共查询到20条相似文献,搜索用时 15 毫秒
1.
Xuri Wu Yuchen Wang Jianming Ju Chen Chen Nan Liu Yijun Chen 《Tetrahedron: Asymmetry》2009,20(21):2504-2509
Recombinant diketoreductase showed excellent stereoselectivity in the double reduction of β,δ-diketo esters. To investigate the substrate specificity and to broaden the applications of this new biocatalyst, a number of ketone substrates were used to evaluate the substrate spectrum and enantioselectivity of this enzyme in the present study. Among the ketone substrates tested, only this enzyme displayed high efficiency and excellent enantioselectivity in the reduction of ethyl 2-oxo-4-phenylbutyrate to ethyl (S)-2-hydroxy-4-phenylbutyrate. After optimizing the reaction conditions, the bio-reduction of ethyl 2-oxo-4-phenylbutyrate at a substrate concentration of 0.8 M (164.8 g/L) was achieved by the recombinant diketoreductase in an aqueous-toluene biphasic system coupled with formate dehydrogenase for the regeneration of cofactor, resulting in an overall hydroxyl product yield of 88.7% (99.5% ee). This new enzymatic transformation may offer a practical method for the preparation of this important chiral building block. 相似文献
2.
研究了异丁醛与乙醛酸乙酯不对称羟醛缩合反应合成(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯,考察了催化剂种类及用量、反应时间、反应溶剂对羟醛缩合反应的影响。确定较佳反应条件为:L-组氨酸作催化剂,用量为乙醛酸乙酯物质的量的30%,乙二醇为溶剂,反应时间24h。(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯的收率达75%,ee值为73%。产物结构经1H NMR,GC-MS进行了表征。 相似文献
3.
《Tetrahedron: Asymmetry》2001,12(11):1583-1587
With the readily available l-malic acid as starting material, both enantiomers of ethyl 2-hydroxyl-4-phenylbutanoates and d-homophenylalanine ethyl ester hydrochloride were prepared conveniently in excellent optical purity and 64, 53 and 49% overall yield, respectively. 相似文献
4.
5.
《Tetrahedron: Asymmetry》1999,10(20):3931-3937
3,4-Dichlorophenacylchloride was reduced with whole cell biocatalysts to give the (R)- or (S)-chlorohydrine in high yields and good to high enantiomeric excess. Yields and enantiomeric purity of the (S)-enantiomer were increased to 95 and >98%, respectively, using growing cells from Geotrichum candidum (CBS 233.76) in the presence of hydrophobic adsorbing resins at 4 g/l. The latter compound was transformed into (R)-3,4-dichlorophenylbutanolide, intermediate in the synthesis of (+)-cis-1S,4S-sertraline. 相似文献
6.
7.
8.
9.
《Tetrahedron: Asymmetry》1998,9(21):3855-3861
A chemo-enzymatic synthesis of the four stereoisomers of 4-hydroxy-4-methylglutamic acid is described. As with other glutamate analogues these compounds can serve as probes for the investigation of glutamate receptors. 相似文献
10.
11.
《Tetrahedron letters》2019,60(41):151134
A first chiral strategy for synthesis of (R)-5-hydroxy-3-(4-methoxyphenethyl) cyclohex-2-enone reported. Key transformation includes Barbier allylation, ionic hydrogenation, Jeffery reaction, Katsuki Sharpless asymmetric epoxidation, reductive opening of epoxide and ring closing metathesis. 相似文献
12.
13.
不对称还原制备光学纯(R)-2-羟基-4-苯基丁酸乙酯的双酶共表达重组菌的构建 总被引:1,自引:0,他引:1
克隆了来自于枯草芽孢杆菌的羰基还原酶基因IolS和葡萄糖脱氢酶基因GDH,采用Ni-NTA镍亲和层析柱对重组蛋白IolS进行纯化,并对纯酶进行了酶学性质研究.结果表明,该羰基还原酶的最适温度和pH值分别为30oC和6.0;在40oC以下具有较好的热稳定性;在pH5.57.0的偏酸性范围内能保持75%以上的酶活.采用三种策略构建了IolS和GDH的共表达重组质粒,结果发现,采用双启动子的重组质粒能够实现羰基还原酶IolS的高效表达,粗酶液中的IolS和GDH的比酶活均达到1.5U/mg.运用该重组菌对10g/L的OPBE进行不对称还原,反应15h后,底物转化率大于99%,产物(R)-2-羟基-4-苯基丁酸乙酯的ee值达到99.5%. 相似文献
14.
T. S. Zhivotova A. M. Gazaliev M. K. Ibraev D. M. Turdybekov K. M. Turdybekov S. D. Fazylov 《Russian Journal of General Chemistry》2006,76(1):122-125
2-Hydroxy-2-(p-nitrophenyl)ethyl morpholine-4-carbodithioate was synthesized by reaction of p-nitrophenyloxirane with carbon disulfide and morpholine, and its molecular structure was studied by the X-ray diffraction method. 相似文献
15.
16.
17.
I. V. Mineeva 《Russian Journal of Organic Chemistry》2013,49(5):712-716
A simple and efficient asymmetric synthesis was performed of (+)-(S)-7,8-dihydrokanian and (4R,6R)-4-hydroxy-6-(2-phenylethyl)tetrahydro-2H-pyran-2-one involving Keck allylation in the key stage of building up the carbon scaffold of the target molecules. 相似文献
18.
Ta-jyh Lee 《Tetrahedron letters》1979,20(25):2297-2300
The title compound , a key intermediate for PGE2 elaboration, is readily available in nine steps from furfuryl alcohol. The crucial steps include the exclusive formation of from and the subsequent intramolecular Aldol condensation to . 相似文献
19.
Manuel Velasco Ulises Hernández Joel L. Terán Dino Gnecco María L. Orea David M. Aparicio Víctor Gómez-Calvario Sylvain Bernès Jorge R. Juárez 《Tetrahedron letters》2019,60(12):820-824
The stereoconvergent synthesis of N-Boc-(2R,3S)-3-hydroxy-2-phenylpiperidine from (R)-1-(2-((tert-butyldimethylsilyl)oxy)-1-phenylethyl)piperidin-2-one is described. The key steps involved are α-hydroxylation of quiral lactam with O2, stereoconvergent reduction of (R)- or (S)-3-(benzyloxy)-piperidin-2-one with Red-Al® which afforded in both cases the trans-bicyclic oxazolidine in high stereoselectivity after chromatographic purification and a stereospecific Grignard addition to chiral bicyclic oxazolidine. 相似文献
20.
Yanagi T Kikuchi K Takeuchi H Ishikawa T Nishimura T Yamamoto I 《Chemical & pharmaceutical bulletin》2001,49(8):1018-1023
The synthetic route for a uterine relaxant, bis(2-[[(2S)-2-([(2R)-2-hydroxy-2-[4-hydroxy-3-(2-hydroxyethyl)-phenyl]ethyl]amino)-1,2,3,4-tetrahydronaphthalen-7-yl]oxy]-N,N-dimethylacetamide) sulfate (KUR-1246), was established by the coupling of optically active components, the bromohydrin 14 and the amine 24. We now describe the practical synthesis of these two optically active components. Bromohydrin 14 was obtained by the asymmetric borane reduction of the prochiral phenacyl bromide 13 using a catalyst prepared from aluminum triethoxide and a chiral amino alcohol. The other optically active component 24 was prepared from (S)-AMT. 相似文献