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磺酰氨基酸钛配合物对Diels-Alder反应的对映选择性催化作用 总被引:3,自引:0,他引:3
研究了对甲苯磺酰基-L-缬氨酸、对甲苯磺酰基-L-苯丙氨酸、对甲苯磺酰基-L-亮氨酸、对甲苯磺酰基-L-异亮氨酸、对甲苯磺酰基-L-脯氨酸、1-萘磺酰基-L-缬氨酸、1-萘磺酰基-L-苯丙氨酸、1-萘磺酰基-L-亮氨酸和1-萘磺酰基-L-异亮氨酸与钛的配合物对环戊二烯与丙烯酸甲酯的环加成反应的对映选择性催化作用。萘磺酰基氨基酸钛配合物的对映选择性比对甲苯磺酰基氨基酸钛配合物好,氨基酸与钛比为2:1时比1:1要好得多。1-萘磺酰基-L-异亮氨酸与钛的2:1配合物的对映选择性最好,e.e.值为56%。 相似文献
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合成了数个新手性双-(三氟甲磺酰)亚胺基二硫代缩酮基硅路易斯酸2~4, 并研究了它们对环戊二烯和丙烯酸衍生物11a~11c的Diels-Alder反应的催化活性. 结果表明催化剂活性高, 环加成反应的产率高达89%~96%, 并且获得较高的非对映选择性和中等对映选择性, 当催化剂为2b时, 反应的对映选择性达到最高, 为48% ee. 相似文献
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在过氧化氢酶和氧气存在下,固定化D-氨基酸氧化酶(D-AAO)对映选择性催化DL-氨基酸中的D-对映体氧化脱氨为相应酮酸,L-对映体保留.研究了D-AAO的底物特异性并对反应条件进行了优化.结果表明:D-AAO具有较宽的底物谱,能够催化疏水性α-氨基酸的D-对映体氧化脱氨.在最优反应条件下,D-AAO催化DL-2-氨基丁酸、DL-2-氨基戊酸去消旋化,L-2-氨基丁酸、L-2-氨基戊酸的收率分别为48%和47%,ee分别为99.5%和99.8%.进一步地利用Pd-C/HCOONH4催化氧化脱氨过程中产生的亚氨基酸原位还原,有效提高了L-2-氨基丁酸、L-2-氨基戊酸的收率并保持高的光学纯度. 相似文献
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手性三级炔丙醇是重要的药物中间体,而合成手性三级炔丙醇最简单的方法就是有机金属试剂对酮的对映选择性加成。然而,酮较低的亲电反应活性和羰基两侧立体化学位阻差异较低,使该反应较难于控制。为此我们合成了一系列β-磺酰胺基醇,并将其作为配体与Ti(OiPr)4一起催化炔基锌对简单非活化酮的不对称加成反应。经过筛选、测试,发现一β-磺酰胺基醇-钛复合物可在温和条件下,有效促进炔基锌对简单非活化酮的不对称加成,并且得到相应的手性三级炔丙醇,ee值达到了86%。我们提供了一个简单、可行且廉价的产生手性三级炔丙醇的方法。 相似文献
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不对称Diels-Alder (D-A)反应在有机合成中被广泛应用于手性二环类化合物的合成. 有机小分子催化的不对称D-A反应已有较多报道, 但对于烯酮与硝基烯烃的反应尚待进一步深入研究, 如反应是遵循Michael-Michael机理还是D-A机理?同时还没有能获得>86% ee值的光学选择性产物. 浙江工业大学徐振元等以设计的有机小分子1为催化剂、对三氟甲基苯甲酸为助催化剂, 在盐水溶液中实现了环己烯酮与硝基烯烃的不对称反应, 提出反应遵循如2所示原位烯胺活化的D-A机理, 同时以>25∶1 (exo∶endo)的立体选择性、55%~99%的收率和83%~96%的ee值得到相应的手性二环类化合物. 这一结果在所报道的文献中是最好的. 相似文献
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金鸡纳生物碱衍生手性双胺配体的合成及其在不对称氢转移反应中的催化作用 总被引:1,自引:0,他引:1
以价廉易得的天然金鸡纳生物碱奎宁和辛可宁为原料,在温和条件下容易地合成了6种手性双胺配体. 考察了它们与过渡金属Ir和Rh形成的配合物在苯乙酮不对称氢转移反应中的催化活性和不对称诱导作用. 结果表明, 9-氨基金鸡纳生物碱配体具有良好的不对称催化活性,而当配体中的氨基被取代后其对映选择性降低. 将9-氨基(9-脱氧)表辛可宁的Ir配合物用于其它芳香酮的不对称氢转移反应时,该配体也显示了很高的催化活性(80%~90%收率)和对映选择性(除对氯苯乙酮ee值为72%外,其余芳香酮ee值均为95%~97%). 相似文献
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《分子催化》2012,26(2)
在过氧化氢酶和氧气存在下,固定化D-氨基酸氧化酶(D-AAO)对映选择性催化DL-氨基酸中的D-对映体氧化脱氨为相应酮酸,L-对映体保留.研究了D-AAO的底物特异性并对反应条件进行了优化.结果表明:D-AAO具有较宽的底物谱,能够催化疏水性α-氨基酸的D-对映体氧化脱氨.在最优反应条件下,D-AAO催化DL-2-氨基丁酸、DL-2-氨基戊酸去消旋化,L-2-氨基丁酸、L-2-氨基戊酸的收率分别为48%和47%,ee分别为99.5%和99.8%.进一步地利用Pd-C/HCOONH4催化氧化脱氨过程中产生的亚氨基酸原位还原,有效提高了L-2-氨基丁酸、L-2-氨基戊酸的收率并保持高的光学纯度. 相似文献
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研究羧酸酯和磷酸酯的水解在环境和生物应用等方面具有越来越重要的意义。为实现对环境友好、高经济效益的生产过程,许多研究者致力于研发反应条件温和、催化效率高和高度专一性的催化剂。因而,仿酶研究倍受人们的关注,其中,水解金属酶是被研究得较为广泛的一类。我们曾报道过异羟肟酸过渡金属配合物仿生催化氧化性能和二氧亲合性能。本文我们将4种聚醚桥连二异羟肟酸过渡金属铜(Ⅱ)、锌(Ⅱ)、钴(Ⅱ)和锰(Ⅱ)配合物(见图1)作为仿水解酶模型,在底物浓度高于催化剂浓度10倍以上的条件下,研究了配合物在缓冲溶液中催化α-吡啶甲酸对硝基苯酯(PNPP)的水解反应的机理,并建立了相应的动力学数学模型;考查了配合物中心金属离子、溶液酸度和反应温度等对催化PNPP水解反应性能的影响。 相似文献
