Pyrazolopyrimidine compounds for the treatment of cancer

1. A method of treating cancer in a subject in need thereof, comprising administering a compound of Formula I:

wherein:

R 1 is aryl, wherein the aryl is unsubstituted or substituted from 1 to 3 times with halo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocyclo, heterocycloalkyl, hydroxyl, alkoxy, alkenyloxy, alkynyloxy, haloalkoxy, cycloalkoxy, cycloalkylalkyloxy, aryloxy, arylalkyloxy, heterocyclooxy, heterocyclolalkyloxy, mercapto, alkyl-S(O) m , haloalkyl-S(O) m , alkenyl-S(O) m , alkynyl-S(O) m , cycloalkyl-S(O) m , cycloalkylalkyl-S(O) m , aryl-S(O) m , arylalkyl-S(O) m , heterocyclo-S(O) m , heterocycloalkyl-S(O) m , amino, carboxy, alkylamino, alkenylamino, alkynylamino, haloalkylamino, cycloalkylamino, cycloalkylalkylamino, arylamino, arylalkylamino, heterocycloamino, heterocycloalkylamino, disubstituted-amino, acylamino, acyloxy, ester, amide, sulfonamide, urea, alkoxyacylamino, aminoacyloxy, nitro or cyano where m=0, 1, 2 or 3;

or R 1 is heteroaryl, wherein the heteroaryl is unsubstituted or substituted from 1 to 3 times with halo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocyclo, heterocycloalkyl, hydroxyl, alkoxy, alkenyloxy, alkynyloxy, haloalkoxy, cycloalkoxy, cycloalkylalkyloxy, aryloxy, arylalkyloxy, heterocyclooxy, heterocyclolalkyloxy, mercapto, alkyl-S(O) m , haloalkyl-S(O) m , alkenyl-S(O) m , alkynyl-S(O) m , cycloalkyl-S(O) m , cycloalkylalkyl-S(O), aryl-S(O) m , arylalkyl-S(O) m , heterocycle-S(O) m , heterocycloalkyl-S(O) m , amino, alkylamino, alkenylamino, alkynylamino, halo alkylamino, cycloalkylamino, cycloalkylalkylamino, arylamino, arylalkylamino, heterocycloamino, heterocycloalkylamino, disubstituted-amino, acylamino, acyloxy, ester, amide; sulfonamide, urea, alkoxyacylamino, aminoacyloxy, nitro or cyano where m=0, 1, 2 or 3;

R 2 is —R 5 R 6 , where R 5 is a covalent bond or C1 to C3 alkyl and R 6 is cycloalkyl, wherein R 6 is optionally substituted from one to two times with independently selected polar groups;

R 3 is —NR 7 R 8 , where R 7 and R 8 are each independently selected from H, alkyl, arylalkyl, and alkoxyalkyl; wherein the alkyl, arylalkyl, or alkoxyalkyl is unsubstituted or substituted from 1 to 3 times with alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, aryl, or heteroaryl; and

R 4 is H, loweralkyl, halo, or loweralkoxy;

or a pharmaceutically acceptable salt thereof, in an amount effective to treat said cancer, wherein said subject is suffering from said cancer and treatment of said cancer is mediated by MER receptor tyrosine kinase activity.

2. The method of claim 1 , wherein R 5 is C1 to C3 alkyl.

3. The method of claim 2 , wherein R 5 is —CH 2 —.

4. The method of claim 1 , wherein R 1 is phenyl, or pyridyl, which phenyl or pyridyl is unsubstituted or substituted from 1 to 3 times with halo, amino, nitro, alkyl, alkoxyl, haloalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl.

5. The method of claim 1 , wherein R 8 is C1-C8 alkyl or C1-C8 arylalkyl; wherein the alkyl or arylalkyl is unsubstituted or substituted from 1 to 3 times with alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, aryl, or heteroaryl.

6. The method of claim 1 , wherein R 6 cyclohexyl.

7. The method of claim 1 , wherein R 6 is substituted once with hydroxyl.

8. The method of claim 1 , wherein R 7 is H.

9. The method of claim 1 , wherein R 8 is loweralkyl.

10. The method of claim 1 , wherein R 4 is H.

11. The method of claim 1 , wherein said compound has the structure:

or a pharmaceutically acceptable salt thereof.

