Neuroactive steroids, compositions, and uses thereof

1. A compound of Formula (Ib):

or a pharmaceutically acceptable salt thereof;

wherein:

Ring A is an optionally substituted 5-membered or 6-membered monocyclic heterocyclyl or an optionally substituted 5-membered or 6-membered monocyclic heteroaryl, wherein the heterocyclyl or heteroaryl of ring A comprises 1, 2, 3, or 4 nitrogen atoms and wherein the heterocyclyl or heteroaryl of ring A is linked through a nitrogen atom;

L is —C(R 3 )(R 3 )—;

R 1 is unsubstituted C 1-6 alkyl;

R 2 is unsubstituted C 1-6 alkyl or C 1-6 haloalkyl;

Each R 3 is hydrogen;

R 5 is absent or hydrogen;

is a single or double bond, wherein when one of is a double bond, the other is a single bond; and when one of the is a double bond, R 5 is absent.

2. The compound of claim 1 , wherein each is a single bond and R 5 is hydrogen.

3. The compound of claim 2 , wherein R 1 is methyl, ethyl, or isopropyl, each of which is unsubstituted.

4. The compound of claim 3 , wherein R 1 is unsubstituted methyl or unsubstituted ethyl.

5. The compound of claim 1 , wherein R 2 is unsubstituted C 1-6 alkyl.

6. The compound of claim 1 , wherein R 2 is methyl or —CF 3 .

7. The compound of claim 1 , wherein the compound of Formula (Ib) is a compound of Formula (Ib-1):

or a pharmaceutically acceptable salt thereof.

8. The compound of claim 1 , wherein the compound of Formula (Ib) is a compound of Formula (Ib-2):

or a pharmaceutically acceptable salt thereof.

9. The compound of claim 1 , wherein ring A is an optionally substituted 5-membered or 6-membered monocyclic heteroaryl, wherein the heteroaryl of ring A comprises 2, 3, or 4 nitrogen atoms and wherein the heteroaryl of ring A is linked through a nitrogen atom.

10. The compound of claim 1 , wherein the compound of Formula (Ib) is a compound of Formula (Ib-3) or a compound of Formula (Ib-4):

or a pharmaceutically acceptable salt thereof,

wherein

R 4 is cyano, nitro, hydroxy, halo, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, —C(O)R a , —C(O)N(R b )(R c ), —C(O)OR a , —N(R b )(R c ), —OC(O)N(R b )(R c ), —OC(O)OR a , —OC(O)R a , —S(O) 0-2 R a , —S(O) 0-2 OR a , or —S(O) 0-2 N(R b )(R c );

Each R a is independently hydrogen or C 1-6 alkyl;

Each R b and R c is independently hydrogen, C 1-6 alkyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, or

R b and R c , together with the nitrogen atom to which they are bound to form a ring; and

n is 0, 1, 2, or 3.

11. The compound of claim 10 , wherein n is 0, and ring A is

12. The compound of claim 11 , wherein n is 0, and ring A is

13. The compound of claim 10 , wherein n is 1 or 2, and each R 4 is independently cyano, halo, C 1-6 alkyl, C 1-6 alkoxy, —C(O)R a , or —S(O) 0-2 R a .

14. The compound of claim 13 , wherein n is 1, and R 4 is —C(O)CH 3 , —S(O) 2 CH 3 , cyano, halo, or C 1-6 alkyl.

15. The compound of claim 10 , wherein the compound of Formula (Ib) is a compound of Formula (Ib-3):

or a pharmaceutically acceptable salt thereof.

16. The compound of claim 15 , wherein n is 0, and ring A is

17. The compound of claim 16 , wherein n is 0, and ring A is

18. The compound of claim 15 , wherein n is 1 or 2, and each R 4 is independently cyano, halo, C 1-6 alkyl, C 1-6 alkoxy, —C(O)R a , or —S(O) 0-2 R a .

19. The compound of claim 18 , wherein n is 1, and R 4 is —C(O)CH 3 , —S(O) 2 CH 3 , cyano, halo, or C 1-6 alkyl.

20. The compound of claim 10 , wherein the compound of Formula (Ib) is a compound of Formula (Ib-4):

or a pharmaceutically acceptable salt thereof.

21. The compound of claim 20 , wherein n is 0, and ring A is

22. The compound of claim 21 , wherein n is 0, and ring A is

23. The compound of claim 20 , wherein n is 1 or 2, and each R 4 is independently cyano, halo, C 1-6 alkyl, C 1-6 alkoxy, —C(O)R a , or —S(O) 0-2 R a .

24. The compound of claim 23 , wherein n is 1, and R 4 is —C(O)CH 3 , —S(O) 2 CH 3 , cyano, halo, or C 1-6 alkyl.

25. A compound selected from

or a pharmaceutically acceptable salt thereof.

26. A pharmaceutical composition comprising a compound according to claim 1 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient.

27. A method of (a) treating depression, insomnia, seizure, epilepsy, tremor or generalized anxiety disorder or (b) inducing sedation or anesthesia in a human subject in need thereof, comprising administering to the human subject a therapeutically effective amount of a compound or pharmaceutically acceptable salt according to claim 1 .

28. The method of claim 27 , wherein the depression is postnatal depression.

29. The method of claim 27 , wherein the compound or pharmaceutically acceptable salt thereof is administered orally.

30. The method of claim 27 , wherein the compound or pharmaceutically acceptable salt thereof is administered intramuscularly.