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Theresa Schmidt Niels Heise Kurt Merzweiler Hans-Peter Deigner Ahmed Al-Harrasi Ren Csuk 《Molecules (Basel, Switzerland)》2021,26(12)
Furan-2-carboxylic acid was used as a starting material for the synthesis of dehydro-homopilopic acid. Esterification, hydrogenation and enzymatic hydrolysis followed by the reduction of Weinreb amides and a single-step attachment of a 1-methyl-imidazole residue allowed for the concise synthesis of both enantiomers of pilocarpine. 相似文献
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Starting from propargyl alcohol ( 12 ), and on the basis of Zhou's modified Sharpless asymmetric epoxidation, the sex pheromone of the Gypsy moth, disparlure (+)‐ 8 and its enantiomer (?)‐ 8 have been synthesized, each in six steps, with overall yields of 29% for (+)‐ 8 and 27% for (?)‐ 8 (ee>98%). The use of the sequential coupling tactic renders the method flexible, which is applicable to the synthesis of other cis‐epoxy pheromones. 相似文献
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A new enantioselective synthesis of furan‐2‐yl amines and amino acids is described, in which the key step is the oxazaborolidine‐catalyzed enantioselective reduction of O‐benzyl (E)‐ and (Z)‐furan‐2‐yl ketone oximes to the corresponding chiral amines. The chirality of the furan‐2‐yl amines is fully controlled by the appropriate choice of the geometrical isomer of the O‐benzyl oxime. Oxidation of the furan ring furnished amino acids in high yields. 相似文献
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An efficient enantiospecific synthesis of the (R)‐ and (S)‐enantiomers of flavanone and 2‐methylchromanone is described. The key steps are a C,C‐bond formation by ring opening of a chiral epoxide with a dithiane anion, followed by a Mitsunobu cyclization. The products obtained have high enantiomeric purity. 相似文献
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手性配体立体选择性萃取分离扁桃酸对映体 总被引:6,自引:0,他引:6
Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the partition of Cu2+ in the two-phase system containing N-n-dedecane-L-hydroxyproline, was investigated. The formation constant of binary cpmplex(Li2Cu) was obtained by regression. The influence of pH, concentrations of Cu2+ and chiral ligand, and solvents on partition coefficients(K) and separation factor(α), was discussed. The experimental results show that Li forms more stable ternary complex with D-mandelic acid than with L- mandelic acid. There is a large influence of pH on K and α. At low pH values (<3.5), formation of binary complexes is thermodynamically unfavourable. K and α are best when pH values are above 3.5 and the molar ratio of chiral ligand to Cu2+ is 2∶1. At the same time, solvents influence K and α very much. 相似文献
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基于手性配体交换反应立体选择性萃取分离氧氟沙星对映体 总被引:4,自引:0,他引:4
基于配体交换反应,研究了氧氟沙星对映体在含有Cu2+和N-n-十二烷基-L-脯氨酸手性配体(L)两相体系中的分配平衡.在不同pH条件下,考察了Cu2+在含有N-n-十二烷基-L-脯氨酸两相中的分布;研究了pH,Cu2+浓度,手性配体浓度等因素对氧氟沙星对映体在两相中的分配系数(K)和分离因子(α)的影响.实验结果表明,N-n-十二烷基-L-脯氨酸对R-氧氟沙星对映体萃取能力大于对S-对映体的萃取能力;pH对K和α的影响很大,在pH值小于3.5时,L2Cu二元配合物的生成在热力学上看是不适宜的,萃取时pH宜大于3.5;手性配体和Cu2+摩尔比为2:1,K和α最佳;使用2×1中空纤维膜对氧氟沙星对映体进行萃取分离,出口水相氧氟沙星对映体浓度比值(S/R)约为1.72. 相似文献
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D-Glucose was transformed stereoselectively into (7R,8S)8-benzyloxy-7-hydroxy-2-methyl-9-octadecene from which both enantiomers of disparlure, (7R,8S)-(+)-and (7S,8R)-(-)-7,8-epoxy-2-methyloctadecane, sex pheromone of the gypsy moth, were obtained in four and three steps, respectively. 相似文献
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Followingthedevelopmentoffullerenefunctionalization',therehasbeenanincreasinginterestinthesynthesisofchiralfullerenederivativesfortheirpotentialapplicationintheareasofpharmaceuticalsandoptics'~'.Introductionofchiralityfromthechiralsubstituenttothefullerenecore3hasbeenestablishedtobeoneofthemostversatilemethodsforthechiralfullerenederivatives.Inthisway,chiralweresynthesizedbyVasellaetap.ThesynthesisandCDspectraoffullerene-peptideswerereportedbyPratoandco-workers',aswellasDiederich'sgroup'.Rec… 相似文献
