Coelenterazine analogues

A compound of formula (II)

• or a tautomer or a salt thereof, wherein:
• Y is nitro, or —NRy1Ry2;
• p is 0, 1, 2, 3, or 4;
• q is 0, 1, 2, 3, 4, or 5;
• p+q is 1, 2, 3, 4, 5, 6, 7, 8, or 9;
• R3, at each occurrence, is independently halogen, CN, nitro, C1-10alkyl, C1-10haloalkyl, —ORA3, or —NRB3RC3;
• R4, at each occurrence, is independently halogen, CN, nitro, C1-10alkyl, C1-10haloalkyl, —ORA4, or —NRB4RC4;
• RA3 and RA4, at each occurrence, are independently H, C1-10haloalkyl, C3-12cycloalkyl, —C(O)C1-10alkyl, —C(O)C3-12cycloalkyl, or —C(O)C1-3alkylene-C3-12cycloalkyl, wherein each cycloalkyl is optionally substituted with 1-4 substituents independently selected from the group consisting of halogen, C1-4alkyl, and C1-4haloalkyl;
• RB3, RB4, RC3, and RC4, at each occurrence, are independently H, C1-10haloalkyl, C3-12cycloalkyl, —C(O)C1-10alkyl, —C(O)C3-12cycloalkyl, —C(O)C1-3alkylene-C3-12cycloalkyl, —SO2C1-10alkyl, —SO2C3-12cycloalkyl, or —SO2C1-3alkylene-C3-12cycloalkyl, wherein each cycloalkyl is optionally substituted with 1-4 substituents independently selected from the group consisting of halogen, C1-4alkyl, and C1-4haloalkyl;
• alternatively, RB3 and RC3 and/or RB4 and RC4, together with the nitrogen atom to which each attaches form a 4- to 8-membered saturated or partially unsaturated heterocyclic ring, optionally substituted with 1-4 substituents independently selected from the group consisting of C1-4alkyl, C1-4haloalkyl, oxo, —OH, and —OC1-4alkyl;
• Ry1 and Ry2, at each occurrence, are independently H, C1-10alkyl, C1-10haloalkyl, C3-12cycloalkyl, or —C1-3alkylene-C3-12cycloalkyl, wherein each cycloalkyl is optionally substituted with 1-4 substituents independently selected from the group consisting of halogen, C1-4alkyl, and C1-4haloalkyl;
• and
• alternatively, Ry1 and Ry2 together with the nitrogen atom to which each attaches form a 4- to 8-membered saturated or partially unsaturated heterocyclic ring, optionally substituted with 1-4 substituents independently selected from the group consisting of C1-4alkyl, C1-4haloalkyl, oxo, —OH, and —OC1-4alkyl.