We 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.