Antiviral compounds

1. A compound of Formula (I):

or a pharmaceutically acceptable salt thereof, wherein:

Base is

R 1 and R 2 are each independently H or —C(O)R 1A , wherein R 1A is C 1-6 alkyl;

R 3 is —N(H)R 3A ;

R 3A is H, —CH 2 OP(O)(OH) 2 , or —C(O)R 3D , wherein

R 3D is C 6-12 aryl or C 1-6 alkyl optionally substituted with a C 3-6 cycloalkyl;

R 4A is O;

R 4B and R 4C are each independently:

(A) —OH;

(B) —OR 4B1 , wherein R 4B1 is C 6-12 aryl;

(C)

 wherein

subscript m is 0, 1, 2, 3, 4, or 5; and

each R 4D is independently C 1-6 alkyl;

(D)

 wherein

R 4E1 and R 4E2 are each independently H or C 1-6 alkyl;

R 4F1 and R 4F2 together are oxo;

R 4G is C 1-8 alkyl optionally substituted with 1 to 3 R 4G1 , C 3-8 cycloalkyl, or a 3 to 8 membered heterocyclyl having 1 to 3 heteroatoms selected from N, O and S, optionally substituted with 1 to 3 R 4G3 ;

each R 4G1 is independently —OH, C 1-6 alkoxy, —(CH 2 OCH 2 ) 1-5 —CH 3 , C 1-3 haloalkyl, or C 3-8 cycloalkyl optionally substituted with 1 to 3 R 4G9 ;

each R 4G3 and R 4G9 is independently C 1-6 alkyl; or

(E) —(OP(O)(OH)) 1-2 —OH; and

R 5A is C 1-6 alkyl substituted with —OP(O)(OH) 2 .

2. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 and R 2 are each H.

3. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 and R 2 are each —C(O)R 1A ; and

R 1A is methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or t-butyl.

4. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 1 and R 2 are each —C(O)R 1A ; and

R 1A is methyl, ethyl, or iso-propyl.

5. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the formula:

wherein

R 3 is —N(H)R 3A ;

R 3A is H or —C(O)R 3D ; and

R 3D is phenyl or C 1-3 alkyl optionally substituted with a C 3-6 cycloalkyl.

6. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 3 is —NH 2 .

7. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 4B and R 4C are each independently:

(A) —OH;

(B) —OR 4B1 , wherein R 4B1 is naphthyl;

 (C), wherein

subscript m is 0 or 1; and

R 4D is C 1-6 alkyl;

(D)

 wherein

R 4E1 is C 1-3 alkyl;

R 4E2 is H;

R 4F1 and R 4F2 together are oxo;

R 4G is C 1-8 alkyl optionally substituted with 1 R 4G1 , C 4-6 cycloalkyl, or a 4 to 6 membered heterocyclyl having 1 heteroatom selected from N and O, optionally substituted with 1 R 4G3 ;

each R 4G1 is independently —OH, C 1-4 alkoxy, —(CH 2 OCH 2 ) 1-2 -CH 3 , C 1-3 haloalkyl, or C 3-6 cycloalkyl optionally substituted with 1 R 4G9 ;

each R 4G3 and R 4G9 is independently C 1-3 alkyl; or

(E) —(OP(O)(OH)) 1-2 —OH.

8. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 4B is:

(B) —OR 4B1 , wherein R 4B1 is naphthyl; or

(C)

 wherein

subscript m is 0 or 1; and

R 4D is t-butyl; or

(E) —(OP(O)(OH)) 1-2 —OH.

9. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 4C is:

(A) —OH; or

(D)

 wherein

R 4E1 is methyl;

R 4E2 is H;

R 4F1 and R 4F2 together are oxo; and

R 4G is

methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexane, 2,2-dimethyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, or 2-n-propyl-pentyl, each optionally substituted with OH, methoxy, ethoxy, propoxy, butoxy, CF 3 , Me(CH 2 OCH 2 ) 2 —, cyclopropyl or 1-methylcyclopropyl,

cyclobutyl, cyclopentyl, or cyclohexyl,

pyrrolidinyl, oxetanyl, or tetrahydropyranyl, each optionally substituted with methyl, ethyl, n-propyl or iso-propyl.

10. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 5A is —CH 2 OP(O)(OH) 2 .

11. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ib):

wherein

R 3A is H; and

R 5A is —CH 2 OP(O)(OH) 2 .

12. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Id):

13. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ie):

14. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (If):

15. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ig):

16. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ih):

17. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ij):

18. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Ik):

19. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the Formula (Im):

20. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 4C is:

21. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 4C is:

22. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 4G is

methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexane, 2,2-dimethyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, or 2-n-propyl-pentyl, each optionally substituted with OH, methoxy, ethoxy, propoxy, butoxy, CF 3 , Me(CH 2 OCH 2 ) 2 —, cyclopropyl or 1-methylcyclopropyl,

cyclobutyl, cyclopentyl, or cyclohexyl,

pyrrolidinyl, oxetanyl, or tetrahydropyranyl, each optionally substituted with methyl, ethyl, n-propyl or iso-propyl.

23. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 4G is

methyl optionally substituted with Me(CH 2 OCH 2 ) 2 —, cyclopropyl or 1-methylcyclopropyl,

ethyl optionally substituted with butoxy,

n-propyl optionally substituted with methoxy,

iso-propyl, n-butyl,

iso-butyl optionally substituted with OH, methoxy or CF 3 ,

n-pentyl, neopentyl, n-hexane, 2,2-dimethyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, 2-n-propyl-pentyl,

cyclobutyl, cyclohexyl,

N-methyl-pyrrolidinyl, oxetanyl, or tetrahydropyranyl.

24. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 1 and R 2 are both H or —C(O)R 1A , wherein R 1A is methyl, ethyl or iso-propyl;

R 3 is —NH 2 ;

R 4B is:

OPh; and

R 4C is:

 wherein

R 4G is

methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexane, 2,2-dimethyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, or 2-n-propyl-pentyl, each optionally substituted with OH, methoxy, ethoxy, propoxy, butoxy, CF 3 , Me(CH 2 OCH 2 ) 2 —, cyclopropyl or 1-methylcyclopropyl,

cyclobutyl, cyclopentyl, or cyclohexyl,

pyrrolidinyl, oxetanyl, or tetrahydropyranyl, each optionally substituted with methyl, ethyl, n-propyl or iso-propyl.

25. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having Formula (In):

wherein

R 1 and R 2 are both H or —C(O)R 1A , wherein R 1A is methyl, ethyl or iso-propyl; and

R 4G is

methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexane, 2,2-dimethyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, or 2-n-propyl-pentyl, each optionally substituted with OH, methoxy, ethoxy, propoxy, butoxy, CF 3 , Me(CH 2 OCH 2 ) 2 —, cyclopropyl or 1-methylcyclopropyl,

cyclobutyl, cyclopentyl, or cyclohexyl,

pyrrolidinyl, oxetanyl, or tetrahydropyranyl, each optionally substituted with methyl, ethyl, n-propyl or iso-propyl.

26. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, selected from the group consisting of

27. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

28. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

29. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

30. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

31. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

32. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound is:

33. A pharmaceutical formulation comprising a pharmaceutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.