Asymmetric Synthesis of All-Carbon Benzylic Quaternary Stereocenters via Conjugate Addition to Alkylidene and Indenylidene Meldrum’s Acids
作者:Ashraf Wilsily、Eric Fillion
DOI:10.1021/jo901559d
日期:2009.11.20
aryl group consistently leading to high enantioselectivities. The nature of the organozinc reagent on the efficiency and selectivity of the conjugateaddition was also investigated. The solid-state conformation was determined for a number of alkylidene Meldrum’s acids and correlated with the observed enantioselectivity in relation to the arene pattern of substitution.
A process for fluorination of aromatic compounds employing iodonium ylides and applicable to radiofluorination using 18F is described. Processes, intermediates, reagents and radiolabelled compounds are described.
The nucleophilic 211At-labeling of aryliodoniumylides was investigated and proved significantly more efficient than radioiodination. Reaction is rapid at room temperature with electron-poor activated substrates whereas heating and addition of the radical scavenger TEMPO was essential in the case of deactivated precursors to reach high RCY and molar activity.
研究了芳基碘鎓叶立德的亲核 211 At 标记,并证明比放射性碘标记更有效。在室温下与贫电子活化底物反应迅速,而在失活前体达到高 RCY 和摩尔活性的情况下,加热和添加自由基清除剂 TEMPO 是必不可少的。
Improved synthesis of 4-[<sup>18</sup>
F]fluoro-<i>m</i>
-hydroxyphenethylguanidine using an iodonium ylide precursor
作者:Yong-Woon Jung、Guie Gu、David M. Raffel
DOI:10.1002/jlcr.3791
日期:2019.10
Fluorine-18 labeled hydroxyphenethylguanidines were recently developed in our laboratory as a new class of PET radiopharmaceuticals for quantifying regional cardiac sympathetic nerve density in heart disease patients. Studies of 4-[18F]fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG) and 3-[18F]fluoro-p-hydroxyphenethylguanidine ([18F]3F-PHPG) in human subjects have shown that these radiotracers can be used to generate high-resolution maps of regional sympathetic nerve density using the Patlak graphical method. Previously, these compounds were synthesized using iodonium salt precursors, which provided sufficient radiochemical yields for on-site clinical PET studies. However, we were interested in exploring new methods that could offer significantly higher radiochemical yields. Spirocyclic iodonium ylide precursors have recently been established as an attractive new approach to radiofluorination of electron-rich aromatic compounds, offering several advantages over iodonium salt precursors. The goal of this study was to prepare a spirocyclic iodonium ylide precursor for synthesizing [18F]4F-MHPG and evaluate its efficacy in production of this radiopharmaceutical. Under optimized automated reaction conditions, the iodonium ylide precursor provided radiochemical yields averaging 7.8% ± 1.4% (n = 8, EOS, not decay corrected), around threefold higher than those achieved previously using an iodonium salt precursor. With further optimization and scale-up, this approach could potentially support commercial distribution of [18F]4F-MHPG to PET centers without on-site radiochemistry facilities.
Synthesis and Preliminary Evaluations of a Triazole-Cored Antagonist as a PET Imaging Probe ([<sup>18</sup>F]N2B-0518) for GluN2B Subunit in the Brain
作者:Hualong Fu、Weiting Tang、Zhen Chen、Vasily V. Belov、Genwei Zhang、Tuo Shao、Xiaofei Zhang、Qingzhen Yu、Jian Rong、Xiaoyun Deng、Wei Han、Scott J. Myers、Pilar Giffenig、Lu Wang、Lee Josephson、Yihan Shao、April T. Davenport、James B. Daunais、Mikhail Papisov、Hongjie Yuan、Zijing Li、Stephen F. Traynelis、Steven H. Liang
DOI:10.1021/acschemneuro.8b00591
日期:2019.5.15
emission tomography (PET) studies of GluN2B-selective NMDARs in the living brain would enable target engagement in drug development and improve our understanding in the NMDAR signaling pathways between normal and disease conditions, a suitable PET ligand is yet to be identified. Herein we developed an 18F-labeled potent antagonist, 2-((1-(4-[18F]fluoro-3-methylphenyl)-1 H-1,2,3-triazol-4-yl)methoxy)-5-methoxypyrimidine