Patent ID: 6870048

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 which includes the steps of: (a) halogenating an optionally protected L-arabinal of the formula (III): wherein each of R 3 is independently hydrogen, alkyl, acyl or silyl and deprotecting, if necessary, to form the 2-deoxy-2-halo-L-arabinopyranose of the formula (II): wherein each of R 1 and R 2 is independently hydrogen, alkyl, acyl or silyl; (b) converting the 2-deoxy-2-halo-L-arabinopyranose to the 2-deoxy-2-halo-L-arabinofuranose; and (c) coupling the arabinofuranose to a pyrimidine, purine, heterocyclic or heteroaromatic base to form a 2′-deoxy-2′-halo-β-L-arabinofuranosyl nucleoside of the formula (I).