Patent ID: 8536378

Claim:
A compound according to the formula wherein R 3 is selected from the group consisting of OR, halo, SeR, SR, SOR, SO 2 R, aryl, NHR, NR 2 , NHCOR, where R is lower alkyl of 1-15 C; R 4 is selected from the group consisting of hydrogen, alkyl (C1 to C20), cyclic alkyl (C3 to C15) aromatic ring (C4 to C6), hydroxyl, alkyl carbonate, carbamate, ester, ether, thiol, amine, phosphine, phosphate, phosphoramide, phosphoramidite, phosphoramidate, phosphite, phosphonate, sulfate, sulfonate, sulfonamide, sulfone, sulfite, amide, guanidine, and urea; and R 5 is selected from the group consisting of hydrogen, alkyl (C1 to C20), cyclic alkyl (C3 to C15) aromatic ring (C4 to C6), hydroxyl, alkyl carbonate, carbamate, ester, ether, thiol, amine, phosphine, phosphate, phosphoramide, phosphoramidite, phosphoramidate, phosphite, phosphonate, sulfate, sulfonate, sulfonamide, sulfone, sulfite, amide, guanidine, and urea.