聚集的 tau 蛋白是存在于几种神经退行性疾病中的核心病理学。因此,选择性结合原纤维形式聚集的 tau 的正电子发射断层扫描 (PET) 成像放射性示踪剂的开发和应用对于进一步了解这些疾病具有重要意义。虽然用于人类 PET 研究的放射性示踪剂提供了宝贵的见解,但也能够在动物模型中可视化 tau 原纤维的放射性示踪剂是对这些疾病进行转化研究的重要工具。在此,我们报告了基于为该应用开发的苯基/吡啶基丁二烯基苯并噻唑/苯并噻唑 (PBB3) 骨架的新型化合物库的合成和表征。从这个库中,我们选择了化合物 LM229,它以高亲和力与重组 tau 原纤维结合(K d = 3.6 nM) 并以高特异性检测 (a) 来自转基因人类 P301S tau 小鼠的活培养神经元和小鼠脑切片中的病理 4R tau 聚集体,(b) 截短的人类 151-351 3R (SHR24) 和 4R (SHR72)转基因大鼠脑切片中的
Flexible, dicationic imidazolium salts for<i>in situ</i>application in palladium-catalysed Mizoroki-Heck coupling of acrylates under aerobic conditions
作者:Marilyn Daisy Milton、Parul Garg
DOI:10.1002/aoc.3503
日期:2016.9
incorporating the features of both bidentate chelating O,O ligand and carbene, shows the maximum catalytic activity. A variety of aryl and heteroaryl methyl and ethyl cinnamates were synthesized using these imidazolium salts as preligands. In addition, NMRstudies confirm in situ generation of normal N‐heterocyclic carbenes from the C‐2 position of imidazol‐2‐ylidene ring. The mercury poisoning test was also
Water is demonstrated to be an excellent medium for the Wittigreaction employing stabilized ylides and aldehydes. Although the solubility in water appears to be an unimportant characteristic in achieving good chemical yields and E/Z-ratios, the rate of Wittigreactions in water is unexpectedly accelerated.
Chiral Magnesium(II) Binaphtholates as Cooperative Brønsted/Lewis Acid-Base Catalysts for the Highly Enantioselective Addition of Phosphorus Nucleophiles to α,β-Unsaturated Esters and Ketones
作者:Manabu Hatano、Takahiro Horibe、Kazuaki Ishihara
DOI:10.1002/anie.201300938
日期:2013.4.22
cooperative Brønsted/Lewis acid–base supramolecular catalysts formed in situ from simple chiral magnesium(II) binaphtholate aqua complexes promoted the highly enantioselective 1,4‐hydrophosphinylation of α,β‐unsaturated esters with diaryl phosphine oxides and 1,2‐hydrophosphonylation of α,β‐unsaturatedketones with dialkyl phosphites (see scheme).
An effective protocol was developed for the Heck coupling reactions between various aryl halides and olefins. In the presence of 2 mol% of Pd(OAc) 2 , the desired products could be obtained in good yields under ligand-free and aerobic conditions. The catalytic system could be easily recycled for five times with high efficiency.
Probing the Evolution of Palladium Species in Pd@MOF Catalysts during the Heck Coupling Reaction: An Operando X-ray Absorption Spectroscopy Study
作者:Ning Yuan、Vlad Pascanu、Zhehao Huang、Alejandro Valiente、Niclas Heidenreich、Sebastian Leubner、A. Ken Inge、Jakob Gaar、Norbert Stock、Ingmar Persson、Belén Martín-Matute、Xiaodong Zou
DOI:10.1021/jacs.8b03505
日期:2018.7.5
mechanism of the Heck C-C coupling reactioncatalyzed by Pd@MOFs has been investigatedusing operando X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) combined with transmission electron microscopy (TEM) analysis and nuclear magnetic resonance (1H NMR) kinetic studies. A custom-made reaction cell was used, allowing operando PXRD and XAS data collection using high-energy synchrotron
使用原位 X 射线吸收光谱 (XAS) 和粉末 X 射线衍射 (PXRD) 结合透射电子显微镜 (TEM) 分析和核磁共振 (1H) 研究了由 Pd@MOFs 催化的 Heck CC 偶联反应的机理。 NMR)动力学研究。使用定制的反应池,允许使用高能同步辐射进行操作 PXRD 和 XAS 数据收集。通过结合非原位研究分析 XAS 数据,可以跟踪钯物种从合成状态到失活形式的演变。提出了一种自适应反应机制。发现单核 Pd(II) 配合物是反应开始时的主要活性物质,然后在随后的催化转换中逐渐转变为平均具有 13-20 个 Pd 原子的 Pd 纳米团簇。可用试剂和底物的消耗导致 Cl- 离子与其表面配位,从而导致活性位点中毒。通过了解失活过程,可以调整反应条件并延长催化剂的寿命。