3-alkyl-4-amido-bicyclic [4,5,0] hydroxamic acids as hdac inhibitors

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• X1 is O;
• X2 and X4 are each CR1R2;
• X3 is CR1′R2′;
• Y1 and Y4 are not bound to —C(O)NHOH and are each CR1;
• Y2 and Y3 are CR1 when not bonded to —C(O)NHOH and Y2 and Y3 are C when bonded to —C(O)NHOH;
• L is selected from the group consisting of —C(O)—, —C(O)(CR1R2)m—, and —C(O)(CR1R2)mO—, wherein L is bound to the ring nitrogen through the carbonyl group;
• R is independently selected from the group consisting of —H, —C1-C6 alkyl, —C2-C6 alkenyl, —C4-C8 cycloalkenyl, —C2-C6 alkynyl, —C3-C8 cycloalkyl, —C5-C12 spirocyclyl, heterocyclyl, spiroheterocyclyl, aryl, and heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, spirocyclyl, heterocyclyl, spiroheterocyclyl, aryl, or heteroaryl is optionally substituted with one or more substituents selected from the group consisting of —OH, halogen, oxo, —NO2, —CN, —R1, —R2, —OR3, —NHR3, —NR3R4, —S(O)2NR3R4, —S(O)2R1, —C(O)R1, —CO2R1, —NR3S(O)2R1, —S(O)R1, —S(O)NR3R4, —NR3S(O)R1, heterocyclyl, aryl, and heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O, with the proviso that R is not bound to L via a nitrogen atom;
• R1 and R2 are independently, at each occurrence, selected from the group consisting of —H, —R3, —R4, —C1-C6 alkyl, —C2-C6 alkenyl, —C3-C8 cycloalkenyl, —C2-C6 alkynyl, —C3-C8 cycloalkyl, heterocyclyl, aryl, heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O, —OH, halogen, —NO2, —CN, —NHC1-C6 alkyl, —N(C1-C6 alkyl)2, —S(O)2N(C1-C6 alkyl)2, —N(C1-C6 alkyl)S(O)2R5, —S(O)2(C1-C6 alkyl), —(C1-C6 alkyl)S(O)2R5, —C(O)C1-C6 alkyl, —CO2C1-C6 alkyl, —N(C1-C6 alkyl)S(O)2C1-C6 alkyl, and —(CHR5)nNR3R4, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl, or heteroaryl is optionally substituted with one or more substituents selected from the group consisting of —OH, halogen, —NO2, oxo, —CN, —R5, —OR3, —NHR3, —NR3R4, —S(O)2N(R3)2N(R3)2, —S(O)2R5, —C(O)R5, —CO2R5, —NR3S(O)2R5, —S(O)R5, —S(O)NR3R4, —NR3S(O)R5, heterocyclyl, aryl, and heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O;
• and one of R1 and R2 of X2 combines with one of R1 and R2 of X4 to form a bridging cycloalkyl or heterocycloalkyl ring;
• R1′ and R2′ are independently, at each occurrence, selected from the group consisting of —H, —C1-C6 alkyl, —C2-C6 alkenyl, —C3-C8 cycloalkenyl, —C2-C6 alkynyl, —C3-C8 cycloalkyl, heterocyclyl, —OH, halogen, —NO2, —CN, —NHC1-C6 alkyl, —N(C1-C6 alkyl)2, —S(O)2N(C1-C6 alkyl)2, —N(C1-C6 alkyl)S(O)2R5, —S(O)2(C1-C6 alkyl), —(C1-C6 alkyl)S(O)2R5, —C(O)C1-C6 alkyl, —CO2C1-C6 alkyl, —N(C1-C6 alkyl)S(O)2C1-C6 alkyl, and —(CHR5)nNR3R4, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, or heterocyclyl is optionally substituted with one or more substituents selected from the group consisting of —OH, halogen, —NO2, oxo, —CN, —R5, —OR3, —NHR3, —NR3R4, —S(O)2N(R3)2, —S(O)2R5, —C(O)R5, —CO2R5, —NR3S(O)2R5, —S(O)R5, —S(O)NR3R4, —NR3S(O)R5, heterocyclyl, aryl, and heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O;
• R3 and R4 are independently, at each occurrence, selected from the group consisting of —H, —C1-C6 alkyl, —C2-C6 alkenyl, —C3-C8 cycloalkenyl, —C2-C6 alkynyl, —C3-C8 cycloalkyl, heterocyclyl, aryl, heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O, —S(O)2N(C1-C6 alkyl)2, —S(O)2(C1-C6 alkyl), —(C1-C6 alkyl)S(O)2R5, —C(O)C1-C6 alkyl, —CO2C1-C6 alkyl, and —(CHR5)nN(C1-C6 alkyl)2, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is optionally substituted with one or more substituents selected from the group consisting of —OH, halogen, —NO2, oxo, —CN, —R5, —O(C1-C6 alkyl), —NH(C1-C6 alkyl), —N(C1-C6 alkyl)2, —S(O)2N(C1-C6 alkyl)2, —S(O)2NHC1-C6 alkyl, —C(O)C1-C6 alkyl, —CO2C1-C6 alkyl, —N(C1-C6 alkyl)S(O)2C1-C6 alkyl, —S(O)R5, —S(O)N(C1-C6 alkyl)2, —N(C1-C6 alkyl)S(O)R5, heterocyclyl, aryl, and heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O;
• R5 is independently, at each occurrence, selected from the group consisting of —H, —C1-C6 alkyl, —C2-C6 alkenyl, —C3-C8 cycloalkenyl, —C2-C6 alkynyl, —C3-C8 cycloalkyl, heterocyclyl, aryl, heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, and O, —OH, halogen, —NO2, —CN, —NH(C1-C6 alkyl), —N(C1-C6 alkyl)2, —S(O)2NH(C1-C6 alkyl), —S(O)2N(C1-C6 alkyl)2, —S(O)2C1-C6 alkyl, —C(O)C1-C6 alkyl, —CO2C1-C6 alkyl, —N(C1-C6 alkyl)SO2C1-C6 alkyl, —S(O)(C1-C6 alkyl), —S(O)N(C1-C6 alkyl)2, —N(C1-C6 alkyl)S(O)(C1-C6 alkyl), and —(CH2)nN(C1-C6 alkyl)2;
• each n is independently and at each occurrence an integer from 0 to 6;
• and
• each m is independently and at each occurrence an integer from 1 to 6.