PROCESS FOR PREPARING GEMCITABINE AND ASSOCIATED INTERMEDIATES

摘要

Provided is a process for preparing gemcitabine and intermediates useful in the production of gemcitabine. Exemplary intermediates include mixtures of D-erythro and D-threo diastereomers of ethyl 3-(N-carbamoyloxy)-2,2-difluoro-3-(2,2-dimethyldioxolan-4-yl)propionates, from which a preferred isomer can be separated, e.g., by selective crystallization, in accordance with the invention. Also provided are novel alkyl (D-erythro)-3-hydroxy-2,2-difluoro-3-(2,2-dimethyldioxolan-4-yl)propionate intermediates, and novel ribo lactones, which can be used for producing gemcitabine.