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Several chiral Schiff base ligands derived from α-amino acids were prepared, and zinc complexes with these chiral Schiff base ligands prepared were tested for the catalytic asymmetric hydrosilylation of ketones, and the results showed that excellent ee values were obtained, which are the prominent examples of catalytic asymmetric hydrosilylation of ketones catalyzed with zinc complexes in the presence of readily available and inexpensive α-amino acids based Schiff base ligands. 相似文献
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《Analytical letters》2012,45(13):2061-2077
A new analytical method is proposed for simultaneous determination of twenty organic acids in juices and beverages by eluent generator reagent free ion chromatography with electrospray ionization mass spectrometry (ESI–MS) in the negative selected ion monitoring mode (SIM). Twenty organic acids showed good linear relationship in the ranges of 0.5 ~ 20.0 mg/L. The correlation coefficients were more than 0.998, the detection limits were between 0.05 ~ 0.5 mg/L, and the average recoveries were between 88.0% ~ 106.0%. The relative standard deviations (RSDs) were less than 7.6%. The method has been applied to juice and beverage samples with satisfactory results. 相似文献
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The direct aldol reaction between a protected dihydroxyacetone derivative and 4-nitrobenzaldehyde catalyzed by chiral Zn2+ complexes of 1-(n-carboxylalkyl)-7-aminoacyl-1,4,7,10-tetraazacyclododecane is reported. New Zn2+ complexes containing l-histidine and carboxylalkyl chains that mimic a class II aldolase, carboxypeptidase A and a serine protease were designed and synthesized. Syn-aldol products were mainly formed by an aldol reaction of acetonide-protected dihydroxyacetone with benzaldehydes and other benzaldehydes in N-methylpyrrolidone (NMP)/alcohol (MeOH, EtOH or 2-PrOH) in good yields with a high degree of diastereo- and enantioselectivity (56%~quant., 57~>99% ee). Mechanistic aspect based on ESI-HRMS, elemental analysis and pH titrations of model ligands is also discussed. 相似文献
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Yuli He Chuang Liu Prof. Lei Yu Prof. Shaolin Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9271-9276
