The present invention relates to novel compounds according to the general Formulae (I, II, III, IV or V) wherein B is nucleoside base according to the structure Formula (VI) R is H, F, Cl, Br, I, C 1 -C 4 alkyl (preferably CH 3 ), -C‰¡N, -C‰¡C-R a , Formula (VII) X is H, C 1 -C 4 alkyl (preferably CH 3 ), F,Cl,Br or 1 Z is 0 or CH 2 with the proviso that Z is CH 2 and not O when the compound is according to general formula II, R 3 is -C‰¡C-H and R 2 is H or a phosphate, diphosphate, triphosphate or phosphotriester group R 1 is H, an acyl group, a C 1 -C 20 alkyl or an ether group R2 is H, an acyl group, a CI-C20 alkyl or ether group, a phosphate, diphosphate, triphosphate, phosphodiester group or a Formula (VIII) or Formula (IX) group Nu is a radical of a biologically active antiviral compound such that an amino group or hydroxyl group from said biologically active antiviral compound forms a phosphate, phosphoramidate, carbonate or urethane group with the adjacent moiety R8 is H, or a C1-C20 alkyl or ether group, preferably a C1-C12 alkyl group k is 0-12, preferably, 0-2 R3 is selected from a C1-C4 alkyl (preferably CH3), -(CH2)n-C=C-Ra, Formula (X) or Formula (XI) R3a and R3b are independently selected from H, F, C1, Br or I R4 and R5 are independently selected from H, F, Cl, Br, I, OH, C1-C4 alkyl (preferably CH3),-(CH2)n-C‰¡C-Ra, Formula (XII) or Formula (XIII) with the proviso that R4 and R5 are not both H Ra is H,F,Cl,Br,I or -C1-C4 alkyl, preferably H or CH3 Y is H, F, C1, Br, I or -C1-C4 alkyl, preferably H or CH3 and n is 0,1,2,3,4 or 5, preferably 0, 1 or 2 and their anomers, pharmaceutically acceptable salts, solvates or polymorphs thereof.
