One-step synthesis of 18F labeled [18F]-N-succinimidyl 4-(fluoromethyl)benzoate for protein labeling.

[18F]-N-succinimidyl 4-(fluoromethyl)benzoate (1) has been prepared from N-succinimidyl-4-[(4-nitrobenzensulfonyl)oxymethyl]benzoate (2) in one step using Kryptofix 2.2.2/[18F-]. The effect of solvents, potassium salts and temperatures were studied to determine optimum labeling condition. The best results were obtained using carbonate as the counter ion and acetone as the solvent at room temperature. Overall radiochemical yields of approximately 18% (EOS) for the synthesis of 1 were obtained in 30-35 min, including HPLC purification. Proteins were labeled with 1 with labeling yields of 50-70% in 15 min.