| abstract |
The present invention provides processes for preparing intermediates useful in the preparation of gemcitabine and other nucleosides, and processes for preparing gemcitabine therewith. Exemplary intermediates include mixtures of D-erythro and D-threo isomers of 3-(hydroxy)-2,2-difluoro-3-(2,2-dimethyldioxolan-4-yl)-propionic acid salts. Also provided is a process for selectively isolating the D-erythro and D-threo isomers of D-erythro and D-threo isomers of 3-(hydroxy)-2,2-difluoro-3-(2,2-dimethyldioxolan-4-yl)-propionic acid salts, and processes for using such isomers in the preparation of nucleoside analogs such as, e.g., gemcitabine, intermediates thereof, and analogs thereof. |