Dinucleotides

A dinucleotide of Formula (I) or Formula (II), or a salt thereof, as shown below:

• wherein:
• C3 and C4 are the carbon atoms at the 3′ and 4′ positions of their respective 5-membered rings;
• Q1 and Q2 are independently selected from CRpRq, O, S or NRs, wherein Rp and Rq are each independently selected from H, (1-4C)alkyl or halo and R5 is selected from hydrogen or (1-4C)alkyl;
• B and B′ are each independently:
• a) a nucleobase;
• RP1 is a protecting group;
• one of X1 and X2 is (CRaRb)x, wherein x is selected from 1 or 2 and the other is CRaRb, O, NRc or S, wherein Ra and Rb are independently selected from hydrogen, (1-2C)alkyl, hydroxy, amino, halo or mercapto, and Rc is selected from hydrogen or a (1-6C)alkyl;
• or one of X1 and X2 is O and the other is NRc;
• bond a is either absent or a single bond;
• one of X3 and X4 is (CRdRc)y, wherein y is selected from 1 or 2 and the other is CRdRe, O, NRf or S, wherein Rd and Re are independently selected from hydrogen, (1-2C)alkyl, hydroxy, amino, halo or mercapto, and Rf is selected from hydrogen or a (1-6C)alkyl;
• or
• one of X3 and X4 is O and the other is NRf;
• or
• one of X3 and X4 is H and the other is selected from H, OH, NH2, OCH3 or F;
• Rz is a solid support or group of formula A1 or A2 shown below:
• with the proviso that A1 or A2 is not present when X3 is CRdRe, and Rd and Re is amino, hydroxyl, or mercapto,
• wherein:
• denotes the point of attachment;
• W1 is selected from O, S or (1-4C)alkyl;
• RP2 is a protecting group;
• Z+ is a positively charged counter ion;
• R1 and R2 are independently selected from hydrogen or (1-6C)alkyl, wherein said alkyl is optionally substituted with one or more substituents selected from halo, nitro, cyano or (1-2C)haloalkyl, with the proviso that the halo substituent is not present on the alpha carbon atom;
• or
• R1 and R2 are linked, such that, together with the nitrogen to which they attached they form a pyrrolidin-1-yl ring which is optionally substituted by one or more substituents selected from (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy, (1-4C)alkylamino, cyano, or nitro;
• and
• L is a triazole phosphodiester mimic, optionally of Formula A or Formula B:
• wherein:
• denotes the point of attachment to C3;
• denotes the point of attachment to C4;
• R2, R3, R4, R5, R6, R7, R8 and R9 are each independently selected from hydrogen or (1-4C)alkyl, wherein each (1-4C)alkyl is optionally substituted with one or more NH2, OH or SH;
• V and Y are independently selected from O, S or NRx, wherein Rx is selected from hydrogen or (1-4C)alkyl;
• m, n, r and s are integers independently selected from 0 to 2;
• and
• p and q are integers independently selected from 0 to 1;
• with the proviso that:
• i) the sum of integers m, n, p, q, r and s is either 0, 1, 2, 3, 4, 5 or 6;
• and
• ii) when W1 is a (1-4C)alkyl, RP2 is absent;
• iii) bond a is only absent when one of X3 and X4 is H and the other is selected from H, OH, NH2, OCH3 or F.