Iron Catalyzed Double Bond Isomerization: Evidence for an Fe
<sup>I</sup>
/Fe
<sup>III</sup>
Catalytic Cycle
作者:Callum R. Woof、Derek J. Durand、Natalie Fey、Emma Richards、Ruth L. Webster
DOI:10.1002/chem.202004980
日期:2021.4
Density Functional Theory (DFT) and Electron Paramagnetic Resonance (EPR) spectroscopy. The data obtained support a pre‐catalyst activation step that gives access to an η2‐coordinated alkene FeI complex, followed by oxidative addition of the alkene to give an FeIII intermediate, which then undergoes reductive elimination to allow release of the isomerization product.
据报道,铁催化的烯烃异构化使用铁(II) β-二酮亚胺预催化剂。该反应在催化量的氢化物源(例如频哪醇硼烷(HBpin)或氨硼烷(H 3 N·BH 3))下进行。已研究了与烯丙基芳烃和脂肪族烯烃的反应性。通过多种手段研究了催化机理,包括氘化研究、密度泛函理论(DFT)和电子顺磁共振(EPR)光谱。获得的数据支持预催化剂活化步骤,该步骤提供了 η 2配位烯烃 Fe I络合物,然后通过氧化加成烯烃得到 Fe III中间体,然后进行还原消除以释放异构化产物。
Nitrogen-Doped Carbon-Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration in Allylarenes
homogeneous catalysts. In contrast, very limited progress has been made with the use of cheap, Earth‐abundant base metals as heterogeneous catalysts for these transformations—in spite of the obvious economic and environmental advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular, for allylarenes. The catalyst material
Enantio- and Regioselective Ni-Catalyzed <i>para</i>-C–H Alkylation of Pyridines with Styrenes via Intermolecular Hydroarylation
作者:Jun-Bao Ma、Xia Zhao、Dongju Zhang、Shi-Liang Shi
DOI:10.1021/jacs.2c04043
日期:2022.8.3
pyridines through the use of a Ni–Al bimetallic catalyst system and N-heterocyclic carbene (NHC) ligand for intermolecular hydroarylation of styrenes. The reaction procceds in high to excellent enantioselectivities (up to 98.5:1.5 er) and high site-selectivities for both styrene and pyridine components (up to >98:2). Consequently, a broad range of enantioenriched 1,1-diarylalkanes containing pyridine
B(C
<sub>6</sub>
F
<sub>5</sub>
)
<sub>3</sub>
‐Catalyzed
<i>E</i>
‐Selective Isomerization of Alkenes
作者:Betty A. Kustiana、Salma A. Elsherbeni、Thomas G. Linford‐Wood、Rebecca L. Melen、Matthew N. Grayson、Louis C. Morrill
DOI:10.1002/chem.202202454
日期:2022.11.11
report the B(C6F5)3-catalyzed E-selective isomerization of alkenes. The transition-metal-free method is applicable across a diverse array of readily accessible substrates, accessing a broad range of synthetically useful products containing versatile stereodefined internal alkenes. Synthetic and computational mechanistic studies indicate that the isomerization proceeds along competing 1,2-hydride shift
Move along !:在此,我们报道了 B(C 6 F 5 ) 3 -催化的E -烯烃选择性异构化。不含过渡金属的方法适用于各种易于获得的底物,可获得范围广泛的合成有用产品,其中包含多功能立体定义的内部烯烃。合成和计算机理研究表明,异构化沿着竞争性 1,2-氢化物转移和氢化物提取途径进行。
Enhanced Turnover for the P450 119 Peroxygenase-Catalyzed Asymmetric Epoxidation of Styrenes by Random Mutagenesis
作者:Li Wang、Siping Wei、Xianchao Pan、Pingxian Liu、Xi Du、Chun Zhang、Lin Pu、Qin Wang
DOI:10.1002/chem.201705460
日期:2018.2.21
reduced CO difference spectra and epoxidation of styrene. By using directed evolution, a new CYP119 quadruple mutant S148P/I161T/K199E/T214V is constructed, expressed, and purified. This quadruple mutant significantly increases the turnover rate and conversion for the asymmetric epoxidation of styrene and its derivatives. The kcat. value of cis‐β‐methylstyrene epoxidation catalyzed by the quadruple mutant