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近平滑假丝酵母细胞催化乙酰基三甲基硅烷不对称还原反应 总被引:4,自引:0,他引:4
采用近平滑假丝酵母细胞用于催化乙酰基三甲基硅烷不对称还原反应, 可高选择性地生成 (R)-1-三甲基硅乙醇. 结果表明, 固定化于海藻酸钙的细胞催化该反应的产物收率比游离细胞的高. 不同辅底物对该反应的影响显著, 以葡萄糖为辅底物时, 反应的初速率较快, 产物收率较高. 该反应的最适条件为: 辅底物 (葡萄糖) 浓度 110 mmol/L, 振荡速度 180 r/min, 缓冲液 pH 值 6.0, 反应温度 30 oC, 底物浓度 20 mmol/L. 在此反应条件下反应的初速率、产物收率和产物的 ee 值分别为 11.4 μmol/h, 96.5% 和 99.9%. 相似文献
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木糖辅助底物对近平滑假丝酵母催化(R,S)-苯基乙二醇不对称氧化还原合成(S)-苯基乙二醇体系稳定性的促进作用 总被引:3,自引:0,他引:3
通过分析近平滑假丝酵母Candida parapsilosis催化外消旋苯基乙二醇(PED)不对称氧化还原合成(S)-苯基乙二醇的反应过程,结合微生物中糖类的代谢路径研究,建立了一种以木糖为辅助底物的NADPH辅酶再生的方法,提高了该催化系统的稳定性.结果表明,相同条件下反应体系中添加8 g/L的木糖可使(S)-PED产物的对映体过量值(ee)和产率分别提高14%和10%;菌体可重复使用3~4次,而产物ee值保持在98%.考察了木糖对表达羰基还原酶重组大肠杆菌体系催化效果的影响,发现木糖是通过强化(S)-羰基还原酶的催化作用提高了催化系统的稳定性,其原因是在磷酸戊糖途径中再生了氧化还原反应所需的NADPH辅酶. 相似文献
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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
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重组大肠杆菌细胞不对称还原4-氯乙酰乙酸乙酯合成(R)-(+)-4-氯-3-羟基丁酸乙酯 总被引:4,自引:0,他引:4
从赭色掷孢酵母(Sporobolomyces salmonicolor ZJU0105)中克隆出NADPH依赖型醛基还原酶基因,构建了重组大肠杆菌E.coli BL21(pET28-ALR0105), 该工程菌可以高效地表达醛基还原酶. 将重组细胞用于催化4-氯乙酰乙酸乙酯不对称还原,合成出具有光学活性的(R)-(+)-4-氯-3-羟基丁酸乙酯. 实验发现,在加入适量辅酶及辅酶再生酶的条件下,利用重组细胞催化还原反应可以获得比使用赭色掷孢酵母更高的转化率、产率和ee值,得到了几乎是光学纯的(R)-(+)-型产物,从而解决了酵母细胞催化此类反应ee值较低的问题. 考察了辅酶及共底物的添加、底物和产物的浓度、pH值、温度以及菌体密度等因素对还原反应的影响. 结果表明,不对称还原反应必须在辅酶NADPH和辅酶再生酶系及共底物葡萄糖的参与下进行; 底物和高浓度的产物对还原反应有一定的抑制作用; 当pH>6.0时,反应的转化率及产率都显著降低; 高密度重组细胞可以减小底物的抑制作用. 相似文献
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Kinetic Resolution of 2-Chloro-1-(3,4-dichlorophenyl)ethanol by Lipase-Catalyzed Transesterification
Kinetic resolution of racemic 2-chloro-1-(3,4-dichlorophenyl)ethanol was performed by free Alcaligene sp. lipase-catalyzed irreversible transesterification affording the (R)-isomer with ≥95% ee and the (S)-isomer with ≥90% ee. The activity of lipase Alcaligene sp. strongly depends on the basicity of the reaction system, and an organic base such as triethylamine can enhance the activity of the lipase and enantioselectivity markedly. 相似文献
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用Pseudomonas stutzeri脂肪酶催化转酯化反应动力学拆分外消旋体法制备高对映体纯的手性2-氯-1-(2,4-二氟苯基)乙醇, 得到95.8% ee值的(R)-异构体和94.5% ee值的(S)-异构体, 以此手性醇为关键中间体合成了4种具有抗真菌活性的光学活性化合物α-氯代苄氧基-β-(1-咪唑基)-2,4-二氟乙苯硝酸盐. 纸片扩散法测试体外抗真菌活性结果表明, 对各种念珠菌(Candida species) (R)-5a和(R)-5b具有与氟康唑相当的抗菌活性, 特别是对氟康唑耐药的烟曲霉菌(Aspergillus fumigatus), 5a, 5b及其两种光学活性异构体均有优异的抗菌活性, 而且(R)-异构体的活性明显高于(S)-异构体和外消旋体. 相似文献
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The title compound (R)-N'-[2-(4-methoxy-6-chloro)-pyrimidyl]-N-[3-methyl-2-(4-chlorophenyl)butyryl]-urea has been synthesized, and its crystal structure and biological behaviors were studied. Crystallographic data: C17H18Cl2N4O3, Mr = 397.25, monoclinic, space group P21/c, a = 12.331 (2), b = 14.025(3), c = 23.085(5) (A), β = 99.607(4)°, Z = 8, V = 3936.2(13) (A)3, Dc = 1.341 g/cm3, F(000) = 1648, R = 0.0718, wR = 0.1585 and μ(MoKα) = 0.353 mm-1. The preliminary biological tests showed that the title compound has definite insecticidal and fungicidal activities. 相似文献
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(S)-1-(2,6-二氯-3-氟苯基)乙醇(2)是合成抗癌药物克唑替尼的关键手性前体。本文以1-(2,6-二氯-3-氟苯基)乙酮为起始原料,利用二异松莰基氯化硼[(-)-Ipc2BCl]不对称还原制得光学纯的2;并将中间体2经Mitsunobu反应、还原、溴代、 Suzuki偶联及脱除Boc保护合成克唑替尼,其结构1H NMR,13C NMR和HR-MS(ESI)确证。对关键中间体2的合成条件进行了优化,并其对反应机理进行了推测。 相似文献
