Oligonucleotides comprising acyclic and abasic nucleosides and analogs

1. An oligonucleotide comprising at least one monomer of formula (V):

wherein the oligonucleotide is a double-stranded siRNA, a single-stranded siRNA, or a hairpin oligonucleotide, and

wherein:

X 1 and X 2 are independently for each occurrence absent, O, S, or NR′;

each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is independently for each occurrence H, halo, OR 13 , N(R′)(R″), straight chain or branched chain alkyl, alkenyl, alkynyl, aryl, ω-amino alkyl, ω-hydroxy alkenyl, or ω-hydroxy alkynyl, each of which can be optionally substituted;

R 11 and R 12 are independently for each occurrence H,

nucleoside, oligonucleotide,

—O-oligonucleotide, —S-oligonucleotide, —S—S-oligonucleotide, —N(R′)—C(Z 6 )-oligonucleotide, —C(Z 6 )—N(R′)-oligonucleotide, —N(R′)—C(Z 6 )Z 6 -oligonucleotide, —Z 6 C(Z 6 )—N(R′)-oligonucleotide, N(R′)C(Z 6 )N(R′)-oligonucleotide

provided that at least one of R 11 and R 12 contains an oligonucleotide;

R 13 is independently for each occurrence H, straight chain or branched chain alkyl, alkenyl, alkynyl, aryl, aralkyl, ω-amino alkyl, or ω-hydroxy alkenyl, each of which can be optionally substituted;

R 14 is independently for each occurrence H, halo, OR 12 , N(R′)(R″), alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, ω-amino alkyl, ω-hydroxy alkyl, or ω-hydroxy alkenyl, each of which can be optionally substituted;

X 3 , X 4 , X 5 , and Z 3 are each independently for each occurrence H, O − , OM, OR 13 , S − , SR 13 , SM, N(R′)(R″), B(R 13 ) 3 , BH 3 − , or Se;

Z 1 and Z 2 are each independently O, S, N(R′), C(R 9 )(R 10 ), C(R 9 )(OR 13 ), C(O), or C(S);

Y 3 , Y 4 , Y 5 , and Z 6 are each independently for each occurrence O or S;

Z 4 is independently for each occurrence O, S, CH 2 , or NR′;

each of R′ and R″ is independently for each occurrence H, alkyl, alkenyl, alkynyl, aryl, ω-amino alkyl, ω-hydroxy alkyl, ω-hydroxy alkenyl, or o-hydroxy alkynyl, each of which can be optionally substituted;

each of m, n, p, q, and r is independently for each occurrence 0-1, provided that m+p+r=2;

t is 0-2; and

M is an organic or inorganic cation,

wherein, in each occurrence, the optionally substituted group is independently selected from the group consisting of halo, hydroxy, oxo, nitro, haloalkyl, alkyl, alkaryl, aryl, aralkyl, alkoxy, aryloxy, amino, acylamino, alkylcarbamoyl, arylcarbamoyl, aminoalkyl, alkoxycarbonyl, carboxy, hydroxyalkyl, alkanesulfonyl, arenesulfonyl, alkanesulfonamido, arenesulfonamido, aralkylsulfonamido, alkylcarbonyl, acyloxy, cyano, and ureido.

2. The oligonucleotide of claim 1 , wherein the monomer is of formula (V′):

3. The oligonucleotide of claim 1 , wherein at least one of R 11 or R 12 is

4. An oligonucleotide comprising at least one monomer of formula (VIII):

wherein the oligonucleotide is a double-stranded siRNA, a single-stranded siRNA, or a hairpin oligonucleotide, and

wherein:

each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is independently for each occurrence H, halo, OR 13 , N(R′)(R″), straight chain or branched chain alkyl, alkenyl, alkynyl, aryl, ω-amino alkyl, ω-hydroxy alkenyl, or ω-hydroxy alkynyl, each of which can be optionally substituted;

R 11 and R 12 are independently for each occurrence H,

nucleoside, oligonucleotide

—O-oligonucleotide, —S-oligonucleotide, —S—S-oligonucleotide, —N(R′)—(C(Z 6 )-oligonucleotide, —C(Z 6 )—N(R′)-oligonucleotide, —N(R′)—C(Z 6 )Z 6 -oligonucleotide, —Z 6 C(Z 6 )—N(R′)-oligonucleotide, N(R′)C(Z 6 )N(R′)-oligonucleotide,

provided that at least one of R 11 and R 12 contains an oligonucleotide;

R 13 is independently for each occurrence H, straight chain or branched chain alkyl, alkenyl, alkynyl, aryl, aralkyl, ω-amino alkyl, or ω-hydroxy alkenyl, each of which can be optionally substituted;

R 14 is independently for each occurrence H, halo, OR 2 , N(R′)(R″), alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, ω-amino alkyl, ω-hydroxy alkyl, or ω-hydroxy alkenyl, each of which can be optionally substituted;

