50618-02-5Relevant academic research and scientific papers
Cobalt-Catalyzed Z to e Isomerization of Alkenes: An Approach to (E)-β-Substituted Styrenes
Liu, Hongmei,Xu, Man,Cai, Cheng,Chen, Jianhui,Gu, Yugui,Xia, Yuanzhi
supporting information, p. 1193 - 1198 (2020/02/04)
An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.
A General Regioselective Synthesis of Alcohols by Cobalt-Catalyzed Hydrogenation of Epoxides
Beller, Matthias,Junge, Kathrin,Leischner, Thomas,Li, Wu,Liu, Weiping
supporting information, p. 11321 - 11324 (2020/05/16)
A straightforward methodology for the synthesis of anti-Markovnikov-type alcohols is presented. By using a specific cobalt triphos complex in the presence of Zn(OTf)2 as an additive, the hydrogenation of epoxides proceeds with high yields and selectivities. The described protocol shows a broad substrate scope, including multi-substituted internal and terminal epoxides, as well as a good functional-group tolerance. Various natural-product derivatives, including steroids, terpenoids, and sesquiterpenoids, gave access to the corresponding alcohols in moderate-to-excellent yields.
Enhanced Turnover for the P450 119 Peroxygenase-Catalyzed Asymmetric Epoxidation of Styrenes by Random Mutagenesis
Wang, Li,Wei, Siping,Pan, Xianchao,Liu, Pingxian,Du, Xi,Zhang, Chun,Pu, Lin,Wang, Qin
, p. 2741 - 2749 (2018/02/28)
A randomized library is constructed based on pET30a-CYP119-T214V plasmid. This library of random mutants of CYP119-T214V was screened by means of the reduced CO difference spectra and epoxidation of styrene. By using directed evolution, a new CYP119 quadr
Umpolung Synthesis of 1,3-Amino Alcohols: Stereoselective Addition of 2-Azaallyl Anions to Epoxides
Daniel, Paige E.,Weber, Alexandria E.,Malcolmson, Steven J.
supporting information, p. 3490 - 3493 (2017/07/15)
We report the direct preparation of 1,3-amino alcohols that contain up to three contiguous stereogenic centers by the umpolung coupling of imines and epoxides. Nucleophilic 2-azaallyl anions, generated from imines, are stereoselectively added to epoxides to furnish 1,3-amino alcohols after hydrolysis of the product imine. Transformations afford amino alcohols with >98% site selectivity with respect to both reaction partners and in up to >98% yield and >20:1 dr.
Engineering P450 Peroxygenase to Catalyze Highly Enantioselective Epoxidation of cis-β-Methylstyrenes
Zhang, Chun,Liu, Ping-Xian,Huang, Lu-Yi,Wei, Si-Ping,Wang, Li,Yang, Sheng-Yong,Yu, Xiao-Qi,Pu, Lin,Wang, Qin
, p. 10969 - 10975 (2016/07/27)
P450 119 peroxygenase and its site-directed mutants are discovered to catalyze the enantioselective epoxidation of methyl-substituted styrenes. Two new site-directed P450 119 mutants, namely T213Y and T213M, which were designed to improve the enantioselectivity and activity for the epoxidation of styrene and its methyl substituted derivatives, were studied. The T213M mutant is found to be the first engineered P450 peroxygenase that shows highly enantioselective epoxidation of cis-β-methylstyrenes, with up to 91 % ee. Molecular modeling studies provide insights into the different catalytic activity of the T213M mutant and the T213Y mutant in the epoxidation of cis-β-methylstyrene. The results of the calculations also contribute to a better understanding of the substrate specificity and configuration control for the regio- and stereoselective peroxygenation catalyzed by the T213M mutant.
Visible light-mediated oxidative quenching reaction to electron-rich epoxides: Highly regioselective synthesis of α-bromo (di)ketones and mechanism study
Guo, Lin,Yang, Chao,Zheng, Lewei,Xia, Wujiong
supporting information, p. 5787 - 5792 (2013/09/12)
A novel and simple procedure was developed for the regioselective synthesis of α-bromo (di)ketones from electron-rich epoxides via visible light photoredox catalysis. Through optimization of solvent and light source, the reaction can be rapidly achieved under mild conditions. Moreover, the possible reaction mechanism was proposed and further supported by control experiments.
