Patent ID: 8586729

Claim:
A method for producing a β-enriched protected decitabine of formula I: wherein each of R 1 is C 1 -C 8 alkyl group or aryl group, each of R 2 and R 3 is independently hydrogen or Si(R 4 ) 3 , and R 4 is independently optionally substituted C 1 -C 8 alkyl group or aryl group, comprising: a) coupling a protected 2-deoxy-ribofuranose of formula II: wherein each of R 1 is as defined above, and R 5 is alkylcarbonyl group, arylcarbonyl group, alkylsulfonyl group, fluoroalkylsulfonyl group or arylsulfonyl group, with a protected 5-azacytosine, of formula III: wherein each of R 4 is as defined above, in the presence of an organic solvent and a catalyst to form a reaction mixture comprising the protected decitabine of formula I; and b) quenching the reaction mixture of step a) with a primary amine to maintain the ratio of β-anomer to α-anomer of the protected decitabine of formula I in the reaction mixture at no less than 1.5:1; wherein the primary amine is soluble in the organic solvent.