Unsaturated nitrogen heterocyclic compounds useful as pde10 inhibitors

A compound of formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• X1 is N or CR6;
• X2 is N or CR2;
• X3 is N or CR3;
• X4 is N or CR6;
• X5 is N or CR6;
• wherein 1 to 2 of X1, X2, X3, X4 and X5 are N;
• R1 is halo, C1-8alk, C1-4haloalk, —ORc, —N(Ra)C(═O)Rb, —C(═O)Ra, —C(═O)Rc, —C(═O)—O—Ra, —NRaRc, —N(Rc)C(═O)Rb, —N(Ra)C(═O)Rc, —C(═O)NRaRb, —C(═O)NRaRc, or C0-4alk-L1;
• wherein said C1-8alk group is substituted by 0, 1, 2 or 3 groups which are halo, C1-3haloalk, —OH, —OC1-4alk, —NH2, —NHC1-4alk, —OC(═O)C1-4alk, or —N(C1-4alk)C1-4alk;
• Y is a C0-4alk, —C(═O), SO, or SO2;
• each R2 and R3 is independently R1, H, halo, CN, OH, —OC1-4alk, C1-4alk, C1-4haloalk, —C1-6alkORa, —C(═O)C1-4alk, —C(═O)NRaRa, —C0-4alkNH—C(═O)Ra, or Rc;
• or alternatively the ring containing X1, X2, X3, X4 and X5 can be fused to ring A, ring B, or ring C;
• each having the formula:
• wherein each said ring A, ring B, or ring C is a fused 4- to 6-membered-saturated, -partially saturated, or -unsaturated-carbocyclic or -heterocyclic ring containing 0, 1, 2, or 3 heteroatoms;
• and is substituted by 0, 1, or 2 R10 groups;
• R4a is H, OH, halo, C1-4alk, or C1-4haloalk;
• R4b is halo, CN, OH, OC1-4alk, C1-4alk, C1-4haloalk, or oxo;
• R5 is —C1-6alkORa, 5- to 6-membered heteroaryl, unsaturated 9- to 10-membered bicyclo-heterocyclic ring, or 11- to 15-membered tricyclo-heterocyclic ring;
• R5 ring is substituted by 0, 1, 2, 3, or 4 R8 groups;
• R6 is independently R1, H, halo, CN, OH, OC1-4alk, C1-4alk or C1-4haloalk;
• m is 0, 1, 2, 3, or 4;
• each of p and q is independently 0, 1, 2, 3, 4, 5, or 6;
• wherein the sum of p and q is 2 to 6;
• the ring containing p and q contains 0, 1, or 2 double bonds;
• Ra is independently H or Rb;
• Rb is independently phenyl, benzyl, or C1-6alk, wherein said phenyl, benzyl, and C1-6alk are substituted by 0, 1, 2 or 3 substituents which are, independently, halo, C1-4alk, C1-3haloalk, —OH, —OC1-4alk, —NH2, —NHC1-4alk, —OC(═O)C1-4alk, or —N(C1-4alk)C1-4alk;
• Rc is C0-4alk-L2;
• each L1 is independently a carbon-linked or nitrogen-linked saturated, partially-saturated or unsaturated 3-, 4-, 5-, 6-, or 7-membered monocyclic ring or a saturated, partially-saturated or unsaturated 6-, 7-, 8-, 9-, 10-, 11-, or 12-membered bicyclic ring, said ring contains 0, 1, 2, 3, or 4 N atoms and 0, 1, or 2 atoms which are O or S;
• L1 is independently substituted by 0, 1, 2 or 3 R9 groups;
• each L2 is independently a carbon-linked or nitrogen-linked saturated, partially-saturated or unsaturated 3-, 4-, 5-, 6-, or 7-membered monocyclic ring or a saturated, partially-saturated or unsaturated 6-, 7-, 8-, 9-, 10-, 11-, or 12-membered bicyclic ring, said ring contains 0, 1, 2, 3, or 4 N atoms and 0, 1, or 2 atoms which are O or S;
• L2 is independently substituted by 0, 1, 2 or 3 R11 groups;
• R8 is halo, CN, OH, OC1-4alk, C1-4alk, C1-4haloalk, OC1-4haloalk, —C(═O)Rb, —C(═O)Rc, —C(═O)NHRb, —C(═O)NHRc, —S(═O)2Rb, —S(═O)2Rc, —S(═O)2NRaRa, Rb, Rc, NO2, ORb, or ORc;
• R9 is halo, C1-6alk, C1-4haloalk, —ORa, —OC1-4haloalk, CN, —C(═O)Rb, —C(═O)ORa, —C(═O)NRaRa, —C(═NRa)NRaRa, —OC(═O)Rb, —OC(═O)NRaRa, —OC1-6alkNRaRa, —OC1-6alkORa, —SRa, —S(═O)Rb, —S(═O)2Rb, —S(═O)2NRaRa, —NRaRa, —N(Ra)C(═O)Rb, —N(Ra)C(═O)ORb, —N(Ra)C(═O)NRaRa, —N(Ra)C(═NRa)NRaRa, —N(Ra)S(═O)2Rb, —N(Ra)S(═O)2NRaRa, —NRaC1-6alkNRaRa, —NRaC1-6alkORa, —C1-6alkNRaRa, —C1-6alkORa, —C1-6alkN(Ra)C(═O)Rb, —C1-6alkOC(═O)Rb, —C1-6alkC(═O)NRaRa, —C1-6alkC(═O)ORa, oxo, or Rc;
• R10 is oxo, C1-6alk, C1-3haloalk, —OH, —OC1-4alk, —NH2, —NHC1-4alk, —OC(═O)C1-4alk, or —N(C1-4alk)C1-4alk;
• and
• R11 is halo, C1-6alk, C1-4haloalk, —ORa, —OC1-4haloalk, CN, —C(═O)Rb, —C(═O)ORa, —C(═O)NRaRa, —C(═NRa)NRaRa, —OC(═O)Rb, —OC(═O)NRaRa, —OC1-6alkNRaRa, —OC1-6alkORa, —SRa, —S(═O)Rb, —S(═O)2Rb, —S(═O)2NRaRa, —NRaRa, —N(Ra)C(═O)Rb, —N(Ra)C(═O)ORb, —N(Ra)C(═O)NRaRa, —N(Ra)C(═NRa)NRaRa, —N(Ra)S(═O)2Rb, —N(Ra)S(═O)2NRaRa, —NRaC1-6alkNRaRa, —NRaC1-6alkORa, —C1-6alkNRaRa, —C1-6alkORa, —C1-6alkN(Ra)C(═O)Rb, —C1-6alkOC(═O)Rb, —C1-6alkC(═O)NRaRa, —C1-6alkC(═O)ORa, or oxo.