Compounds and probes for imaging huntingtin protein

A compound of Formula (I):

• or an isotopically labeled analog, pharmaceutically acceptable salt, solvate, stereoisomer, or mixture of stereoisomers thereof,
• wherein:
• Z1 and Z2 are each independently CH, or one of Z1 and Z2 is N and the other is CH;
• Z3 is N or CH;
• L1 is —O—C1-4 alkylene;
• one of X1 and X2 is N-L2-R2 and the other is CH2;
• X3 is CH2 or —O—CH2—;
• L2 is —C(═O)—;
• R1 is heteroaryl optionally substituted with one or two substituents independently selected from hydroxy, alkyl, alkoxy, haloalkoxy, and —N(R4)2;
• R2 is aryl, heteroaryl, heterocycloalkyl, or heterocycloalkenyl, each of which is substituted with one or two substituents independently selected from halogen, haloalkyl, hydroxy, alkyl, alkoxy, haloalkoxy, heteroaryl, and —N(R4)2;
• wherein when R2 is substituted with alkyl, the alkyl is optionally substituted with alkenyl or alkoxy;
• wherein when R2 is substituted with alkoxy, the alkoxy is optionally substituted with alkenyl or alkoxy;
• p is 0, 1, or 2;
• each R3 is independently C1-4 alkyl;
• and
• each R4 is independently H or C1-4alkyl.