DNA-PK inhibitors

1. A compound having the formula:

or a pharmaceutically acceptable salt thereof, wherein Ring A is a ring system selected from

Ring B is a ring system selected from

wherein Ring B is optionally substituted with up to 4 fluorine atoms or up to two C 1-4 alkyl optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups;

X is NH or O;

each of R 1 and R 2 is, independently, hydrogen, —C(O)NHR 4 , —C(O)OR 4 , —NHC(O)R 4 , —NHC(O)OR 4 , —NHC(O)NHR 4 , —NHS(O) 2 R 4 , —NHR 4 , or —OR 4 , wherein R 1 and R 2 cannot simultaneously be hydrogen, and wherein R 1 and R 2 and the intervening carbon atom can form a dioxane or dioxolane ring;

R 3 is hydrogen, C 1-4 alkyl, fluoro, chloro, OC 1-2 alkyl, C(O)OH, C(O)OC 1-2 alkyl, CN, C(O)NHC 1-2 alkyl, or C(O)NH 2 , wherein each of said R 3 alkyl is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups;

R 4 is hydrogen, C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-5 cycloalkyl, phenyl, a 5-10-membered monocyclic or bicyclic heteroaryl ring selected from pyrrole, imidazole, pyrazole, triazole, thiazole, isothiazole, oxazole, pyridine, pyrimidine, pyrimidinone, pyrazine, pyridazine, or quinoline, or a 4-10-membered monocyclic or bicyclic heterocyclyl ring selected from oxetane, tetrahydrofuran, tetrahydropyran, dihydroisoxazole, pyrimidine-2,4(1H,3H)-dione, dihydrofuropyrimidine, dihydropyranopyrimidine, dihydropyrrolopyrimidine, tetrahydropteridine, or tetrahydropyridopyrimidine, wherein each of said R 4 groups is optionally substituted with Br, Cl, up to three fluorine atoms, up to three C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-6 cycloalkyl, an oxetane ring, a tetrahydrofuran ring, a dihydropyran ring, a tetrahydropyran ring, a pyrrolidine ring, a pyrazole ring, a triazole ring, a tetrazole ring, an oxadiazole ring, CN, CH 2 OR 5 , C(O)R 5 , C(O)N(R 5 ) 2 , C(O)OR 5 , NO 2 , NHC(O)R 5 , N(R 5 ) 2 , or up to two OR 5 , wherein each of said optional R 4 substituents is optionally substituted with up to 3 fluorine atoms, up to two C 1-4 alkyl groups, up to two OH groups, up to two OC 1-4 alkyl groups, or up to two SC 1-4 alkyl groups; and

each R 5 is, independently, hydrogen, C 1-4 alkyl, a 5-6-membered heteroaryl selected from imidazole, triazole, thiazole, pyridine, or pyrimidine, a 4-6-membered heterocyclyl selected from oxetane, tetrahydrofuran, or tetrahydropyran, and each R 5 group is optionally substituted with chloro, up to three fluorine atoms, up to two C 1-2 alkyl, CH 2 OH, CN, up to two OH, up to two OC 1-2 alkyl, a spirooxetane, pyrrolidine, or triazole, or two R 5 groups together with the intervening nitrogen atom form a morpholine ring, azetidine ring, pyrrolidine ring, piperidine ring, or piperazine ring, wherein each of said rings is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups.

2. The compound according to claim 1 , wherein X is NH.

3. The compound according to claim 2 having the following formula:

or a pharmaceutically acceptable salt thereof.

4. The compound according to claim 3 having the following formula:

or a pharmaceutically acceptable salt thereof.

5. The compound according to claim 2 having the following formula:

or a pharmaceutically acceptable salt thereof.

6. The compound according to claim 5 having the following formula:

or a pharmaceutically acceptable salt thereof.

