Fibroblast activation protein (fap) inhibitors, fap conjugates, and diagnostic and therapeutic uses thereof

A compound, wherein the compound is of Formula I:

• wherein:
• R1 is Ra;
• R2 and R3 are each Ra or together form a C2-9 heterocycle with the nitrogen atoms to which they are attached;
• R4 is H or an amine protecting group;
• Ra, independently for each occurrence, is selected from H, C1-10 alkyl, C2-10 alkenyl, C3-10 alkynyl, C3-10 cycloalkyl, C6-10 aryl, C2-9 heterocyclyl, or C5-9 heteroaryl, optionally substituted by one or more substituents selected from —OH, —OR′, ═O, ═S, —SH, —SR′, —NH2, —NHR′, —N(R′)2, —NHCOR′, —NR′COR′, halogen, —CN, —CO2H, —CO2R′, —CHO, —COR′, —CONH2, —CONHR′, —CON(R′)2, —NO2, —OP(O)(OH)2, —SO3H, —SO3R′, —SOR′, and —SO2R′, wherein R′, independently for each occurrence, is C1-10 alkyl or C3-10 cycloalkyl;
• n is an integer from 1 to 20;
• and
• m is an integer from 1 to 20;
• or is a pharmaceutically acceptable salt thereof.