Preparation of 2'-fluoro-2'-alkyl-substituted or other optionally substituted ribofuranosyl pyrimidines and purines and their derivatives

Abstract

The present invention provides (i) processes for preparing a 2′-deoxy-2′-fluoro-2′-methyl-D-ribonolactone derivatives, (ii) conversion of intermediate lactones to nucleosides with potent anti-HCV activity, and their analogues, and (iii) methods to prepare the anti-HCV nucleosides containing the 2′-deoxy-2′-fluoro-2′-C-methyl-B-D-ribofuranosyl nucleosides from a preformed, preferably naturally-occurring, nucleoside.

1 - 9 . (canceled) 
     
     
         10 . A compound of formulae IIIa, IIIb or IIIc 
       
         
           
           
               
               
           
         
       
       wherein
 each R 1  i.s independently lower alkyl (C 1 -C 6 ), optionally substituted phenyl, or optionally substituted benzyl; 
 R 2  and R 3  are independently hydrogen, lower alkyl (C 1 -C 6 ), hydroxymethyl, methoxymethyl, halomethyl, optionally substituted ethenvi, optionally substituted ethynyl, or optionally substituted allyl; and 
 R 4  is independently hydrogen, aryl, arylalkyl, and lower alkyl (C 1 -C 10 ). 
 
     
     
         11 . A compound of  claim 10 , 
       wherein
 each R 1  is lower alkyl (C 1 -C 6 ); 
 R 2  and R 3  are independently hydrogen, or lower alkyl (C 1 -C 6 ); and 
 R 4  is lower alkyl (C 1 -C 10 ). 
 
     
     
         12 . The compound of  claim 10 , having the formula