Access to enantiopure aromatic epoxides and diols using epoxide hydrolases derived from total biofilter DNA
摘要:
Metagenomic DNA is a rich source of genes encoding novel epoxide hydrolases (EHs). We retrieved two genes encoding functional EHs from total DNA isolated from biofilter-derived biomass, using PCR with EH-specific degenerate primers followed by genome-walking PCR. The degenerate primers were based on two EH-specific consensus sequences: HGWP and GHDWG. The resulting recombinant EHs, Kau2 and Kau8, were expressed in Escherichia colt, and their enantioselectivity and regioselectivity were determined using 13 different epoxide substrates. The EH Kau2 had broad substrate specificity and preferentially hydrolyzed epoxides with S-configuration. It showed high enantioselectivity towards aromatic epoxides such as styrene oxide, p-nitrostyrene oxide, and trans-1-phenyl-1,2-epoxypropane. In addition, Kau2 showed enantioconvergent hydrolysis activity. The EH Kau8 also showed broad substrate specificity and preferentially hydrolyzed epoxides with R-configuration. High enantioselectivity was observed for p-nitrostyrene oxide, and the hydrolysis activity of Kau8 was less enantioconvergent than that of Kau2. To determine the usefulness of Kau2 for synthetic applications, preparative-scale biohydrolysis reactions were performed. Specifically, two kinetic resolutions were carried out with 80 g/L of racemic trans-1-phenyl-1,2-epoxypropane, affording both (1R,2R)-epoxide and the corresponding (1R,2S)-diol in high enantiomeric excess (>99%) and good yield (>45%). In addition, a process based on enantioconvergent hydrolysis by the EH Kau2 was established for racemic cis-1-phenyl-1,2-epoxypropane at a concentration of 13 g/L, resulting in the formation of the corresponding (1R,2R)-diol with a 97%yield and an enantiomeric excess exceeding 98%. (C) 2010 Elsevier B.V. All rights reserved.
Catalytic asymmetric Corey-Chaykovsky epoxidation of ketones with dimethyloxosulfoniummethylide 2 using an LLB 1a + Ar3P O complex proceeded smoothly at room temperature, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (91-97%) and yield (>88-99%) from a broad range of methyl ketones with 1-5 mol % catalyst loading. The use of achiral additive Ar3P O 5i was important
Microbiological Transformations 43. Epoxide Hydrolases as Tools for the Synthesis of Enantiopure α-Methylstyrene Oxides: A New and Efficient Synthesis of (<i>S</i>)-Ibuprofen
作者:M. Cleij、A. Archelas、R. Furstoss
DOI:10.1021/jo982101+
日期:1999.7.1
the enantioselectivity of these biohydrolyses strongly depends on the nature of the enzyme and of the substituent. Using some of these enzymes, this approach allows to prepare these epoxides in high optical purity. The potentiality to perform efficient preparative-scale resolution using such a biocatalyst was illustrated by the four-step synthesis of (S)-ibuprofen, a nonsteroidal antiinflammatory drug
Accessible sugars as asymmetric olefin epoxidation organocatalysts: glucosaminide ketones in the synthesis of terminal epoxides
作者:Omar Boutureira、Joanna F. McGouran、Robert L. Stafford、Daniel P. G. Emmerson、Benjamin G. Davis
DOI:10.1039/b911675c
日期:——
A systematically varied series of conformationally restricted ketones, readily prepared from N-acetyl-D-glucosamine, were tested against representative olefins as asymmetric epoxidation catalysts showing useful selectivities against terminal olefins and, in particular, typically difficult 2,2-disubstituted terminal olefins.
Synergistic Interplay of a Non-Heme Iron Catalyst and Amino Acid Coligands in H<sub>2</sub>O<sub>2</sub>Activation for Asymmetric Epoxidation of α-Alkyl-Substituted Styrenes
Highly enantioselectiveepoxidation of α‐substituted styrenes with aqueous H2O2 is described by using a chiral iron complex as the catalyst and N‐protected amino acids (AAs) as coligands. The amino acids synergistically cooperate with the iron center in promoting an efficient activation of H2O2 to catalyze epoxidation of this challenging class of substrates with good yields and stereoselectivities
通过使用手性铁络合物作为催化剂,使用N-保护的氨基酸(AAs)作为大分子配体,描述了使用水为H 2 O 2的α-取代的苯乙烯的高度对映选择性环氧化。氨基酸与铁中心协同作用,以促进H 2 O 2的有效活化,从而在较短的反应时间内以良好的收率和立体选择性(高达97%ee)催化这种具有挑战性的底物的环氧化 。
Highly enantioselective epoxidation of olefins by H<sub>2</sub>O<sub>2</sub> catalyzed by a non-heme Fe(<scp>ii</scp>) catalyst of a chiral tetradentate ligand
作者:Mainak Mitra、Olaf Cusso、Satish S. Bhat、Mingzhe Sun、Marco Cianfanelli、Miquel Costas、Ebbe Nordlander
DOI:10.1039/c8dt04449j
日期:——
ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results
手性四齿N4-供体配体1-甲基-2-((S)-2-[(S)-1-(1-甲基苯并咪唑-2-基甲基)吡咯烷-2-基]吡咯烷-1-基}基于手性二吡咯烷骨架的}甲基)苯并咪唑(S,S - PDBz L)已合成,并已制备并表征了其相应的Fe(II)配合物。配合物的X射线结构表明,Fe(II)离子处于扭曲的八面体配位环境中,两个顺式取向配位点被(不稳定的)三氟甲磺酸根阴离子占据。铁络合物催化烯烃与H 2 O 2的不对称环氧化反应的能力以2-环己烯-1-酮,2-环戊烯-1-酮,顺式-β-甲基苯乙烯,异佛尔酮,查耳酮和四氢萘酮为底物进行了研究。使用不同的羧酸作为添加剂来提高收率和对映选择性,发现2-乙基己酸的效果最佳。催化结果表明,Fe(II)配合物能够在环氧化反应中实现相对较高的对映选择性(> 80%)。