title: Facile aromatic radiofluorination of [18F]flumazenil from diaryliodonium salts with evaluation of their stability and selectivity.
abstract: Aromatic radiofluorination of the diaryliodonium tosylate precursor with [(18)F]fluoride ions has been applied successfully to access [(18)F]flumazenil in high radiochemical yields of 67.2 ± 2.7% (decay corrected). The stability and reactivity of the diaryliodonium tosylate precursor plays a key role in increasing the production of (18)F-labelled molecules under the fluorine-18 labelling condition. Various conditions were explored for the preparation of [(18)F]flumazenil from different diaryliodonium tosylate precursors. Optimum incorporation of [(18)F]fluoride ions in the 4-methylphenyl-mazenil iodonium tosylate precursor (5f) was achieved at 150 °C for 5 min by utilizing 4 mg of the precursor, K(2.2.2)/K(2)CO(3) complex, and the radical scavenger in N,N-dimethylformamide. This approach was extended to a viable method for use in automated synthesis with a radiochemical yield of 63.5 ± 3.2% (decay corrected, n = 26) within 60.0 ± 1.1 min. [(18)F]Flumazenil was isolated by preparative HPLC after the reaction was conducted under improved conditions and exhibited sufficient specific activity of 370-450 GBq μmol(-1), with a radiochemical purity of >99%, which will be suitable for human PET studies.
authors: Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seoul, 110-799, Korea.
authors: Byung Seok
authors: BS
authors: Moon
authors: Hee Seup
authors: HS
authors: Kil
authors: Jun Hyung
authors: JH
authors: Park
authors: Ji Sun
authors: JS
authors: Kim
authors: Jimin
authors: J
authors: Park
authors: Dae Yoon
authors: DY
authors: Chi
authors: Byung Chul
authors: BC
authors: Lee
authors: Sang Eun
authors: SE
authors: Kim
mesh_terms: D005442:Flumazenil / Q000138:chemical synthesis / Q000737:chemistry*; D005462:Fluorine Radioisotopes / Q000737:chemistry; D006847:Hydrocarbons, Iodinated / Q000737:chemistry*; D015394:Molecular Structure; D012492:Salts / Q000737:chemistry
chemical_list: D005462:Fluorine Radioisotopes; D006847:Hydrocarbons, Iodinated; D012492:Salts; D005442:Flumazenil