A redox-relay migratory hydroarylation of isomeric mixtures of olefins with arylboronic acids catalyzed by nickel complexes bearing diamine ligands is described. A range of structurally diverse 1,1-diarylalkanes, including those containing a 1,1-diarylated quaternary carbon, were obtained in excellent yields and with high regioselectivity. Preliminary experimental evidence supports the proposed non-dissociated chainwalking of aryl-nickel(II)-hydride species along the alkyl chain of alkenes before selective reductive elimination at a benzylic position. A catalyst loading as low as 0.5 mol % proved to be sufficient in large-scale synthesis while retaining high reactivity, highlighting the practical value of this transformation. 相似文献
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基于配合共保护策略合成γ-L-谷氨酰二肽的新方法 总被引:1,自引:0,他引:1
提出了一种采用谷氨酸席夫碱Ni(II)配合物共保护L-谷氨酸的α-氨基和α-羧基合成γ-L-谷氨酰二肽的新方法. 首先由手性助剂——2-[N-(N-苄基-脯氨酰)氨基]二苯甲酮(1)、六水合氯化镍和L-谷氨酸反应, 得到谷氨酸席夫碱Ni(II)配合物2, 产率为98.2%; 进而采用二异丙基碳二亚胺(DIC)/1-羟基-苯并三唑(HOBt)复合缩合剂法分别与L-氨基酸3a~3h反应, 得到相应的γ-L-谷氨酰二肽席夫碱Ni(II)配合物4a~4h, 产率为93.1%~99.0%; 最后稀酸水解配合物, 得到γ-L-谷氨酰二肽5a~5h, 产率为73.0%~86.4%, 高收率(92.2%~97.4%)回收手性助剂. 中间产物和终产物的结构经由旋光, 1H NMR, 13C NMR和HRMS表征. 相似文献
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Guram AS Wang X Bunel EE Faul MM Larsen RD Martinelli MJ 《The Journal of organic chemistry》2007,72(14):5104-5112
The new air-stable PdCl2[PR2(Ph-R')]2 complexes, readily prepared from commercial reagents, exhibit unique efficiency as catalysts for the Suzuki-Miyaura coupling reactions of a variety of heteroatom-substituted heteroaryl chlorides with a diverse range of aryl/heteroaryl boronic acids. The coupling reactions catalyzed by the new complexes exhibit high product yields (88-99%) and high catalyst turnover numbers (up to 10,000 TON). 相似文献
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Carmine Capacchione Daniela Saviello Antonietta Avagliano Antonio Proto 《Journal of polymer science. Part A, Polymer chemistry》2010,48(19):4200-4206
Copolymerization of ethylene with isoprene (IP) catalyzed by 1,4‐dithabutanediyl‐linked bis(phenolato) titanium complexes 1 and 2 and methylaluminoxane (MAO) produced exclusively ethylene‐IP copolymers with good activity. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with IP content ~60%. The copolymer microstructure was fully elucidated by 13C‐NMR spectroscopy of the copolymers with various IP content revealing a strong tendency to the alternating microstructure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4200–4206, 2010 相似文献
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The boron trifluoride induced Suzuki‐Miyaura cross‐coupling of aryltriazenes with arylboronic acids catalyzed by Pd(OAc)2 without added ligands has been achieved for the first time. The reactions performed at room temperature under an argon atmosphere give biaryls in good to excellent yields. It is noteworthy that the reactions were conducted under mild and ligand‐free conditions. 相似文献