Patent ID: 7528247

Claim:
A process for the stereoselective preparation of a 2′-deoxy-β-nucleoside of the formula: wherein: R 2 and R 3 are independently hydroxy protecting groups, R 7 and R 8 are independently hydrogen, C 1 -C 4 alkyl, or amino protecting groups, and R 11 is a halogen or —NR 7 R 8 , wherein R 7 and R 8 are as described above; comprising reacting a 2-deoxy-α-arabinofuranosyl derivative of the formula: wherein R 9 is a halogen and R 2 and R 3 are as defined above, with an adenine derivative potassium salt of the formula: wherein: R 7 , R 8 and R 11 are as defined above, in the presence of a substantially anhydrous solvent, wherein the substantially anhydrous solvent is a mixture of t-amyl alcohol, acetonitrile and dichloroethane or a mixture of t-amyl alcohol, acetonitrile and dichloromethane, wherein the ratio of solvents in said solvent mixture of t-amyl alcohol, acetonitrile and dichloroethane is about 2:1:1 by volume, respectively, or the ratio of solvents in said solvent mixture of t-amyl alcohol, acetonitrile and dichloromethane is about 2:1:1 by volume, respectively, and wherein said 2′-deoxy-β-nucleoside is produced in said substantially anhydrous solvent in a molar ratio of greater than 10:1 relative to the 2′-deoxy-α-nucleoside anomer represented by the formula: