Esters of 4, 9-dihydroxy-naphtho [2, 3-b] furans for disease therapies

1. A compound of formula I:

or a pharmaceutically acceptable salt thereof;

wherein:

n is 0-4;

each R 1 is independently halogen; —NO 2 ; —CN; —OR; —SR; —N + (R) 3 ; —N(R) 2 ; —C(O)R; —CO 2 R; —C(O)C(O)R; —C(O)CH 2 C(O)R; —S(O)R; —S(O) 2 R; —C(O)N(R) 2 ; —SO 2 N(R) 2 ; —OC(O)R; —N(R)C(O)R; —N(R)N(R) 2 ; —N(R)C(═NR)N(R) 2 ; —C(═NR)N(R) 2 ; —C═NOR; —N(R)C(O)N(R) 2 ; —N(R)SO 2 N(R) 2 ; —N(R)SO 2 R; —OC(O)N(R) 2 ; or an optionally substituted group selected from C 1-12 aliphatic; 3- to 14-membered carbocyclyl; 3- to 14-membered heterocyclyl; 6- to 14-membered aryl; or 5- to 14-membered heteroaryl, or:

two R 1 groups on adjacent carbon atoms are taken together with their intervening atoms to form an optionally substituted ring selected from 3- to 14-membered carbocycle; 3- to 14-membered heterocycle; a 6- to 14-membered aryl ring; or a 5- to 14-membered heteroaryl ring;

each R 2 and R 3 is independently hydrogen, —S(═O) 2 OR a , —P(═O)OR a OR b , or —C(═O)R c ; wherein each R a and R b is independently hydrogen, sodium, potassium, an amine cation, or an optionally substituted group selected from C 1-12 aliphatic; 3- to 14-membered carbocyclyl; 3- to 14-membered heterocyclyl; 6- to 14-membered aryl; or 5- to 14-membered heteroaryl; or:

R a and R b are taken together with their intervening atoms to form an optionally substituted 3- to 14-membered heterocycle;

R c is hydrogen, —N(R) 2 ; —OR; —SR; or an optionally substituted group selected from C 1-12 aliphatic; 3- to 14-membered carbocyclyl; 3- to 14-membered heterocyclyl; 6- to 14-membered aryl; or 5- to 14-membered heteroaryl;

R 4 is hydrogen; halogen; —NO 2 ; —OR; —SR; —N + (R) 3 ; —N(R) 2 ; —C(O)R; —CO 2 R; —C(O)C(O)R; —C(O)CH 2 C(O)R; —S(O)R; —S(O) 2 R; —C(O)N(R) 2 ; —SO 2 N(R) 2 ; —OC(O)R; —N(R)C(O)R; —N(R)N(R) 2 ; —N(R)C(═NR)N(R) 2 ; —C(═NR)N(R) 2 ; —C═NOR; —N(R)C(O)N(R) 2 ; —N(R)SO 2 N(R) 2 ; —N(R)SO 2 R; —OC(O)N(R) 2 ; or an optionally substituted group selected from C 1-12 aliphatic; 3- to 14-membered carbocyclyl; 3- to 14-membered heterocyclyl; 6- to 14-membered aryl; or 5- to 14-membered heteroaryl;

R 5 is halogen; —NO 2 ; —CN; —OR; —SR; —N + (R) 3 ; —N(R) 2 ; —C(O)R; —CO 2 R; —C(O)C(O)R; —C(O)CH 2 C(O)R; —S(O)R; —S(O) 2 R; —C(O)N(R) 2 ; —SO 2 N(R) 2 ; —OC(O)R; —N(R)C(O)R; —N(R)N(R) 2 ; —N(R)C(═NR)N(R) 2 ; —C(═NR)N(R) 2 ; —C═NOR; —N(R)C(O)N(R) 2 ; —N(R)SO 2 N(R) 2 ; —N(R)SO 2 R; —OC(O)N(R) 2 ; or an optionally substituted group selected from C 1-12 aliphatic; 3- to 14-membered carbocyclyl; 3- to 14-membered heterocyclyl; or 5- to 14-membered heteroaryl; provided that R 5 is not methyl or ethyl;

each R is independently hydrogen or an optionally substituted group selected from C 1-12 aliphatic; a 3- to 14-membered carbocycle; a 3- to 14-membered heterocycle; a 6- to 14-membered aryl ring; or a 5- to 14-membered heteroaryl ring;

provided that:

(a) when R 2 and R 3 are each acetyl, then R 1 is not acetoxy;

(b) when R 2 and R 3 are each acetyl and R 4 is ethoxycarbonyl, then R 5 is not 2-oxo-propyl; and

(c) when R 2 , R 3 and R 5 are each acetyl, then either R 1 or R 4 is not hydrogen.