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YING Hua-Zhou SUN Mao-Tang LIU Tao HU Yong-Zhou① 《结构化学》2008,27(10):1171-1174
The title compound 2-(2-chloro-4-nitrophenyl)-4-(4-chlorophenyl)-3a,4- diethoxy- 2,3,3a, 4-tetrahydrochromeno[3,4-d][1,2,3]diazaphosphole 2 (C29H30Cl2N3O7P, Mr = 633.44) was synthesized and its structure was characterized by IR, MS, ^1H NMR, ^13C NMR, ^31p NMR, elemental analysis and single-crystal X-ray diffraction. It crystallizes in triclinic, space group P1^-, a = 9.1549(3), b = 10.7168(4), c = 17.6272(6)A, α = 102.9363(12), β = 90.2713(9), γ = 117.4265(10)°, V= 1484.41(9)A^3, Z= 2,μ(MoKa) = 0.323, F(000) = 658, Z= 2, De= 1.417 g/cm^3, the final R = 0.0687 and wR = 0.2066 for 4943 observed reflections (I 〉 2σ(I)). X-ray analysis reveals that the diazaphospholine ring is almost planar and the two ethoxy groups bonded on the 3a- and 4-positions are in trans configurations. Its antiproliferative activity was also tested in vitro against four human tumor cell lines. 相似文献
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(R)-2-Chloro-l-(m-chlorophenyl)ethanol,a precursor of(R)-3-chlorostyrene oxide which is the key chiral intermediate for the preparation of severalβ3-adrenergic receptor agonists was prepared in 40%yield and 99%ee by the Lipozyme TL IM-catalyzed second resolution of the corresponding racemate in the presence of vinyl acetate. 相似文献
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The reduction of prochiral ketones using chiral reducing reagents, prepared from lithium aluminum hydride and (-)-(1R, 2S, 3S, 5R)-10-anilinopinanediol (5) and (-)-(1R, 2S, 3S, 5R)-10-N-methylanilinopinanediol (6), affords chiral secondary alcohols in useful chemical yields (70 ~ 93%) but in low optical purity (8 ~ 33% ee). Modifiers 5 and 6 are synthesized from (lR)-(-)-β-pinene in three steps. 相似文献
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CHEN Long XUE Si-Jia FANG Zhi-Kun YIN An-Qin XU Yang 《结构化学》2009,28(8):990-994
A novel compound N-(pyridine-2-methyl)-2-(4-chlorophenyl)-3-methylbutanamide, a racemic compound, has been synthesized with 2-(4-chlorophenyl)-3-methylbutyric acid and pyridin- 2-methylanamine as the raw materials, and its crystal structure (C17H19C1N2O, Mr = 302.79) was determined by single-crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/n with a = 9.624(9), b = 23.14(2), c = 15.626(15)A, β = 106.199(14)°, V = 3342(5) A^3, Z = 8, Dc = 1.204 g/cm^3,μ = 0.23 mm^-1, F(000) = 1280, S = 1.032, R = 0.0681 and wR = 0.1508 for 6513 unique reflections (Rint = 0.0421) with 3375 observed ones. In the crystal structure, there are some intermolecular hydrogen bonds which stabilize the crystal structure. The preliminary bioassay shows that the title compound exhibits good antifungal activity against Botrytis cinerea, Gibberella zeae, Dothiorella gregaria and Colletotrichum gossypii. 相似文献
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3-Chloro-2-polyfluoroalkyl- and 3-chloro-6-nitro-2-polyfluoroalkylchromones were synthesized. These compounds react with N2H4·2HCl on boiling in ethanol to form 4-chloro-3(5)-(2-hydroxyaryl)-5(3)-polyfluoroalkylpyrazoles. 相似文献
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有机相酶催化拆分制备(S)-2-氯-1-(2-噻吩)-乙醇 总被引:1,自引:0,他引:1
首次在有机相中对酶催化条件下的2-氯-1-(2-噻吩)-乙醇的反应进行了研究. 通过对不同来源酶的筛选, 找到了Novozym 435和Alcaligenes sp两种选择性较好的酶, 它们均对该反应具有较高的选择性和较快的反应速度, 在此基础上进一步通过对溶剂、温度、摇床转速以及酶用量的筛选, 确定了能够有效拆分2-氯-1-(2-噻吩)-乙醇的较佳反应条件. 当温度35 ℃, 酶量10 mg/mL, 反应72.5 h, 产物的ee值为98.5%时收率为48.6%. 相似文献