Dna-pk inhibitors

A compound of Formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• Ring A is
• Ring B is
• wherein Ring B is optionally substituted with up to 4 fluorine atoms, up to two OH,or up to two C1-4alkyl which is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two —OC1-2alkyl groups;
• Ring C is a cyclohexane or a cyclobutane ring;
• X is —NH—, —O—, or —OC1-4alkyl-;
• each of R1 and R2 is, independently, hydrogen, —C(O)NHR4, —C(O)OR4, —NHC(O)R4, —NHC(O)OR4, —NHC(O)NHR4, —NHS(O)2R4, —C0-4alkyl-NHR4, or —OR4, wherein R1 and R2 cannot simultaneously be hydrogen, and wherein R1 and R2 and the intervening carbon atom can form a dioxane or dioxolane ring;
• R3 is hydrogen, —C1-4alkyl, fluoro, chloro, —OC1-2alkyl, —C(O)H, —C(O)OH, —C(O)OC1-2alkyl, —CN, —C(O)NHC1-2alkyl, or —C(O)NH2, wherein each of said R3alkyl is optionally substituted with up to 3 fluorine atoms, up to two OH, or up to two OC1-2alkyl groups;
• R4 is hydrogen, C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C3-5cycloalkyl, phenyl, a 5-10-membered monocyclic or bicyclic heteroaryl ring selected from pyrrole, imidazole, pyrazole, triazole, thiazole, isothiazole, oxazole, pyridine, pyrimidine, pyrimidinone, pyrazine, pyridazine, and 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, and tetrahydropyridopyrimidine, wherein each of said R4 groups is optionally substituted with up to four Br, Cl, F, or C1-4alkyl, up to three CN, NO2, C2-4alkenyl, C2-4alkynyl, C3-6cycloalkyl, C0-4alkyl-C3-5 cycloalkyl, C0-4alkyl-O—C1-4alkyl, C0-4alkyl-O—C0-4alkyl-C3-5 cycloalkyl, C(O)OC1-4alkyl, C(O)OC0-4alkyl-C3-5cycloalkyl, CO-4alkyl-C(O)NH2, C(O)NHC1-4alkyl, C(O)N(C1-4alkyl)2, C(O)NH(C0-4alkyl-C3-5cycloalkyl), CH2OR5, C0-4alkyl-C(O)R5, C0-4alkyl-C(O)N(R5)2, C0-4alkyl-C(O)OR5, C0-4alkyl-NHC(O)R5, C0-4alkyl-N(R5)2, a heterocyclic ring system selected from oxetane, azetidine, tetrahydrofuran, dihydropyran, tetrahydropyran, morpholine, piperidine, pyrrolidine of and piperazine, a heteroaryl ring system selected from furan, oxazole, oxadiazole, pyrrole, pyrazole, triazole, oxadiazole and tetrazole, or up to two OR5, wherein each of said optional R4 substituents is optionally substituted with up to four fluorine atoms, up to two C1-4alkyl groups, up to two OH groups, up to two OC1-4alkyl groups, up to two SCi1-4alkyl groups, a C(O)C1-4alkyl, a C(O)OC1-4alkyl, or a C(O)OC0-4alkyl-C3-5cycloalkyl;
• and
• each R5 is, independently, hydrogen, C1-4alkyl, a 5-6-membered heteroaryl selected from imidazole, triazole, thiazole, pyridine, and pyrimidine, or a 4-6-membered heterocyclyl selected from oxetane, tetrahydrofuran, and tetrahydropyran, and each R5 group is optionally substituted with chloro, up to three fluorine atoms, up to two C1-2alkyl, CH2OH, CN, up to two OH, up to two OC1-2alkyl, a spirooxetane, pyrrolidine, or triazole, or two R5 groups together with the intervening nitrogen atom form a morpholine ring, azetidine ring, pyrrolidine ring, piperidine ring, or piperazine ring.