2. The compound of claim 1 , wherein n is 0.

3. The compound of claim 1 , wherein n is 1.

4. The compound of claim 1 , wherein R 1 is halogen.

5. The compound of claim 1 , wherein R 2 is hydrogen.

6. The compound of claim 1 , wherein R 2 is -C(═O)R c , wherein R c is optionally substituted C 1-12 aliphatic.

7. The compound of claim 1 , wherein R 2 is —P(═O)OR a OR b , wherein R a and R b are each independently hydrogen, sodium, or potassium.

8. The compound of claim 1 , wherein R 2 is —S(═O) 2 OR a , wherein R a is selected from hydrogen, sodium, or potassium.

9. The compound of claim 1 , wherein R 3 is hydrogen.

10. The compound of claim 1 , wherein R 3 is -C(═O)R c , wherein R c is optionally substituted C 1-12 aliphatic.

11. The compound of claim 1 , wherein R 3 is —P(═O)OR a OR b , wherein R a and R b are each independently hydrogen, sodium, or potassium.

12. The compound of claim 1 , wherein R 3 is —S(═O) 2 OR a , wherein R a is selected from hydrogen, sodium, or potassium.

13. The compound of claim 1 , wherein R 4 is hydrogen.

14. The compound of claim 1 , wherein R 5 is —C(O)R, wherein R is optionally substituted C 1-12 aliphatic.

15. The compound of claim 1 , wherein R 5 is —C(O)R, wherein R is optionally substituted 6- to 14-membered aryl.

16. The compound of claim 14 , wherein R is methyl.

17. The compound of claim 1 , selected from the group consisting of:

18. A pharmaceutical composition comprising a compound of claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient, carrier, or diluent.

19. The pharmaceutical composition of claim 18 , wherein the compound is an amorphous solid.

20. A method of treating a subject suffering from or susceptible to a disease, disorder, or condition, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 .

21. The method of claim 20 , wherein the disease, disorder, or condition is a proliferative disease, disorder, or condition.

22. The method of claim 20 , wherein the disease, disorder, or condition is selected from obesity, an obesity-related disorder or condition, diabetes, metabolic disease, or degenerative disease.

23. The method of claim 21 , wherein the disease, disorder, or condition is associated with mitochondrial dysfunction.

24. The method of claim 21 , wherein the proliferative disease is cancer.

25. The method of claim 21 , further comprising administering to the subject a therapeutically effective amount of a second chemotherapeutic agent.

26. The method of claim 24 , wherein the subject is in clinical remission or, where the subject has been treated by surgery, has limited unresected disease.

27. The method of claim 24 , wherein the cancer is a solid tumor.

28. The method of claim 27 , further comprising treatment of the cancer with radiation therapy.

29. The method of claim 24 , wherein the cancer is selected from the group consisting of colon cancer, lung cancer, bone cancer, pancreatic cancer, stomach cancer, esophageal cancer, skin cancer, brain cancer, liver cancer, ovarian cancer, cervical cancer, uterine cancer, testicular cancer, prostate cancer, bladder cancer, kidney cancer, neuroendocrine cancer, breast cancer, gastric cancer, eye cancer, nasopharyngeal cancer, gallbladder cancer, laryngeal cancer, oral cancer, penile cancer, glandular tumors, rectal cancer, small intestine cancer, head and neck cancer, multiple myeloma, colorectal carcinoma, kaposi sarcoma, ewing's sarcoma, osteosarcoma, leiomyosarcoma, glioma, meningioma, medulloblastoma, melanoma, urethral cancer, and vaginal cancer.

30. The method of claim 29 , wherein the cancer is metastatic.

31. The method of claim 29 , wherein the subject is a mammal.