Nonsense mediated decay inhibitor compounds

A compound having formula (V):

• or a pharmaceutically acceptable salt thereof;
• wherein:
• ring D is
• phenyl;
• heteroaryl of 5-6 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(R7), O, and S;
• and wherein R7 is H, C1-3 alkyl, or —C(O)C1-3 alkyl;
• or
• heterocyclyl or heterocycloalkenyl of 4-7 ring atoms, wherein from 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(R7), O, and S;
• and wherein R7 is H, C1-3 alkyl, or —C(O)C1-3 alkyl;
• X is H, —F, Cl, C1-C4 alkyl, or CN;
• A is —SO2NR1R2, —C(O)NR1R2, —SO3H, —SO2RA, or —PO(OH)2;
• RA is C1-6 alkyl, which is optionally substituted with 1-3 substituents independently selected from the group consisting of:
• —OH, C1-4 alkoxy, C1-4 haloalkoxy, and F;
• each occurrence of R1 and R2 is independently selected from the group consisting of:
• H and C1-6 alkyl, wherein the C1-6 alkyl is optionally substituted with 1-3 substituents independently selected from the group consisting of:
• —CO2H;
• —CO2(C1-4 alkyl);
• —OC(O)(CH2)n—CO2H, wherein n is 1-4 (e.g., n is 2);
• —OC(O)(CH2)n—CO2(C1-4 alkyl), wherein n is 1-4 (e.g., n is 2);
• —OH;
• C1-4 alkoxy;
• C1-4 haloalkoxy;
• —F, and
• —NR′R″, wherein each of R′ and R′ is independently selected from the group consisting of H and C1-4 alkyl;
• or
• R1 and R2, taken together with the nitrogen atom connecting them, forms a saturated, partially unsaturated, or aromatic ring including 4-8 ring atoms, wherein from 0-2 ring atoms (in addition to the nitrogen atom connecting R1 and R2) are ring heteroatoms each independently selected from the group consisting of N, N(R7), O, and S;
• and wherein the ring is optionally substituted with 1-4 independently selected Ra;
• wherein R7 is H, C1-6 alkyl, or —C(O)C1-6 alkyl;
• each of rings A, B, and C is independently and optionally substituted with 1-3 independently selected Ra;
• each occurrence of R3 and R4 is independently selected from the group consisting of:
• H and C1-3 alkyl;
• each occurrence of R5 and R6 is independently selected from the group consisting of:
• H and C1-6 alkyl,
• Y is O or S;
• each occurrence of Ra is independently selected from the group consisting of halo, C1-6 alkyl, C1-6 haloalkyl, cyano, C1-6 alkoxy, C1-6 haloalkoxy, C1-6 thioalkoxy, C1-6 halothioalkoxy, S(O)2(C1-6 alkyl), C3-6 cycloalkyl, C6-10 aryl, NR8R9, C(O)R8, and C(O)NR8R9, and
• each occurrence of R8 and R9 is independently selected from the group consisting of H and C1-3 alkyl.