Scheme 2

Conjugation of 13 with its respective chelator and their labelling with ⁶⁴Cu. a (^tBu₃)-NODA-GA, HATU, HOBt, DIPEA, abs. DMF, r.t., 3 h, 46%; b 14a, TFA/CH₂Cl₂/TES/H₂O (20:20:8:7), r.t., 40 h, 44%; c CB-TE2A, HATU, HOBt, DIPEA, abs. DMF, r.t., 5 h, 85%; d glutaric anhydride, DIPEA, abs. DMF, r.t., 16 h, 84%; e 16a, DiAmSar, HATU, HOBt, DIPEA, abs. DMF, r.t., 3 h, 77% for 16 and 9% for 17; f [⁶⁴Cu]CuCl₂, 1 M HEPES (adjusted to pH 4.5 with 1 M HCl), 50 °C, 10 min; g [⁶⁴Cu]CuCl₂, 1 M HEPES (adjusted to pH 4.5 with 1 M HCl), 95 °C, 60 min; h 1 M HEPES, r.t., 10 min