Aminosulfur Trifluoride Deoxofluorination
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Aliphatic [18F]Fluorination Chemistry for Positron Emission Tomography Jian Rong and Steven H. Liang Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
Introduction Positron emission tomography (PET) is a noninvasive medical imaging technique that has been rapidly developing in the past several decades. By imaging the uptake and distribution of a radiolabeled molecule, PET is an important diagnostic tool for investigating diverse types of diseases in preclinical and clinical research and drug development. Compared to other imaging techniques, such as magnetic resonance imaging (MRI), computed tomography (CT), X-ray, or ultrasound which provide structural and anatomical information, PET provides quantitative functional information about biological process at the molecular level. Following by in vivo injection of molecules labeled with positron-emitters, PET imaging is accomplished by the detection of two gamma ray photons (511 keV, ~180 apart) from annihilation of a positron (from b+-decay from radiolabeled molecules) and an electron in proximity. Frequently used positron-emitting radionuclides
include carbon-11 (11C, half-life 20.4 min), nitrogen-13 (13N, half-life 10.0 min), oxygen-15 (15O, half-life 2.0 min), fluorine-18 (18F, half-life 109.8 min), as well as radiometals, such as copper-64 (64Cu, half-life 12.7 h), gallium-68 (68Ga, half-life 68 min), yttrium-86 (86Y, halflife 14.7 h), and zirconium-89 (89Zr, half-life 78.4 h). In particular, fluorine-18 has distinct characteristics as positron-emitting radionuclide, such as high positron emission pattern (97% b+-decay ratio), reasonable half-life (109.8 min), which not only allows sufficient time for 18F-incorporation of target molecules and 18F-labeled molecules to reach and bind molecular targets (compared to 11 C), but also provides reduced radiation dosimetry for patients (compared to long-lived radiometals). The relatively low positron energy (0.635 MeV) limits fluorine-18 to short travel path, leading to high-resolution PET images. Nowadays, 18F is the most widely used positronemitting radioisotope probably attributed to the widely used PET pharmaceutical, 2-[18F]fluoro2-deoxy-D-glucose ([18F]FDG) which is used clinically to assess cancers, cardiovascular and neurological diseases. The favorable characteristics of fluorine-18 generate a continuous need to develop novel 18F-labeled PET molecules and related chemical methods for radiofluorination in order to study various disease conditions and conduct thorough investigation of diverse biological process. In this chapter, our focus relies on the review of aliphatic 18F-fluorination chemistry, i.e., Csp3-18F
© Springer Nature Singapore Pte Ltd. 2020 J. Hu, T. Umemoto (eds.), Fluorination, Synthetic Organofluorine Chemistry 1, https://doi.org/10.1007/978-981-10-3896-9
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Aliphatic [18F]Fluorination Chemistry for Positron Emission Tomography
Aliphatic [18F]Fluorination Chemistry for Positron Emission Tomography, F
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