-ribono-γ-lactone of the following general formula: 
     
       
         
         
             
             
         
       
       wherein R 3  and R 5  can be independently H, CH 3 , or acyl; 
       alternatively, R 3 ′ and R 5 ′ are linked through —SiR 2 —O—SiR 2 — or —SiR 2 —, wherein R is a lower alkyl such as CH 3 , ethyl, and n-Pr or I-Pr.