| 摘要 |
The present invention relates to more improved process for preparing 2'-deoxy-2',2'-difluoronucleoside and its intermediate. The present invention provide a process for preparing an erythro enantiomer in greater than 98% purity, comprising forming a lactone ring by hydrolyzing ethyl (3RS)-2,2-difluoro-3-hydroxy-3-(2,2-dimethyloxolan-4-yl)propionate is hydrolyzed in the presence of hydrolysis reagents selected from acetic acid or chloroacetic acid, water and a mixture of organic solvents selected from the group comprising acetonilrile, dioxane, tetrahydrofuran or toluene, introducing a substituted benzoyl protecting group at the 3-position and 5-position, and recrys- tallizing said erythro enantiomer. Further, the present invention provides a process for selectively preparing, in greater than 99% purity, a beta-anomer 2'-deoxy-2',2'-difluoronucleoside at the 3'-position and 5'-position that are protected by a substituted benzoyl in a 2:3 alpha/beta anomeric ratio.
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