12. The method of claim 1 , wherein the compound has the structure:

or a pharmaceutically acceptable salt thereof.

13. The method of claim 1 , wherein the compound has the structure:

or a pharmaceutically acceptable salt thereof.

14. The method of claim 1 , wherein said cancer is selected from the group consisting of myeloid leukemia, lymphoblastic leukemia, melanoma, breast, lung, colon, liver, gastric, kidney, ovarian, uterine, and brain cancer.

15. A method of treating cancer in a subject in need thereof, comprising administering a compound of Formula I:

wherein:

R 1 is phenyl, which phenyl is unsubstituted or substituted from 1 to 3 times with halo, amino, nitro, alkyl, alkoxyl, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, aryl, or heteroaryl,

R 2 is —R 5 R 6 , where R 5 is a covalent bond or C1 to C3 alkyl and R 6 is cycloalkyl, wherein R 6 is optionally substituted from one to two times with independently selected polar groups;

R 3 is —NR 7 R 8 , where R 7 and R 8 are each independently selected from H, alkyl, arylalkyl, and alkoxyalkyl; wherein the alkyl, arylalkyl, or alkoxyalkyl is unsubstituted or substituted from 1 to 3 times with alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, aryl, or heteroaryl; and

R 4 is H, loweralkyl, halo, or loweralkoxy;

or a pharmaceutically acceptable salt thereof, in an amount effective to treat said cancer, wherein said subject is suffering from said cancer and treatment of said cancer is mediated by MER receptor tyrosine kinase activity.

16. The method of claim 15 , wherein R 6 is cyclohexyl substituted once with hydroxyl.

17. The method of claim 15 , wherein R 7 is H.

18. The method of claim 15 , wherein R 8 is loweralkyl.

19. The method of claim 15 , wherein R 4 is H.

20. The method of claim 15 , wherein said cancer is selected from the group consisting of myeloid leukemia, lymphoblastic leukemia, melanoma, breast, lung, colon, liver, gastric, kidney, ovarian, uterine, and brain cancer.

21. A method of treating cancer in a subject in need thereof, comprising administering a compound of Formula I:

wherein:

R 1 is aryl or heteroaryl; wherein the aryl or heteroaryl is unsubstituted or substituted from 1 to 3 times with halo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocyclo, heterocycloalkyl, hydroxyl, alkoxy, alkenyloxy, alkynyloxy,

haloalkoxy, cycloalkoxy, cycloalkylalkyloxy, aryloxy, arylalkyloxy, heterocyclooxy, heterocyclolalkyloxy, mercapto, alkyl-S(O) m , haloalkyl-S(O) m , alkenyl-S(O) m , alkynyl-S(O) m , cycloalkyl-S(O) m , cycloalkylalkyl-S(O) m , aryl-S(O) m , arylalkyl-S(O) m , heterocyclo-S(O) m , heterocycloalkyl-S(O) m , amino, carboxy, alkylamino, alkenylamino, alkynylamino, haloalkylamino, cycloalkylamino, cycloalkylalkylamino, arylamino, arylalkylamino, heterocycloamino, heterocycloalkylamino, disubstituted-amino, acylamino, acyloxy, ester, amide, sulfonamide, urea, alkoxyacylamino, aminoacyloxy, nitro or cyano where m=0, 1, 2 or 3;

R 2 is R 5 R 6 , where R 5 is a covalent bond or C1 to C3 alkyl and R 6 is cycloalkyl, wherein R 6 is optionally substituted from one to two times with independently selected polar groups;

R 3 is —NR 7 R 8 , where R 7 is selected from H, alkyl, arylalkyl, and alkoxyalkyl; and R 8 is C3-C8 cycloalkyl, wherein the cycloalkyl is unsubstituted or substituted from 1 to 3 times with alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, aryl, or heteroaryl; and

R 4 is H, loweralkyl, halo, or loweralkoxy;

or a pharmaceutically acceptable salt thereof, in an amount effective to treat said cancer, wherein said subject is suffering from said cancer and treatment of said cancer is mediated by MER receptor tyrosine kinase activity.

22. The method of claim 21 , wherein said cancer is selected from the group consisting of myeloid leukemia, lymphoblastic leukemia, melanoma, breast, lung, colon, liver, gastric, kidney, ovarian, uterine, and brain cancer.