and their reduced diamine counterparts 3b,3d–3g and 3i form complexes 4a–4i, 5b,5d–5g, and 5i with PdCl2 in DMF or methanol. Using 1 mol-% of the isolated complexes 4e and 5f many polychlorinated biphenyls (PCBs) can be prepared in moderate to excellent yields according to the Suzuki crosscoupling protocol with contact to air. Several 4-acetylbiphen
Nickel-Catalyzed Asymmetric <i>C</i>-Alkylation of Nitroalkanes: Synthesis of Enantioenriched β-Nitroamides
作者:Vijayarajan Devannah、Rajgopal Sharma、Donald A. Watson
DOI:10.1021/jacs.9b04175
日期:2019.5.29
A general catalytic method for asymmetric C-alkylation of nitroalkanes using nickel catalysis is described. This method enables the formation of highly enantioenriched β-nitroamides from readily available α-bromoamides using mild reaction conditions that are compatible with a wide range of functional groups. When combined with subsequent reactions, this method allows access to highly enantioenriched
Machine‐Assisted Preparation of a Chiral Diamine Ligand Library and In Silico Screening Using Ab Initio Structural Parameters for Heterogeneous Chiral Catalysts
containing 31 chiral diamines was synthesized using a flow-based semiautomatic reductiveaminationsystem. These ligands were evaluated in a continuous-flow asymmetric 1,4-addition reaction with a heterogeneous Ni catalyst. Based on the experimental results of ab initio DFT calculations, a prediction model for enantioselectivities was successfully constructed. Furthermore, virtual screening of possible ligands
使用基于流动的半自动还原胺化系统合成了包含 31 个手性二胺的配体库。这些配体在与非均相 Ni 催化剂的连续流动不对称 1,4-加成反应中进行了评估。基于 ab initio DFT 计算的实验结果,成功构建了对映选择性的预测模型。此外,对可能的配体进行虚拟筛选以鉴定有希望的结构,其在实验中显示出良好的对映选择性。
Unravelling Structural Dynamics, Supramolecular Behavior, and Chiroptical Properties of Enantiomerically Pure Macrocyclic Tertiary Ureas and Thioureas
circular dichroism of thioureas is controlled by the chiral neighborhood closest to the chromophore. The dynamically induced exciton couplet is observed when the biphenyl chromophores are present in the macrocycle core. In the solid state, the seemingly disordered molecules may create ordered networks stabilized by intermolecular S···halogen, H···halogen, and S···H interactions. The presence of two bromine
将尿素或硫脲功能引入大环骨架代表了一种控制图形周期结构的手性多胺构象动力学的替代方法。形式上高度对称,这些大环化合物可以适应不同的构象,这取决于酰胺接头的性质和芳族单元内的取代模式。存在于大环核心每个顶点的 N–C(═X)–N 单元中杂原子 X 的类型构成了决定手性光学性质的主要因素。与含尿素的衍生物相比,硫脲的电子圆二色性受最靠近生色团的手性邻域控制。当联苯发色团存在于大环核中时,观察到动态诱导的激子对。在固态,看似无序的分子可能会产生由分子间 S···卤素、H···卤素和 S···H 相互作用稳定的有序网络。硫脲衍生的三角胺中每个芳族单元中存在两个溴取代基会在晶体中产生自分类现象。在溶液中,这种特殊的大环化合物作为两种构象非对映异构体的动态等摩尔混合物存在,不同之处在于 C-Br 键的空间(顺时针和逆时针)排列。在晶格中,给定手性的大环组装成同螺旋层。硫脲衍生的三角胺中每个芳族单元中存
Synthesis and characterisation of Cu(II) complexes bearing N,N′-di(methoxybenzyl)-(R,R)-1,2-diaminocyclohexane as catalysts for the asymmetric nitroaldol reaction
作者:Sang Eun Song、Quang Trung Nguyen、Jeong Jae Yu、Hong-In Lee、Jong Hwa Jeong
DOI:10.1016/j.poly.2013.09.006
日期:2014.1
Enantiopure Cu(II) complexes with N,N'-di(p-methoxybenzyl)-(R,R)-1,2-diaminocyclohexane (L-1), 101'di(m-methoxybenzy1)-(R,R)-1,2-diaminocyclohexane (L-2), and N,N'-di(m-methoxybenzyI)-(R,R)-1.2diaminocyclohexane (L-3) ligands were synthesised and characterised. The X-ray crystal structures of Cu(II) complexes containing 1.1 and L3 were determined. The geometry around the Cu(II) centre for (L-1)CuCl2 was distorted square-planar. The crystal structure of (L-3)CuCl2 revealed a square-pyramidal structure with a strong interaction between the Cu and O of the methoxy group. Their double catalytic activation with diisopropylethylamine in the asymmetric nitroaldol reaction of benzaldehyde and nitromethane was examined. The reaction yield was moderate with an enantiomeric excess of up to 87%. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.