Nitrogen-based camptothecin derivatives

1. A compound of the formula:

wherein R is R a R b N—(CH 2 ) m , m is an integer from 1-10, and each of R a and R b is independently

phenyl optionally substituted with from one to five substituents independently selected from the group consisting of halo, lower alkyl, lower alkoxy, hydroxy, cyano, nitro, amino, halogenated lower alkyl, halogenated lower alkoxy, formyl, lower alkyl carbonyl, hydroxycarbonyl, lower alkylcarbonyloxy, benzyloxy, optionally substituted piperidino, lower alkoxycarbonyl, and lower alkylcarbonylamino;

cycloalkyl of 3-7 carbons, optionally substituted with one to five substituents independently selected from the group consisting of halo, lower alkyl, lower alkoxy, hydroxy, cyano, nitro, amino, halogenated lower alkyl, halogenated lower alkoxy, hydroxycarbonyl, lower alkoxycarbonyl, lower alkylcarbonyloxy, and lower alkylcarbonylamino;

lower alkoxy; or

R a R b together with N form a cyclic amine or imide ring; and

R 2 is —CH 2 NR 7 R 8 (where R 7 and R 8 together with N are cyclic amino), butoxyiminomethyl, hydrogen, or together with R 3 is —CH 2 (NR 12 R 13 )—CH 2 —CH 2 — (where R 12 and

R 13 each is independently hydrogen or lower alkyl);

R 3 is hydrogen, trialkylsilylethylene or together with R 2 is —CH 2 (NR 12 R 13 )—CH 2 —CH 2 — (where R 12 and R 13 each is independently hydrogen or lower alkyl);

R 4 is hydrogen, lower alkyl or together with R 5 is ethylenedioxy;

R 5 is hydrogen, halo or together with R 4 is ethylenedioxy; and

R 6 is hydrogen,

wherein:

if R 2 is —CH 2 NR 7 R 8 (where R 7 and R 8 taken together with —N— represent a cyclic amino) then R 3 and R 6 are H and R 4 and R 5 taken together represent ethylenedioxy;

if R 2 is butoxyiminomethyl then each of R 3 , R 4 , R 5 and R 6 is H;

if R 2 is hydrogen then R 3 is trialkylsilylethylene and each of R 4 , R 5 , and R 6 is H; and

if R 2 and R 3 together represent —CH(NR 12 R 13 )—CH 2 —CH 2 — then R 4 is lower alkyl, R 5 is halo, and R 6 is H, wherein R 12 and R 13 each is independently H or lower alkyl.

2. The compound of claim 1 , wherein n is 2 and R a R b taken together with N form a cyclic amine or imide ring.

3. The compound of claim 2 , wherein R a R b taken together with N form a six-membered cyclic amine.

4. The compound of claim 3 , wherein the cyclic amine is piperazine optionally substituted at the 4-position with phenyl, substituted phenyl, benzyl, or substituted benzyl.

5. The compound of claim 4 , wherein R 2 is —CH 2 NR 7 R 8 (where R 7 and R 8 taken together with —N— represent 4-methylpiperazinomethylene) when R 3 and R 6 are H and R 4 and R 5 taken together represent ethylenedioxy.

6. The compound of claim 4 , wherein R 2 is butoxyiminomethyl when each of R 3 , R 4 , R 5 and R 6 is H.

7. The compound of claim 4 , wherein R 3 is trimethylsilylethylene when each of R 2 , R 4 , R 5 , and R 6 is H.

8. The compound of claim 4 , wherein R 2 and R 3 together represent —CH(NH 2 )—CH 2 —CH 2 — when R 4 is methyl, R 5 is fluoro, and R 6 is H.

9. The compound of claim 2 , wherein R a R b taken together with —N— form an imide ring.

10. The compound of claim 9 , wherein R 2 is —CH 2 NR 7 R 8 (where R 7 and R 8 taken together with —N— represent 4-methylpiperazinomethylene) when R 3 and R 6 are H and R 4 and R 5 taken together represent ethylenedioxy.

11. The compound of claim 9 , wherein R 2 is butoxyiminomethyl when each of R 3 , R 4 , R 5 and R 6 is H.

12. The compound of claim 9 , wherein R 3 is trimethylsilylethylene when each of R 2 , R 4 , R 5 , and R 6 is H.

13. The compound of claim 9 , wherein R 2 and R 3 together represent —CH(NH 2 )—CH 2 —CH 2 — when R 4 is methyl, R 5 is fluoro, and R 6 is H.

14. A pharmaceutical composition useful for treating colon or breast cancer in a warm-blooded animal, which composition comprises a compound as defined in claim 1 in combination with a pharmaceutically acceptable excipient.

15. The pharmaceutical composition of claim 14 suitable for oral administration.

16. The pharmaceutical composition of claim 14 suitable for IV administration.

17. The pharmaceutical composition of claim 14 suitable for IM administration.

18. A method for treating colon or breast cancer in a warm-blooded animal, which method comprises administering a therapeutically effective amount of a compound as defined in claim 1 .

19. The method of claim 18 , wherein the compound is administered orally.

20. The method of claim 18 , wherein the compound is administered IV.

21. The method of claim 18 , wherein the compound is administered parenterally.

22. A process of preparing a compound of claim 1 , which comprises reacting

(a) a compound of the formula R—C(O)X, wherein R is R a R b N(CH 2 ) 2 as defined as in claim 1 , and X is hydroxy, chloride, or R—C(O)—O (where R is defined hereinbefore) with

(b) a compound of the formula:

wherein R 2 , R 3 , R 4 , R 5 , and R 6 are defined in claim 1 .

23. The process of claim 22 wherein the reacting takes place in the presence of the coupling agent, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, hydrochloride, and the catalyst, 4-(dimethylamino) pyridine.

24. A pharmaceutical composition useful for treating colon or breast cancer in a warm-blooded animal, which composition comprises a compound as defined in claim 1 , formulated for liposomal delivery.

25. The composition of claim 24 , wherein n is 2 and R a R b taken together with N form a cyclic amine or imide ring.

26. The composition of claim 25 , wherein R a R b taken together with N form a six-membered cyclic amine.

27. The composition of claim 25 , wherein the cyclic amine is piperazine optionally substituted at the 4-position with phenyl, substituted phenyl, benzyl, or substituted benzyl.

28. The composition of claim 25 , wherein R a R b taken together with N form an imide ring.

29. A method for modulating topoisomerase comprising contacting a compound as defined in claim 1 with a topoisomerase I.