Selective activation of secondary C–H bonds by an iron catalyst: insights into possibilities created by the use of a carboxyl-containing bipyridine ligand
4′-dicarboxylic acid), which could activate the C–H bonds of cycloalkanes with high secondary (2°) C–Hbond selectivity. A turnover number (TN) of 11.8 and a 30% yield (based on the H2O2 oxidant) were achieved during the catalytic oxidation of cyclohexane by 1 under irradiation with visiblelight. For the transformation of cycloalkanes and bicyclic decalins with both 2° and tertiary (3°) C–H bonds, 1 always preferred
在这项工作中,我们报告发现了一种含羧基的铁催化剂1(Fe II -DCBPY,DCBPY = 2,2'-联吡啶-4,4'-二羧酸),该催化剂可以活化环烷烃的C–H键具有较高的次级(2°)CH键选择性。在H2O2的催化氧化过程中达到了11.8的周转数(TN)和30%的收率(基于H 2 O 2氧化剂)。环己烷在可见光照射下,按1。对于具有2°和叔(3°)C–H键的环烷烃和双环十氢化萘的转化,1总是优选将2°C–H键氧化为相应的酮和醇产物;在7个示例中,2°/ 3°的比率介于78/22和> 99/1之间。用18 O同位素标记实验,ESR实验,PPh 3方法和过氧化氢酶方法表征了氧化过程中的反应过程。1的成功表明,除了使用体积较大的催化剂外,使用体积较小的分子铁络合物作为催化剂也可以实现较高的2°C–H键选择性。
Stereoselective oxidation of alkanes with m-CPBA as an oxidant and cobalt complex with isoindole-based ligands as catalysts
作者:Oksana V. Nesterova、Maximilian N. Kopylovich、Dmytro S. Nesterov
DOI:10.1039/c6ra14382b
日期:——
substrates (>98% for cis-1,2-DMCH) and highest cis/trans ratio of tertiary alcohols (products) of 56, under mild conditions. The best achieved yields of tertiary cis-alcohols were of 13.7 and 50.5%, based on the substrate (cis-1,2-DMCH) and the oxidant (m-CPBA) respectively. Kinetic experiments, high bond and stereoselectivity parameters, kinetic isotopeeffect of 7.2(2) in the oxidation of cyclohexane, and
具有通式[M C 6 H 4 C(NH 2)NC(ONCMe 2)2 } 2 ](NO 3)2的异吲哚核配体的两个配合物(M = Co表示1,M = Ni表示2)研究作为催化剂用于与轻度立体选择性氧化烷烃米氯过苯甲酸(米-CPBA)作为氧化剂和顺-1,2-二甲基环己烷(顺式-1,2- DMCH)作为主要模型底物。配合物1表现出显着的活性,并高度保留了底物的立体构型(顺式> 98%-1,2- DMCH)和最高的顺/反式的56(产品),在温和条件下的叔醇的比率。基于底物(顺式-1,2-DMCH)和氧化剂(m -CPBA),最佳的顺式叔醇收率分别为13.7和50.5%。动力学实验,高粘合和立体选择性的参数,在将环己烷氧化的7.2(2)动力学同位素效应,和掺入18从H 2 O 2 18 O支持Co的参与IV ø高价金属-氧中间体作为主要的C -H攻击物种。
Enhancing Chemo- and Stereoselectivity in C–H Bond Oxygenation with H<sub>2</sub>O<sub>2</sub> by Nonheme High-Spin Iron Catalysts: The Role of Lewis Acid and Multimetal Centers
作者:Rahul Dev Jana、Abhishek Das、Tapan Kanti Paine
DOI:10.1021/acs.inorgchem.1c00397
日期:2021.4.19
Spin states of iron often direct the selectivity in oxidation catalysis by iron complexes using hydrogen peroxide (H2O2) on an oxidant. While low-spin iron(III) hydroperoxides display stereoselective C–H bond hydroxylation, the reactions are nonstereoselective with high-spiniron(II) catalysts. The catalytic studies with a series of high-spiniron(II) complexes of N4 ligands with H2O2 and Sc3+ reported
铁的自旋态通常指导铁配合物在氧化剂上使用过氧化氢(H 2 O 2)进行氧化催化的选择性。低旋铁(III)氢过氧化物显示立体选择性C–H键羟基化反应,而高旋铁(II)催化剂的反应非立体选择性。N4配体与H 2 O 2和Sc 3+的一系列高自旋铁(II)配合物的催化研究此处报道的结果表明,路易斯酸具有较高的化学和立体选择性,可促进催化的C–H键羟基化。用含有两个顺式不稳定位点的铁(II)配合物观察到这种反应模式。在Sc 3+的存在下,高自旋铁(II)配合物催化的C–H键羟基化选择性增强,与低自旋铁催化剂的平行。此外,多金属中心的引入增强了铁催化剂的活性和选择性。该研究提供了对过氧化物依赖性生物启发催化剂的开发的见解,该催化剂可选择性地为C–H键进行加氧反应,而无须使用强场配体的铁配合物。
Selective oxygenation of unactivated C–H bonds by dioxygen<i>via</i>the autocatalytic formation of oxoiron(<scp>v</scp>) species
作者:Bittu Chandra、Puja De、Sayam Sen Gupta
DOI:10.1039/d0cc03071f
日期:——
Iron complex catalyzed selective oxygenation of unactivated C–H bonds for a series of substrates by dioxygenviathe autocatalytic formation of oxoiron(v) species is reported.
Alkane oxidation catalysed by a self-folded multi-iron complex
作者:Magi Mettry、Melissa Padilla Moehlig、Adam D. Gill、Richard J. Hooley
DOI:10.1080/10610278.2016.1177184
日期:2017.2.1
electrophilic CH oxidation catalyst. This catalyst oxidises unactivated hydrocarbons including simple, linear alkanes under mild conditions in good yields with selectivity for the oxidation of secondary CH bonds. Control complexes containing a single metal centre are incapable of oxidising unstrained linear hydrocarbons, indicating that participation of multiple centres aids the CH oxidation of challenging