The synthesis of some new [4.4]cyclophanediketals, monoketones, and diketones in good yields is reported along with the unusually low reactivity towards hydrolysis of the spiro-1,3-dioxane rings connected to the cyclophane bridges. The structuralanalysis carried out by X-ray diffraction, NMR spectroscopy, and mass spectrometry shows significant intra- and intermolecular π–π and C–H–π interactions
UMSYMMETRICAL BISAZIDES FOR CHEMOSELECTIVE SEQUENTIAL LIGATION
申请人:The Florida State University Research Foundation, Inc.
公开号:US20140018541A1
公开(公告)日:2014-01-16
Unsymmetrical bisazides containing chelating and non-chelating azido groups undergo chemoselective three-component copper(I)-catalyzed azide-alkyne conjugation reactions with two different alkyne molecules. In conjunction with the reactivity gap between aromatic and aliphatic alkynes, a bistriazole molecule can be generated with an excellent regioselectivity by mixing two alkynes and a bisazide in a single reaction container. This method is applicable in aqueous solutions at neutral pH, which may lend utilities in bioconjugation applications.
Effective Modulation of the Donor Properties of N-Heterocyclic Carbene Ligands by “Through-Space” Communication within a Planar Chiral Scaffold
作者:Alois Fürstner、Manuel Alcarazo、Helga Krause、Christian W. Lehmann
DOI:10.1021/ja076028t
日期:2007.10.1
chiral carbene ligands is described, in which an imidazo[1,5-a]pyridine-3-ylidene unit is embedded into a cyclophane scaffold. As evident from the IR data of the corresponding rhodium complex 18 as the parent member of this family, these new ligands turned out to be exceptionallystrong electron donors, rivaling or even outperforming the other diamino-stabilized five-membered N-heterocyclic carbenes
描述了平面手性卡宾配体的高产方法,其中咪唑并 [1,5-a] 吡啶-3-亚基单元嵌入环芳支架中。从作为该家族母体成员的相应铑配合物 18 的 IR 数据可以明显看出,这些新配体是异常强的电子供体,可与其他二氨基稳定的五元 N-杂环卡宾 (NHC ) 迄今已知。然而,如果环芳的远端环被四个氟原子取代,四氟苯部分与下面的卡宾实体之间的空间相互作用会显着降低供体容量。由于 X 射线数据表明氟化和非氟化环芳-2-亚基的空间需求几乎相同,这些结果表明 NHC 配体的电子特性可以在很宽的范围内进行调整,而无需改变其结构或空间属性。合成路线引...
Synthesis of Planar Chiral N-Heterocyclic-Substituted Pyridinophanes
作者:Joshua J. P. Kramer、Martin Nieger、Stefan Bräse
DOI:10.1002/ejoc.201201286
日期:2013.1
ted [2](1,4)benzene[2](2,5)pyridinophanes have been synthesized. With the attached pyrazole, triazole, tetrazole, and pyrimidine moieties, different N,N-chelating ligands that vary in the number of enclosed nitrogen atoms, ring size, and electronic properties were added to a mostly neglected class of pyridinophanes. Additionally, the known synthesis of the pyridinophane scaffold was simplified considerably
Chiroptical properties of dithia[3.3]cyclophanes composed of anthracene and pyridine/pyridinium moieties: A combined experimental and theoretical study
作者:Akinori Shimizu、Keisuke Nagasaki、Yoshihisa Inoue、Tadashi Mori
DOI:10.1002/chir.22740
日期:2017.11
dominated by the local transitions of anthracene. Nevertheless, the CD spectra of 1 and 1‐H+ were well reproduced by theoretical calculations to allow us an unambiguous absolute configuration determination of the first high‐performance liquid chromatography (HPLC) elute (from Chiralcel IB column) as Sp. The transannular interactions between the anthracene and pyridine/pyridinium units were examined by UV‐vis
通过实验和理论研究了中性和质子化[3.3]蒽吡啶并吡啶鎓(1和1 H +)的圆二色性(CD)。引入具有延长的共轭的蒽部分影响了环烷结构,其弯曲角与母体[3.3]吡啶并烷的弯曲角相比明显减小。在观察到的效果棉花(CES)1个乙b频带两者1和1-H +是相当强的,显然bisignate,然而,事实并非是简单的激子对联而是由多个转换。相反,CE在1 L a中要弱得多乐队区域。与母体吡啶吡啶相比,质子化后的光谱变化不那么显着,主要由蒽的局部跃迁控制。然而,1和1 H +的CD谱通过理论计算得到了很好的再现,从而使我们能够明确地确定第一个高效液相色谱(HPLC)洗脱液(来自Chiralcel IB柱)的S p绝对构型。通过紫外可见光谱和荧光光谱检查了蒽与吡啶/吡啶鎓单元之间的跨环相互作用,揭示了低能区的电荷转移(CT)带,特别是对于1 H +。尽管有可比的CT相互作用,但蒽吡啶基吡啶在CT波段的CE