Patent ID: 7319148

Claim:
A compound of the formula: wherein: R1 is H, a phosphate group, a diphosphate group, a triphosphate group, or DMT; R2 and R2′ are independently selected from H, OH, a phosphoramidite, H-phosphonate, F, Br, Cl, I, N 3 , and a linear or branched alkyl group consisting of 1 to 6 carbon atoms; R3 and R3′ are independently selected from H, OH, a halogen (F, Br, Cl, I), a linear or branched alkyl group consisting of 1 to 6 carbon atoms, and an O—R5 group, wherein R5 is a linear or branched alkyl group consisting of 1 to 6 carbon atoms; R4 is a substituted heterocycle of the formula: wherein: E is a spacer arm of 0 to 20 saturated or unsaturated carbon atoms, wherein from 1 to 20 of the carbon atoms are optionally heteroatoms and/or are optionally substituted; wherein: Y1 is NH 2 (designated by the synthon X0), wherein Z1 and Z2 are independently selected from hydrogen, a thiol, an alkyl, a carbonyl, an amine, an alcohol, an aryl, fluorescamine and fluorescein.