Synthesis of a F-18 labeled analog of antitumor prostaglandin delta 7-PGA1 methyl ester using p-[18F]fluorobenzylamine.

A fluorine-18 labeled analog of an antitumor prostaglandin delta 7-PGA1 methyl ester, 15-deoxy-13,14-dihydro-delta 7-PGA1 4-[18F]fluorobenzyl amide ([18F]3), was synthesized as a tracer candidate for detecting tumors with positron emission tomography. p-[18F]Fluorobenzylamine (p-[18F]FBnA) used as a labeled precursor for the synthesis of [18F]3 was prepared by fluorination of a 4-N, N, N-trimethylammonium-benzonitrile triflate with [18F]fluoride and subsequent reduction with borane-dimethylsulfide. Radiochemical yield and purity of p-[18F]FBnA obtained were 39-49% (decay uncorrected) and 91-96%, respectively, after C18 Sep-Pak purification. Treatment of p-[18F]FBnA with a 15-deoxy-13,14-dihydro-delta 7-PGA1 N-succinimidyl ester in acetonitrile and subsequent HPLC purification gave radiochemically pure (> 99%) [18F]3 with a 58% decay uncorrected yield. The total synthesis time was 70 min from the start of the radiosynthesis of p-[18F]FBnA.