which have different chirality, and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst. The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiralporphyrin catalysts and the
摘要 通过将 CO2 环加成到环氧化物催化合成环状碳酸酯是固定 的标准方法。为此,设计、制备了手性篮柄卟啉-钴配合物,并通过核磁共振、质谱、傅里叶变换红外光谱、紫外-可见光谱和比旋光度对其进行了充分表征。所提出的金属卟啉催化剂是用具有不同手性的 1,1'-双-2-萘酚或 L-苯丙氨酸合成的,然后应用于环氧丙烷和 的偶联,以在极其温和的条件下生成具有良好对映选择性的手性环状碳酸酯。在四丁基氯化铵作为助催化剂存在的条件下。环加成反应中良好的对映选择性归因于手性卟啉催化剂和底物之间的协同相互作用。讨论了不对称环加成反应的机理和对映选择性。
Hemisquaramide Tweezers as Organocatalysts: Synthesis of Cyclic Carbonates from Epoxides and CO<sub>2</sub>
作者:Kazuto Takaishi、Takafumi Okuyama、Shota Kadosaki、Masanobu Uchiyama、Tadashi Ema
DOI:10.1021/acs.orglett.9b00117
日期:2019.3.1
family of H-bond donor organocatalysts, are reported. The catalysts could be synthesized within two steps. Among them, H8-binaphthyl-linked hemisquaramide 7 markedly accelerated the synthesis of cycliccarbonatesfromepoxides and CO2. The reactions proceeded well under mild and solvent-free conditions. Kinetic resolution was also achieved at −20 °C (s = 3.0). The adjustable bite angle and orientation
Synthesis and a Catalytic Study of Diastereomeric Cationic Chiral-at-Cobalt Complexes Based on (<i>R</i>,<i>R</i>)-1,2-Diphenylethylenediamine
作者:Mikhail A. Emelyanov、Nadezhda V. Stoletova、Alexander F. Smol’yakov、Mikhail M. Il’in、Victor I. Maleev、Vladimir A. Larionov
DOI:10.1021/acs.inorgchem.1c00855
日期:2021.9.20
Here we report the first synthesis of two diastereomeric cationic octahedral Co(III) complexes based on commercially available (R,R)-1,2-diphenylethylenediamine and salicylaldehyde. Both diastereoisomers with opposite chiralities at the metal center (Λ and Δ configurations) were prepared. The new Co(III) complexes possessed both acidic hydrogen-bond donating (HBD) NH moieties and nucleophilic counteranions
在这里,我们报告了基于市售 ( R , R )-1,2-二苯基乙二胺和水杨醛的两种非对映体阳离子八面体 Co(III) 配合物的首次合成。制备了在金属中心具有相反手性的两种非对映异构体(Λ 和 Δ 构型)。新的 Co(III) 配合物同时具有酸性氢键供体 (HBD) NH 部分和亲核抗衡阴离子,并作为双功能手性催化剂通过在温和条件下与 CO 2反应来解决具有挑战性的末端环氧化物和双取代环氧化物的动力学拆分。反式的最高选择性因子 ( s ) 为 2.8-查尔酮环氧化物是在氯苯中以低催化剂负载量(2 mol%)实现的,这是目前此类底物的最佳结果。
Highly regio- and stereoselective synthesis of cyclic carbonates from biomass-derived polyols<i>via</i>organocatalytic cascade reaction
作者:Hui Zhou、Hui Zhang、Sen Mu、Wen-Zhen Zhang、Wei-Min Ren、Xiao-Bing Lu
DOI:10.1039/c9gc03013a
日期:——
The cascade reaction of CO2, vicinal diols, and propargylicalcohol, was firstly achieved by dual Lewis base (LB) organocatalytic systems involving LB–CO2 adducts and commercially available organic amines. This methodology could overcome the chemical inertness of CO2, providing an alternative route to various functionalized five-membered cyclic carbonates in moderate to high yields under mild reaction
CO 2,邻二醇和炔丙醇的级联反应首先通过双路易斯碱(LB)有机催化体系实现,该体系涉及LB–CO 2加合物和可商购的有机胺。该方法可以克服CO 2的化学惰性,在温和的反应条件下(25°C,1.0 atm CO 2)以中等至高收率提供各种功能化的五元环状碳酸酯的替代路线)。更重要的是,该方法还可以用于由生物质衍生的多元醇轻松有效地合成手性多环碳酸酯,并完全保留手性中心的构型。这项研究为构建具有多功能基团和手性中心的增值环状碳酸酯提供了一种环境友好,可扩展且具有成本效益的方案。
Bifunctional phase-transfer catalysts for fixation of CO<sub>2</sub> with epoxides under ambient pressure
作者:Yue-Dan Li、Dong-Xiao Cui、Jun-Chao Zhu、Ping Huang、Zhuang Tian、Yan-Yan Jia、Ping-An Wang
DOI:10.1039/c9gc02058f
日期:——
A series of bifunctional phase-transfercatalysts with a quaternary onium center and a hydrogen-bonding donor group were prepared for the fixation of CO2 with commercially available epoxides under mild conditions by using a CO2 balloon (1 atm). In the presence of 2.5 mol% of achiral bifunctional phase-transfercatalysts, cyclic carbonates were obtained in good to excellent yields (up to 95%). Additionally