Synthesis of N-succinimidyl-4-[18F] fluorobenzoate

The authors have synthesized 18F-labeled prosthetic group, N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) for fluorine-18 labeling peptides and proteins. [18F]SFB seems to be the most suitable 18F-labeling agent because of its higher labeling yield and better stability of the conjugates in vivo. Labeling prosthetic group, triflate salt of ethyl p-trimethylammonium benzoate, was synthesized first, then the radio-synthesis with three steps was carried out, and the first step about 18F-labeling was optimized. After purifying through Sep-Pak C18 cartridge, [18F]SFB was produced with the decay-corrected radiochemical yield of 50% within 1 hour. The radiochemical purity was more than 98% by using radio-TLC and HPLC. (authors)