Nucleosides and oligonucleotides containing boron clusters

An oligonucleotide that contains at least one carboranyl-containing base of the formula:

• 7
• wherein:
• C is a carboranyl group such as B10H10C2R4, wherein R4 is —H, —OH, —CH2O H, —CH2X (wherein X is halogen) or —B9C2H(11 or 12) (a nido-carborane anion);
• R5 is lower alkyl;
• G is N or CH;
• M is O or S;
• and
• z is O to 5.

A compound selected from the group consisting of:

• 8
• wherein:
• R1 is alkyl, haloalkyl, alkenyl, alkoxyalkyl, aryl, heteroaryl, trifluoromethyl, alkylaryl, arylalkyl, or halogen;
• R2 is hydrogen, alkyl, acyl (including acetyl);
• sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl;
• a mono-, di- or triphosphate ester;
• trityl or monomethoxytrityl;
• benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given above;
• silyl, including trialkylsilyl (e.g. dimethyl-t-butylsilyl) or diphenylmethylsilyl;
• lipid;
• peptide;
• or cholesterol;
• R3 is hydroxyl, hydrogen, halogen, —CN, —N3, lower alkyl, amino, alkylamino, dialkylamino, alkoxy;
• and wherein the R3 group can be in the ribosyl (“down” with respect to the sugar moiety when orienting the ring such that the oxygen is in the back) or the arabinosyl (“up”) conformation;
• B represents the boron moiety of a carboranyl group, and specifically includes anionic o-nido-7,8-C2B9H(11 or 12) and neutral o-closo-1,2-C2B10H12;
• W is O, S, or Se;
• X is O, S(O), S(O)2, CH2, CHOH, CHN3 or NH;
• Y is OH, SH, SeH, or halogen, and in particular, fluorine;
• n is 1-5;
• and
• m is 0 or 1.