Aurora kinase inhibitors

1. A compound of formula I:

wherein:

ring A is substituted with one or more groups independently selected from hydroxy, halo, cyano, nitro, (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, methylenedioxy, ethylenedioxy, or (C 2 -C 6 )alkanoyloxy, wherein any (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy is optionally substituted with one or more halo;

R 1 is H, halo, cyano, nitro, (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, methylenedioxy, ethylenedioxy, or (C 2 -C 6 )alkanoyloxy, wherein any (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy is optionally substituted with one or more halo; or R 1 and R 2 taken together are methylenedioxy or ethylenedioxy;

R 2 is H, halo, cyano, nitro, (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, methylenedioxy, ethylenedioxy, or (C 2 -C 6 )alkanoyloxy, wherein any (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy is optionally substituted with one or more halo; or R 1 and R 2 taken together are methylenedioxy or ethylenedioxy; or R 2 and R 3 taken together are methylenedioxy or ethylenedioxy;

R 3 is H, halo, cyano, nitro, (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, methylenedioxy, ethylenedioxy, or (C 2 -C 6 )alkanoyloxy, wherein any (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy is optionally substituted with one or more halo; or R 2 and R 3 taken together are methylenedioxy or ethylenedioxy; or R 3 and R 4 taken together are methylenedioxy or ethylenedioxy; and

R 4 is H, halo, cyano, nitro, (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, methylenedioxy, ethylenedioxy, or (C 2 -C 6 )alkanoyloxy, wherein any (C 1 -C 6 )alkyl, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy is optionally substituted with one or more halo; or R 3 and R 4 taken together are methylenedioxy or ethylenedioxy;

or a salt thereof.

2. The compound of claim 1 which is a compound of formula (Ia):

or a salt thereof.

3. The compound of claim 1 wherein ring A is substituted with one or more (C 1 -C 6 )alkoxy.

4. The compound of claim 1 wherein ring A is 3,4,5-trihydroxyphenyl or 4-nitrophenyl.

5. The compound of claim 1 wherein at least one of R 1 , R 2 , R 3 , and R 4 is other than H.

6. The compound of claim 1 wherein at least one of R 1 , R 2 , R 3 , and R 4 is halo, cyano, nitro, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkoxycarbonyl, or (C 2 -C 6 )alkanoyloxy.

7. The compound of claim 1 wherein at least one of R 1 , R 2 , R 3 , and R 4 is halo.

8. The compound of claim 1 wherein at least one of R 1 , R 2 , R 3 , and R 4 is fluoro or chloro.

9. The compound of claim 1 wherein R 2 is halo.

10. The compound of claim 1 wherein R 2 is fluoro or chloro.

11. The compound of claim 1 wherein R 3 is halo.

12. The compound of claim 1 wherein R 3 is fluoro or chloro.

13. A compound selected from:

and salts thereof.

14. A pharmaceutical composition comprising a compound as described in claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

15. A method of inhibiting Aurora B kinase in an animal in need of such treatment comprising administering a compound as described in claim 1 or a pharmaceutically acceptable salt thereof to the animal.

16. A method of treating a pathological condition associated with Aurora B kinase in an animal comprising administering an effective Aurora B kinase inhibitory amount of a compound as described in claim 1 or a pharmaceutically acceptable salt thereof to the animal.

17. A method of treating cancer in an animal comprising administering a compound as described in claim 1 or a pharmaceutically acceptable salt thereof to the animal.