Scheme 2

Radiosynthesis of [¹⁸F]2. Reagents and conditions: (i) K₂CO₃, [¹⁸F/K₂₂₂], DMF, 15 min, 100 °C; (ii) (S)-4-(2-(aminooxy)acetamido)-5-(((S)-1-((S)-2-(((S)-1-methoxy-4-methyl-1-oxopentan-2-yl)carbamoyl)pyrrolidin-1-yl)-3-methyl-1-oxobutan-2-yl)amino)-5-oxopentanoic acid, trifluoroacetic acid (TFA), N,N-dimethylformamide (DMF)/THF, 30 min, 50 °C; (iii) isobutylchloride, N-methylmorpholine, DMF/THF, 5 min, − 10 °C, then CH₂N₂ (0.5 M in Et₂O), 30 min, − 10 °C to rt