Patent ID: 8420354

Claim:
A process for preparing a substantially pure enantiomer of a β-D- or β-L-1,3-dioxolane nucleoside comprising: a) obtaining an esterified 2,2-dialkoxy ethanol of the formula (Ia): or an aldehyde of formula (Ib): wherein: each R 1 is independently alkyl, aryl, heteroaryl, heterocyclic, alkaryl, alkylheteroaryl, alkylheterocyclic, or aralkyl; and R 2 is —C(O)—CH 2 CH 2 CH 3 ; b) reacting the esterified 2,2-dialkoxy ethanol of the formula (Ia) or the aldehyde of formula (Ib) with glycolic acid to obtain a 1,3-dioxolane lactone of the formula (II): c) resolving the 1,3-dioxolane lactone of the formula (II) to obtain a substantially pure D- or L-lactone, with an enzyme selected from the group consisting of Porcine Pancreatic Lipase, Lipase PS, immobilized lipase Pseudomonas , Lipase M, and Actinobacter microbial strains; d) selectively reducing with a reducing agent the substantially pure D- or L-chiral lactone and reacting the reduced lactone with acetic anhydride to obtain a substantially pure D- or L-1,3-dioxolane of the formula (III): wherein L is acetate; e) coupling the substantially pure D- or L-1,3-dioxolane of the formula (III) to a protected purine or pyrimidine base to obtain α:β mixture of substantially pure protected D- or L-1,3-dioxolane nucleosides of the formula (IV): wherein B is a purine or pyrimidine base or its derivative; f) optionally purifying the α:β mixture of substantially pure protected D- or L-1,3-dioxolane nucleosides of the formula (IV) to obtain a substantially pure protected β-D- or β-L-1,3-dioxolane nucleoside; and g) deprotecting the substantially pure protected β-D- or β-L-1,3-dioxolane nucleoside to obtain a substantially pure β-D- or β-L-1,3-dioxolane nucleoside.