Patent ID: 7390791

Claim:
A diastereomerically enriched compound having the structure (3) which contains less than 40% by weight of the diastereomer (4) wherein R 1 is an oxyester which is hydrolyzable in vivo, or hydroxyl; B is a heterocyclic base; R 2 is hydroxyl, or the residue of an amino acid bonded to the P atom through an amino group of the amino acid and having each carboxy substituent of the amino acid optionally esterified, but not both of R 1 and R 2 are hydroxyl; E is —(CH 2 ) 2 —, —CH(CH 3 )CH 2 —, —CH(CH 2 F)CH 2 —, —CH(CH 2 OH)CH 2 —, —CH(CH═CH 2 )CH 2 —, —CH(C≡CH)CH 2 —, —CH(CH 2 N 3 )CH 2 —, —CH(R 6 )OCH(R 6 )—, —CH(R 9 )CH 2 O— or —CH(R 8 )O—, wherein the right hand bond is linked to the heterocyclic base; the broken line represents an optional double bond; R 4 and R 5 are independently hydrogen, hydroxy, halo, amino or a substituent having 1-5 carbon atoms selected from acyloxy, alkyoxy, alkylthio, alkylamino and dialkylamino; R 6 and R 6′ are independently H, C 1 -C 6 alkyl, C 1 -C 6 hydroxyalkyl, or C 2 -C 7 alkanoyl; R 7 is independently H, C 1 -C 6 alkyl, or are taken together to form —O— or —CH 2 —; R 8 is H, C 1 -C 6 alkyl, C 1 -C 6 hydroxyalkyl or C 1 -C 6 haloalkyl; and R 9 is H, hydroxymethyl or acyloxymethyl; and their salts, free base, and solvates.