7. The compound according to claim 6 , wherein

R 3 is hydrogen, C 1-4 alkyl, fluoro, chloro, OC 1-2 alkyl, C(O)OH, C(O)OC 1-2 alkyl, CN, C(O)NHC 1-2 alkyl, or C(O)NH 2 , wherein each of said R 3 alkyl is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups;

R 4 is hydrogen, C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-5 cycloalkyl, phenyl, a 5-10-membered monocyclic or bicyclic heteroaryl ring selected from pyrrole, imidazole, pyrazole, triazole, thiazole, isothiazole, oxazole, pyridine, pyrimidine, pyrimidinone, pyrazine, pyridazine, or quinoline, or a 4-10-membered monocyclic or bicyclic heterocyclyl ring selected from oxetane, tetrahydrofuran, tetrahydropyran, dihydroisoxazole, pyrimidine-2,4(1H,3H)-dione, dihydrofuropyrimidine, dihydropyranopyrimidine, dihydropyrrolopyrimidine, tetrahydropteridine, or tetrahydropyridopyrimidine;

each of said R 4 groups is optionally substituted with Br, Cl, up to three fluorine atoms, up to three C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-6 cycloalkyl, an oxetane ring, a tetrahydrofuran ring, a dihydropyran ring, a tetrahydropyran ring, a pyrrolidine ring, a pyrazole ring, a triazole ring, a tetrazole ring, an oxadiazole ring, CN, CH 2 OR 5 , C(O)R 5 , C(O)N(R 5 ) 2 , C(O)OR 5 , NO 2 , NHC(O)R 5 , N(R 5 ) 2 , or up to two OR 5 , wherein each of said optional R 4 substituents is optionally substituted with up to 3 fluorine atoms, up to two C 1-4 alkyl groups, up to two OH groups, up to two OC 1-4 alkyl groups, or up to two SC 1-4 alkyl groups; and

each R 5 is, independently, hydrogen, C 1-4 alkyl, a 5-6-membered heteroaryl selected from imidazole, triazole, thiazole, pyridine, or pyrimidine, a 4-6-membered heterocyclyl selected from oxetane, tetrahydrofuran, or tetrahydropyran, and each R 5 group is optionally substituted with chloro, up to three fluorine atoms, up to two C 1-2 alkyl, CH 2 OH, CN, up to two OH, up to two OC 1-2 alkyl, pyrrolidine, or triazole, or two R 5 groups together with the intervening nitrogen atom form a morpholine ring, azetidine ring, pyrrolidine ring, piperidine ring, or piperazine ring, wherein each of said rings is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups.

8. The compound according to claim 7 having formula:

or a pharmaceutically acceptable salt thereof.

9. The compound according to claim 1 , wherein X is O.

10. The compound according to claim 9 having the following formula:

or a pharmaceutically acceptable salt thereof.

11. The compound according to claim 10 having the following formula:

or a pharmaceutically acceptable salt thereof.

12. The compound according to claim 10 having the following formula:

or a pharmaceutically acceptable salt thereof.

13. The compound according to claim 9 having the following formula:

or a pharmaceutically acceptable salt thereof.

14. The compound according to claim 13 having the following formula:

or a pharmaceutically acceptable salt thereof.

15. The compound according to claim 13 having the following formula:

or a pharmaceutically acceptable salt thereof, wherein Y is O or NH.

16. The compound according to claim 13 having the following formula:

or a pharmaceutically acceptable salt thereof.

17. The compound according to claim 16 , wherein

R 3 is hydrogen, C 1-4 alkyl, fluoro, chloro, OC 1-2 alkyl, C(O)OH, C(O)OC 1-2 alkyl, CN, C(O)NHC 1-2 alkyl, or C(O)NH 2 , wherein each of said R 3 alkyl is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups;

R 4 is hydrogen, C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-5 cycloalkyl, phenyl, a heteroaryl ring system selected from pyrrole, imidazole, pyrazole, triazole, thiazole, isothiazole, oxazole, pyridine, pyrimidine, pyrimidinone, pyrazine, pyridazine, or quinoline, or a heterocyclic ring selected from oxetane, tetrahydrofuran, tetrahydropyran, dihydroisoxazole, pyrimidine-2,4(1H,3H)-dione, dihydrofuropyrimidine, dihydropyranopyrimidine, dihydropyrrolopyrimidine, tetrahydropteridine, or tetrahydropyridopyrimidine;

