Process for the purification and isolation of 2-deoxy-2,2-difluor-nucleosides

摘要

A process to purify and isolate a beta-anomer enriched nucleoside comprising: a) providing a mixture containing R'' and a beta-anomer enriched nucleoside of the formula CHEM wherein each X is independently selected from hydroxy protecting groups and R' is a nucleobase of the formula CHEM where W is an amino protecting group; and R'' is a nucleobase of the formula CHEM where W' is an amino protecting group or hydrogen; in a high boiling solvent; b) diluting the mixture with an organic solvent from the group consisting of ethers, esters and nitriles; c) adding the diluted reaction mixture to aqueous acid; and d) holding the acid mixture so prepared at a temperature from 70 DEG C to 100 DEG C until the product of formula IB, where W is now W', has precipitated.