Joong-Hyun Chun, Pike Victor W
[ ] Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health 10 Center Drive, Building 10, Room B3 C346A, Bethesda, MD 20892, USA.
European J Org Chem. 2012 Aug 1;2012(24):4541-4547. doi: 10.1002/ejoc.201200695.
Positron emission tomography (PET) is an increasingly important biomedical imaging technique that relies on the development of radiotracers labeled with positron-emitters to achieve biochemical specificity. Fluorine-18 ( = 109.7 min) is an attractive positron-emitting radiolabel for organic radiotracers, primarily because of its longer half-life and greater availability relative to those for the main alternative, carbon-11 ( = 20.4 min). Rapid simple methods are sought for labeling prospective PET radiotracers with fluorine-18 from cyclotron-produced aqueous [F]fluoride ion, which must often be converted first into a suitably reactive labeling synthon for use in a subsequent labelling reaction. Use of F-labeled synthons in 'click chemistry' attracts increasing attention for labeling PE Tradiotracers. Here we describe rapid single-step radiosyntheses of azido- or azidomethyl-bearing [F]fluoroarenes from the reactions of diaryliodonium salts with no-carrier-added [F]fluoride ion within a microfluidic apparatus to provide previously poorly accessible F-labeled click synthons in radiochemical yields of 15% for [F]4-fluorophenyl azide and about 40% for each of the F-fluorobenzenes. The radiosyntheses of the latter synthons was possible under 'wet conditions', so obviating the need to dry the cyclotron-produced [F]fluoride ion and greatly enhancing the practicality of the method.
正电子发射断层扫描（PET）是一种日益重要的生物医学成像技术，它依赖于开发用正电子发射体标记的放射性示踪剂来实现生化特异性。氟-18（半衰期 = 109.7分钟）是有机放射性示踪剂中一种有吸引力的正电子发射放射性标记物，主要是因为相对于主要替代物碳-11（半衰期 = 20.4分钟），它具有更长的半衰期和更高的可得性。人们正在寻找快速简便的方法，用回旋加速器产生的含水[F]氟离子对预期的PET放射性示踪剂进行氟-18标记，而这种离子通常必须先转化为一种合适的活性标记合成子，以便用于后续的标记反应。在“点击化学”中使用F标记的合成子在标记PET放射性示踪剂方面越来越受到关注。在此，我们描述了在微流控装置中，通过二芳基碘鎓盐与无载体添加的[F]氟离子反应，快速一步法合成含叠氮基或叠氮甲基的[F]氟芳烃，以提供以前难以获得的F标记点击合成子，[F]4-氟苯基叠氮的放射化学产率为15%，每种[F]（叠氮甲基）-氟苯的放射化学产率约为40%。后一种合成子的放射合成可以在“湿条件”下进行，因此无需干燥回旋加速器产生的[F]氟离子，大大提高了该方法的实用性。
