Bicyclic [4,6,0] hydroxamic acids as HDAC inhibitors

A compound of Formula II:

• or a pharmaceutically acceptable salt thereof, wherein:
• X1 is O;
• X2, X3, X4 and X5 are each CR1R2;
• Y1 and Y4 are each independently N or CR1;
• one of Y2 and Y3 is C bonded to C(O)NHOH and the other of Y2 and Y3 is N or CR1;
• L is a bond, —(CR1R2)n—, —C(O)—, —C(O)O—, —C(O)NR3—, —S(O)2—, —S(O)2NR3—, —S(O)—, —S(O)NR3—, —C(O)(CR1R2)nO—, or —C(O)(CR1R2)n—;
• R is independently, and at each occurrence, —H, —C1-C6alkyl, —C2-C6alkenyl, —C4-C8cycloalkenyl, —C2-C6alkynyl, —C3-C8cycloalkyl, —C5-C12spirocycle, heterocyclyl, spiroheterocyclyl, aryl, or heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, or O, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, spirocycle, heterocyclyl, spiroheterocyclyl, aryl, or heteroaryl is optionally substituted with one or more —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, heterocycle, aryl, or heteroaryl, with the proviso that when L is —C(O)— the spiroheterocyclyl is not bound to L via a nitrogen atom;
• R1 and R2 are independently, and at each occurrence, —H, R3, R4, —C1-C6alkyl, —C2-C6alkenyl, —C4-C8cycloalkenyl, —C2-C6alkynyl, —C3-C8cycloalkyl, heterocyclyl, aryl, heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, or O, —OH, halogen, —NO2, —CN, —NH(C1-C6alkyl), —N(C1-C6alkyl)2, —S(O)2N(C1-C6alkyl)2, —N(C1C6alkyl)S(O)2R5, —S(O)2(C1-C6alkyl), —(C1-C6alkyl)S(O)2R5, —C(O)C1-C6alkyl, —N(C1-C6alkyl)S(O)2(C1-C6alkyl), or —(CHR5)nNR3R4, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl, or heteroaryl is optionally substituted with one or more substituents selected from —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, or heteroaryl;
• R3 and R4 are independently, and at each occurrence, —H, —C1-C6alkyl, —C2-C6alkenyl, —C4-C8cycloalkenyl, —C2-C6alkynyl, —C3-C8cycloalkyl, heterocyclyl, aryl, heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, or O, —S(O)2N(C1-C6alkyl)2, —S(O)2(C1-C6alkyl), —(C1-C6alkyl)S(O)2R5, —C(O)C1-C6alkyl, —CO2C1-C6alkyl, or —(CHR5)nN(C1-C6alkyl)2, wherein each alkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is optionally substituted with one or more substituents selected from —OH, halogen, —NO2, oxo, —CN, —R5, —O(C1-C6)alkyl, —NH(C1-C6alkyl), N(C1-C6alkly)2, —S(O)2N(C1-C6alkyl)2, —S(O)2NH(C1-C6alkyl), —C(O)C1-C6alkyl, —CO2C1-C6alkyl, —N(C1-C6alkyl)S(O)2C1-C6alkyl, —S(O)R5, —S(O)N(C1-C6alkyl)2, —N(C1-C6alkyl)S(O)R5, heterocycle, aryl, or heteroaryl containing 1-5 heteroatoms selected from the group consisting of N, S, P, or O;
• R5 is independently, and at each occurrence, —H, —C1-C6alkyl, —C2-C6alkenyl, —C3-C8cycloalkenyl, —C2-C6alkynyl, —C3-C8cycloalkyl, heterocyclyl, aryl, heteroaryl, —OH, halogen, —NO2, —CN, —NH(C1-C6alkyl), —N(C1-C6alkyl)2, —S(O)2NH(C1-C6alkyl), —S(O)2N(C1-C6alkyl)2, —S(O)2(C1-C6alkyl), —C(O)C1-C6alkyl, —CO2C1-C6alkyl, —N(C1-C6alkyl)SO2(C1-C6alkyl), —S(O)(C1-C6alkyl), —S(O)N(C1-C6alkyl)2, —N(C1-C6alkyl)S(O)(C1-C6alkyl) or (CH2)nN(C1-C6alkyl)2;
• and
• n is independently and at each occurrence an integer from 0 to 6.