O-(2-18F-Fluoroethyl)-L-tyrosine (FET) and O-(3-18F-fluoropropyl)-L-tyrosine (FPT) were prepared by a two-step reaction. First
nucleophilic fluorination reaction of 18F-fluoride with 1
2-di (4-methylphenylsulfonyloxy) ethane (TsOCH2CH2OTs) and 1
3-di(4-methylphenylsulfonyloxy) propane (TsOCH2CH2CH2OTs) gave 2-18F-1-(4- methylphenylsulfonyloxy) ethane (18FCH2CH2OTs) and 3-18F-1-(4-methylphenylsulfonyloxy) propane (18FCH2CH2CH2 OTs)
respectively. Then
18F-fluoroalkylation of L-tyrosine di-sodium salt formed FET and FPT respectively
with the whole synthesis time of less than 90 min. Purification of resultant FET and FPT by acetonitrile precipitation gave an overall radiochemical yield of 4.7% and 8% with no decay correction
and purification by HPLC gave an overall radiochemical yield of 20% and 30% with no decay correction
respectively. The radiochemical purity of FET and FPT injection was above 95%
and all quality parameters met the quality requirements of radiopharmaceuticals.