Luciferin Amides

A compound of formula (I):

• wherein
• n is 0 or 1;
• is deleted, a single bond, or a double bond;
• provided that, when n is 0, is deleted;
• each of X1 and X2, independently, is O, S, Se, N, N(Ra), C(Ra), or C(RaRa′), in which each of Ra and Ra′, independently, is H or C1-C10 alkyl;
• provided that, when is a double bond, X1 is N or C(Ra);
• each of Y1 and Y2, independently, is N or C(Rb), in which Rb is H or C1-C10 alkyl;
• Z is C(Rc) or C(RcRc′), in which each of Rc and Re, independently, is H or C1-C10 alkyl;
• provided that, when is a single bond, Z is C(RcRc′) and that, when is a double bond, Z is C(Rc);
• R2 is H, N(RdRd′), or ORd, in which each of Rd and Rd′, independently, is H, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C20 cycloalkyl, C3-C20 cycloalkenyl, C1-C20 heterocycloalkyl, C1-C20 heterocycloalkenyl, aryl, or heteroaryl;
• each of R1, R3, R4, R5, and R6, independently, is H, halo, CN, ORe, SRe, NO2, N(ReRe′), C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C20 cycloalkyl, C3-C20 cycloalkenyl, C1-C20 heterocycloalkyl, C1-C20 heterocycloalkenyl, aryl, heteroaryl, in which each of Re and Re′, independently, is H or C1-C10 alkyl;
• or R1 and R2, together with the carbon atoms to which they are attached, are a substituted or unsubstituted 5, 6, or 7-membered ring optionally fused with one or more substituted or unsubstituted 5, 6, or 7-membered rings;
• or R2 and R3, together with the carbon atoms to which they are attached, are a substituted or unsubstituted 5, 6, or 7-membered ring optionally fused with one or more substituted or unsubstituted 5, 6, or 7-membered rings;
• and
• each of R7 and R8, independently, is H, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C20 cycloalkyl, C3-C20 cycloalkenyl, C1-C20 heterocycloalkyl, C1-C20 heterocycloalkenyl, aryl, or heteroaryl.