X 3 , X 4 , X 5 , and Z 3 are each independently for each occurrence H, O − , OM, OR 13 , S − , SR 13 , SM, N(R′)(R″), B(R 13 ) 3 , BH 3 − , or Se;

Z 1 and Z 2 are each independently O, S, N(R′), C(R 9 )(R 10 ), C(R 9 )(OR 13 ), C(O), or C(S);

Y 3 , Y 4 , Y 5 , and Z 6 are each independently for each occurrence O or S;

Z 4 is independently for each occurrence O, S, CH 2 , or NR′;

each of R′ and R″ is independently for each occurrence H, alkyl, alkenyl, alkynyl, aryl, ω-amino alkyl, ω-hydroxy alkyl, ω-hydroxy alkenyl, or ω-hydroxy alkynyl, each of which can be optionally substituted;

each of m, n, p, q, and r is independently for each occurrence 0-1, provided that m+p+r=2;

n1 and n2 are each independently 0-49, provided that at least one of n1 and n2 is present, and when one of n1 and n2 is present, the other one is absent;

t is 0-2; and

M is an organic or inorganic cation,

wherein, in each occurrence, the optionally substituted group is independently selected from the group consisting of halo, hydroxy, oxo, nitro, haloalkyl, alkyl, alkaryl, aryl, aralkyl, alkoxy, aryloxy, amino, acylamino, alkylcarbamoyl, arylcarbamoyl, aminoalkyl, alkoxycarbonyl, carboxy, hydroxyalkyl, alkanesulfonyl, arenesulfonyl, alkanesulfonamido, arenesulfonamido, aralkylsulfonamido, alkylcarbonyl, acyloxy, cyano, and ureido.

5. The oligonucleotide of claim 4 , wherein n1 or n2 is 1-20.

6. The oligonucleotide of claim 1 , wherein the monomer is at the 5′-end terminal position of the oligonucleotide.

7. The oligonucleotide of claim 1 , wherein the monomer is at the 3′-end terminal position of the oligonucleotide.

8. The oligonucleotide of claim 1 , wherein the monomer is at an internal position of the oligonucleotide.

9. The oligonucleotide of claim 1 , wherein the monomer is at both the 5′- and 3′-end terminal position of the oligonucleotide.

10. The oligonucleotide of claim 1 , wherein the monomer is present at the 5′-end terminal position and at least one internal position of the oligonucleotide.

11. The oligonucleotide of claim 1 , wherein the monomer is present at the 3′-end terminal position and at least one internal position of the oligonucleotide.

12. The oligonucleotide of claim 1 , wherein the monomer is present at the 5′-end and the 3′-end terminal position and at least one internal position of the oligonucleotide.

13. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises at least one non-phosphodiester internucleoside linkage.

14. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises at least one non-phosphodiester internucleoside linkage selected from the group consisting of phosphorothioate, phosphorodithioate, H-phosphonate, alkyl-phosphonate, phosphoramidate internucleoside linkages, and any combinations thereof.

15. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises at least one nucleobase modification.

16. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises at least one sugar modification.

17. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises at least one ligand conjugate.

18. The oligonucleotide of claim 1 , wherein the oligonucleotide is a double-stranded siRNA comprising a first strand and a second strand.

19. The oligonucleotide of claim 1 , wherein the oligonucleotide is a double-stranded siRNA comprising a first strand and a second strand, and wherein both strands of the double-stranded siRNA independently comprise at least one monomer of formula (V).

20. The oligonucleotide of claim 4 , wherein the oligonucleotide is a double-stranded siRNA comprising a first strand and a second strand, and wherein both strands of the double-stranded siRNA independently comprise at least one monomer of formula (VIII).

21. The oligonucleotide of claim 18 , wherein the first strand is a sense strand.

22. The oligonucleotide of claim 18 , wherein the second strand is an antisense strand.

23. The oligonucleotide of claim 1 , wherein the oligonucleotide is a single-stranded siRNA.

24. The oligonucleotide of claim 1 , wherein the oligonucleotide is a hairpin oligonucleotide.

25. The oligonucleotide of claim 1 , wherein the oligonucleotide comprises:

1-20 first-type regions, each first-type region independently comprising 1-20 contiguous nucleosides wherein each nucleoside of each first-type region comprises a first-type modification;

0-20 second-type regions, each second-type region independently comprising 1-20 contiguous nucleosides wherein each nucleoside of each second-type region comprises a second-type modification; and

0-20 third-type regions, each third-type region independently comprising 1-20 contiguous nucleosides wherein each nucleoside of each third-type region comprises a third-type modification,

wherein the first-type modification, the second-type modification, and the third-type modification are each independently selected from the group consisting of 2′-F, 2′-OCH 3 , 2′-O(CH 2 ) 2 OCH 3 , BNA, F-HNA, 2′-H and 2′-OH.