Modified iRNA agents

An iRNA agent comprising a first strand and a second strand, wherein at least two subunits having a formula (I) are incorporated into at least one of said strands:

• wherein:
• X is N(CO)R7, NR7 or CH2;
• Y is NR8, O, S, CR9R10, or absent;
• Z is CR11R12 or absent;
• each of R1, R2, R3, R4, R9, and R10 is, independently, H, ORa, ORb, (CH2)nORa, or (CH2)nORb, provided that at least one of R1, R2, R3, R4, R9, and R10 is ORa or ORb and that at least one of R1, R2, R3, R4, R9, and R10 is (CH2)nORa, or (CH2)nORb;
• each of R5, R6, R11, and R12 is, independently, H, C1-C6 alkyl optionally substituted with 1-3 R13, or C(O)NHR7;
• or R5 and R11 together are C3-C8 cycloalkyl optionally substituted with R14;
• R7 is Rd;
• or C1-C20 alkyl substituted with NRcRd or NHC(O)Rd;
• R8 is C1-C6 alkyl;
• R13 is hydroxy, C1-C4 alkoxy, or halo;
• R14 is NRcR7;
• Ra is H or
• Rb is H or
• wherein the Strand in each occurrence is independently the first strand or second strand of the iRNA agent;
• each of A and C is, independently, O or S;
• and
• B is OH, O−, or
• Rc is H or C1-C6 alkyl;
• Rd is H or a ligand;
• and
• n is 1-4.