each of said R 4 groups except hydrogen is optionally substituted with Br, Cl, up to three fluorine atoms, up to three C 1-4 alkyl, up to two C 0-4 alkyl-R 5 , up to two C 0-4 alkyl-O—O 0-4 alkyl-R 5 , C 2-4 alkenyl, C 2-4 alkenyl, C 2-4 alkynyl, C 3-6 cycloalkyl, CN, NO 2 , C(O)R 5 , C(O)N(R 5 ) 2 , C(O)OC 0-4 alkyl-R 5 , NHC(O)R 5 , or N(R 5 ) 2 , a heterocyclic ring system selected from oxetane, azetidine tetrahydrofuran, dihydropyran, tetrahydropyran, a heteroaromatic ring system selected from pyrrolidine, pyrazole, triazole, tetrazole, or oxadiazole, wherein each of said optional R 4 substituents is optionally substituted with up to 3 fluorine atoms, up to two C 1-4 alkyl groups, up to two OH groups, up to two OC 1-4 alkyl groups, or up to two SC 1-4 alkyl groups; and

each R 5 is, independently, hydrogen, C 1-4 alkyl, C 3-5 cycloalkyl, a 5-6-membered heteroaryl selected from imidazole, triazole, thiazole, pyridine, or pyrimidine, a 4-6-membered heterocyclyl selected from oxetane, tetrahydrofuran, or tetrahydropyran, and each R 5 group is optionally substituted with chloro, up to three fluorine atoms, up to two C 1-2 alkyl, CH 2 OH, CN, up to two OH, up to two OC 1-2 alkyl, pyrrolidine, or triazole, or two R 5 groups together with an intervening nitrogen atom form a morpholine ring, azetidine ring, pyrrolidine ring, piperidine ring, or piperazine ring, wherein each of said rings is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC 1-2 alkyl groups.

18. A compound having the formula:

or a pharmaceutically acceptable salt thereof, wherein

R 3 is hydrogen, C 1-4 alkyl, fluoro, chloro, OC 1-2 alkyl, or CN, wherein each of said R 3 alkyl is optionally substituted with up to 3 fluorine atoms;

R 4 is

X 1 is N, CH, CF, CCl, or CC 1-2 alkyl optionally substituted with up to 3 fluorine atoms;

X 2 is N, CR 4c

each of R 4a , R 4b , and R 4c is, independently, hydrogen, F, Cl, Br, CN, NO 2 , C 1-4 alkyl, C 0-4 alkyl-C 3-5 cycloalkyl, C 0-4 alkyl-O—C 1-4 alkyl, C 0-4 alkyl-O—O 0-4 alkyl-C 3-5 cycloalkyl, C 2-4 alkenyl, C 2-4 alkynyl, C(O)OC 1-4 alkyl, C(O)OC 0-4 alkyl-C 3-5 cycloalkyl, C(O)NH 2 , C(O)NHC 1-4 alkyl, C(O)N(C 1-4 alkyl) 2 , C(O)NH(C 0-4 alkyl-C 3-5 cycloalkyl), a heterocyclic ring system selected from oxetane, azetidine, tetrahydrofuran, dihydropyran, tetrahydropyran, morpholine, piperidine, or piperazine, or a heteroaryl ring system selected from furan, oxazole, oxadiazole, pyrrole, pyrazole, triazole, or tetrazole, or R 4c , R 4a , and the intervening atoms form a dihydrofuran, a dihydropyran, or a tetrahydropiperidine heterocyclic ring system;

wherein each of said R 4a , R 4b , or R 4c heterocyclic or heteroaryl ring systems is optionally substituted with up to four fluorine atoms, up to two C 1-4 alkyl, a C(O)C 1-4 alkyl, a C(O)OC 1-4 alkyl, or a C(O)OC 0-4 alkyl-C 3-5 cycloalkyl; and

wherein each of said R 4a , R 4b , or R 4c alkyl or cycloalkyl is optionally substituted with up to 2 non-geminal OH groups or up to 3 fluorine atoms.

19. The compound according to claim 1 wherein

20. A compound represented by a structural formula selected from the group consisting of or a pharmaceutically acceptable salt thereof:

21. A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable excipient.

22. The compound of claim 18 , wherein X 1 is N or CH.

23. A pharmaceutical composition comprising a compound of claim 18 and a pharmaceutically acceptable excipient.

24. A pharmaceutical composition comprising a compound of claim 20 and a pharmaceutically acceptable excipient.

25. A pharmaceutical composition comprising a compound of claim 23 and a pharmaceutically acceptable excipient.