Patent ID: RE42015

Claim:
A compound of the formula: or a pharmaceutically acceptable salt thereof, wherein i) R 1 is chosen from hydrogen and halogen; ii) R 2 is chosen from alkyl, alkenyl, alkynyl, cycloalkyl, aminoalkyl, hydroxyalkyl, haloalkyl, thioalkyl, aryl, heteroaryl, and C 6 H 4 R 6 where R 6 is chosen from halogen, CN, CF 3 , N 3 , NO 2 , alkyl, haloalkyl, aminoalkyl, alkoxy, thioalkyl, alkenyl, alkynyl, and aryl; iii) R 3 is chosen from halogen, CN, CF 3 , N 3 , NO 2 , alkyl, alkenyl, and alkynyl; iv) R 3′ is chosen from H, halogen , methyl , or ethyl; and v) R 4 is chosen from H, phosphate, carbonyl substituted with alkyl, alkenyl, alkynyl, aryl, sulfonate ester, a lipid, an amino acid, a peptide, or cholesterol.