2′ Modified oligonucleotides

An oligonucleotide having the formula:

• or a salt thereof, wherein:
• each B independently is a protected or unprotected purine or pyrimidine base in the β-anomeric configuration;
• W3 and W4 are each independently H, PO3−2, a protecting group, or an intermediate moiety in the formation of an internucleotide link which when reacted with the appropriate —OH results in Z;
• n is an integer of 1-200;
• each Z is independently is P(O)O, P(O)S or P(O)N(R)2 provided at least one Z is not P(O)O;
• each R is independently H or alkyl (C1-6);
• each A is OCH3, H, OH, O—Pr wherein Pr is a protecting group, or X—Y wherein:
• X is O;
• and
• Y is substituted or unsubstituted alkyl (C2-20) or substituted or unsubstituted alkenyl (C2-20), wherein the substituents are a halogen, OH, NH2, SH, —O—, —CH2CONH2, —CH2COOCH2CH3, or CH2CONHCH2NH2;
• and at least one A is OCH3.