Nucleosides with antiviral and anticancer activity

Abstract

wherein R1-R6 and X have any of the values described herein, as well as pharmaceutical compoustions comprising such compounds and therapeutic methods comprising the administration of such compounds.

1 . (canceled) 
     
     
         2 . A compound of formula: 
       
         
           
           
               
               
           
         
         or a pharmaceutically acceptable salt thereof.