| Project/Area Number |
11670861
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | Tohoku University |
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Principal Investigator |
IWATA Ren Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (60143038)
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| Co-Investigator(Kenkyū-buntansha) |
YANAI Kazuhiko Tohoku University, Graduate School of Medicine, Professor, 大学院・医学系研究科, 教授 (50192787)
IDO Tatsuo Tohoku University, Cyclotron & Radioisotope Center, Professor, サイクロトロン・ラジオアイソトーフセンター, 教授 (80134063)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | PET / Fluorine-18 / Radiopharmaceutical / Labeling precursor / Positron emitter / Fluorobenzyl halide / ポジトロン放出核種 / 標識薬剤合成前駆体 |
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| Research Abstract |
[^<18>F] Fluorobenzyl iodide and bromide ([^<18>F] fluorobenzyl halide) have been expected to be as versatile a precursor for ^<18>F-fluorobenzylation as ^<11>C-labled methyl iodide for ^<11>C-methylation. In the present study, we have aimed at developing a convenient, rapid method for automated preparation of the target compound from [^<18>F] fluoride. Attempts have been made to adapt the following three steps, constituting the synthesis procedure, to on-column processing.
1) Synthesis of [^<18>F] fluorobenzaldehyde from [^<18>F] fluoride : Starting substrates were immobilized on solid-phase-supports and examined for aromatic nucleophilic substitution by [^<18>F] fluoride. However, radiochemical yields of [^<18>F] fluorobenzaldehyde obtained by this method were not high enough for successive reactions. Consequently the on-column method was abandoned.
2) Reduction of [^<18>F] fluorobenzaldehyde into [^<18>F] fluorobenzyl alcohol : Sodium borohydride was chosen among many reductive reagents as it was used in aqueous solutions. While NaBH_4 on alumina gave rather lower yields, a simple on-column method of just flowing a NaBH_4 solution through a C18 cartridge retaining [^<18>F] fluorobenzaldehyde yielded [^<18>F] fluorobenzyl alcohol almost quantitatively. Thus after the reduction [^<18>F] fluorobenzyl alcohol was eluted with CH_2Cl_2.
3) Synthesis of [^<18>F] fluorobenzyl halide from [^<18>F] fluorobenzyl alcohol : Halogenation reagents immobilized to a resin or adsorbed on silica gel were investigated for the reaction. It was observed that radiochemical yields of [^<18>F] fluorobenzyl halide were very dependent on the dryness of the solvent eluting from the C18 cartridge. A semi-automated system was constructed on the basis of the above results and evaluated by preparing new ^<18>F-labeled radioligands from [^<18>F] fluorobenzyl halide.
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