Patent ID: 7291726

Claim:
A process for the preparation of a 2′-deoxy-2′-halo-β-L-arabinofuranosyl nucleoside of the formula (I): wherein X is a halogen; and B is a pyrimidine, purine, heterocyclic or heteroaromatic base; comprising the steps of: (a) halogenating an optionally protected L-arabinose of the formula (IV): wherein each of R 1 , R 2 , R 3 and R 4 is independently hydrogen, alkyl, acyl or silyl by replacing OR 1 with a halogen, to obtain a compound of the formula (V); wherein X 1 is a halogen; (b) reducing the compound of formula (V) to form a compound of formula (III) (c) halogenating the compound of formula (III) to afford an optionally protected 2-deoxy-2-halo-L-arabinopyranose; (d) deprotecting the optionally protected 2-deoxy-2-halo-L-arabinopyranose, if necessary, to form a 2-deoxy-2-halo-L-arabinopyranose; (e) converting the 2-deoxy-2-halo-L-arabinopyranose, with a suitable acid, to a 1-O-alkyl-2-deoxy-2-halo-L-arabinofuranose; (f) halogenating the 1-O-alkyl-2-deoxy-2-halo-L-arabinofuranose with H—X, wherein X is F, Cl, Br, or I, optionally with a suitable acid, to replace the 1-O-alkyl group with a halogen; (g) coupling the arabinofuranose to a protected pyrimidine, purine, heterocyclic or heteroaromatic base; and (h) deprotecting to obtain the 2′-deoxy-2′-halo-β-L-arabinofuranosyl nucleoside.