Exploring substrate scope of Shi-type epoxidations
Nieto, Natalia,Munslow, Ian J.,Fernández-Pérez, Héctor,Vidal-Ferran, Anton
experimental part, p. 2856 - 2858 (2009/05/07)
Enantioselective epoxidations of alkenes (12 examples) were achieved using a Shi-type carbohydrate-derived hydrate and Oxone. The chiral platform provided by the catalyst tolerates a wide range of substituents providing high yields and enantioselectivities (80-95.5% ee). However, styrene derivatives were only converted with poor selectivities (11-26% ee). Georg Thieme Verlag Stuttgart.
Synthetic, spectral and catalytic activity studies of ruthenium bipyridine and terpyridine complexes: Implications in the mechanism of the ruthenium(pyridine-2,6-bisoxazoline)(pyridine-2,6-dicarboxylate)-catalyzed asymmetric epoxidation of olefins utilizing H2O2
Tse, Man Kin,Jiao, Haijun,Anilkumar, Gopinathan,Bitterlich, Bianca,Gelalcha, Feyissa Gadissa,Beller, Matthias
, p. 4419 - 4433 (2007/10/03)
Various Ru(L1)(L2) (1) complexes (L1 = 2,2′-bipyridines, 2,2′:6′,2″-terpyridines, 6-(4S)-4-phenyl-4,5-dihydro-oxazol-2-yl-2,2′-bipyridinyl or 2,2′-bipyridinyl-6-carboxylate; L2 = pyridine-2,6-dicarboxylate, pyridine-2-carboxylate or 2,2′-bipyridinyl-6-carboxylate) have been synthesized (or in situ generated) and tested on epoxidation of olefins utilizing 30% aqueous H2O2. The complexes containing pyridine-2,6-dicarboxylate show extraordinarily high catalytic activity. Based on the stereoselective performance of chiral ruthenium complexes containing non-racemic 2,2′-bipyridines including 6-[(4S)-4-phenyl-4,5-dihydro-oxazol-2-yl]-[2,2′]bipyridinyl new insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed enantioselective epoxidation are proposed. In addition, a simplified protocol for epoxidation of olefins using urea hydrogen peroxide complex as oxidizing agent has been developed.
Convenient method for epoxidation of alkenes using aqueous hydrogen peroxide
Man, Kin Tse,Klawonn, Markus,Bhor, Santosh,Doebler, Christian,Anilkumar, Gopinathan,Hugl, Herbert,Maegerlein, Wolfgang,Beller, Matthias
, p. 987 - 990 (2007/10/03)
(Chemical Equation Presented) The complex [Ru(tpy)(pydic)] (1a) is an active catalyst for epoxidation of alkenes by aqueous 30% hydrogen peroxide in tertiary alcohols. The protocol is simple to operate and gives the corresponding epoxides in good to excellent yields. Chiral enantiopure [Ru(tpy*)(pydic) ] complexes have been synthesized and successfully applied in this procedure.
Acid-Catalyzed Hydrolysis of cis- and trans-Anethole Oxides: Discrete Carbocation Intermediates and Syn/Anti Hydration Ratios
Mohan, Ram S.,Whalen, Dale L.
, p. 2663 - 2669 (2007/10/02)
Rate and product studies of the hydronium ion-catalyzed hydrolysis reactions of trans-anethole oxide (12b) and its geometric isomer, cis-anethole oxide (13b), were carried out.Acid-catalyzed hydrolysis of trans-anethole oxide is 50 times faster than that of its cis isomer and this difference in reactivity is attributed to steric interactions between the cis-β-CH3 and the aryl group in the transition state for hydrolysis of cis-anetole oxide that are not present in the transition state for the acid-catalyzed hydrolysis of trans-anethole oxide.Carbocation intermediates in the hydrolysis of both 12b and 13b are trapped, subsequent to their rate-limiting formation, by azide ion.Identical diol product mixtures from the acid-catalyzed hydrolysis of both 12b and 13b, and identical azide product mixtures from their reactions in solutions at low pH containing sodium azide, suggest that both 12b and 13b react to form a common discrete carbocation intermediate and that products are derived from reaction of this intermediate with nucleophiles.Molecular modeling calculations suggest that there are three minimum energy conformations of this carbocation intermediate.Results are interpreted in terms of a mechanism in which rotation about the Cα-Cβ bond of the intermediate is rapid relative to the rate at which it reacts with solvent or other nucleophiles.Mechanisms involving concerted addition of solvent are ruled out.
