Patent ID: 7585851

Claim:
A 3′-substituted-β-L nucleoside of the formula (I) or its pharmaceutically acceptable salt thereof, wherein R 1 is hydrogen, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, amino acid acyl residue, mono, di, or triphosphate; R 2 is an amino acid acyl residue; X is O; and BASE is selected from the group consisting of 1-thyminyl, 1-cytosinyl, 5-fluoro-1-cytosinyl, 5-methyl-1-cytosinyl, 6-aza-1-pyrimidinyl, 2-mercapto-1-pyrimidinyl, 1-uracilyl, 5-halo-1-uracilyl, C 5 -alkyl-1-pyrimidinyl, 5-iodo-1-pyrimidinyl, 6-iodo-1-pyrimidinyl, 5-(2-bromovinyl)-1-pyrimidinyl, 6-(2-bromovinyl)-1-pyrimidinyl, C 5 -benzyl-1-pyrimidines, C 5 -halo-1-pyrimidinyl, C 5 -vinyl-1-pyrimidinyl, C 5 -acetylenyl pyrimidinyl, C 5 -acyl 1-pyrimidinyl, C 5 -cyano-1-pyrimidinyl, C 5 -nitro-1-pyrimidinyl, C 5 -amino-1-pyrimidinyl, 5-aza-1-cytidinyl, 5-aza-1-uracilyl.