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A cyclic analogue 4 of galardin, a known MMP inhibitor, is designed to improve its selectivity. The synthesis of 4 starts from dimethyl (S)‐malate using diaselective alkylation and subsequent cyclization and amide formation as key steps. The compound 4 showed MMP inhibitory activity on all MMPs tested with IC30, ranging from 20.1 μM to 104 μM. 相似文献
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Penicillamine, cysteine, and N-isobutyryl-cysteine enantiomers self-assembled gold electrodes were used for the enantioselective recognition of proline in the presence of copper(II). High stereoselectivity for proline was obtained for the D-form of the sulfhydryl compounds, particularly on the D-penicillamine-modified gold electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were used to confirm the chiral discrimination of proline enantiomers on the D-penicillamine modified gold electrode in the presence of copper(II). The largest electrochemical response was obtained for D-proline for the recognition of its enantiomers, whereas small responses were obtained for the L- and D-forms of phenylalanine, tyrosine, serine, and glutamic acid. The influences of incubation time and pH for chiral ligand exchange were evaluated. This study complements and enhances applications for the recognition of amino acid enantiomers based on ligand exchange by electrochemical analysis. 相似文献
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Several methodologies to produce α-terpinyl chloride from “hydrochlorination” of limonene were studied and the best results were obtained by reaction with 0.5 mol equiv. SOCl2 in SiO2 / CH2Cl2. Using this methodology (R)- and (S)-α-terpinyl chloride can easily be prepared in good yields from (R)- and (S)-limonene, respectively. 相似文献
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E.Peter Kündig MundruppadyS. Laxmisha Rita Cannas Sylvie Tchertchian Liu Ronggang 《Helvetica chimica acta》2005,88(5):1063-1080
An efficient dearomatization process of [Cr(arene)(CO)3] complexes initiated by a nucleophilic acetaldehyde equivalent is detailed. It generates in a one‐pot reaction three C? C bonds and two stereogenic centers. This process allowed a rapid assembly of a cis‐decalin ring system incorporating a homoannular diene unit in just two steps starting from aromatic precursors (Scheme 2). The method was applied to the total synthesis of the eudesmane‐type marine furanosesquiterpene (±)‐15‐acetoxytubipofuran ( 2 ). Two routes were successfully used to synthesize the γ‐lactone precursor of the furan ring. The key step in the first approach was a Pd‐catalyzed allylic substitution (Scheme 3), while in the second approach, an Eschenmoser–Claisen rearrangement was highly successful (Scheme 4). The Pd‐catalyzed allylic substitution could be directed to give either the (normal) product with overall retention as major diastereoisomer or the unusual product with inversion of configuration (see Table). For the synthesis of the (?)‐enantiomer (R,R)‐ 2 of 15‐acetoxytubipofuran, an enantioselective dearomatization in the presence of a chiral diether ligand was implemented (Scheme 7), while the (+)‐enantiomer (S,S)‐ 2 was obtained via a diastereoselective dearomatization of an arene‐bound chiral imine auxiliary (Scheme 8). Chiroptical data suggest that a revision of the previously assigned absolute configuration of the natural product is required. 相似文献
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在锂存在的条件下在正戊醇中回流环化四聚相应的光学活性的前驱体联二萘[2,1-e:1',2'-g][1,4]二羟基-5,6-邻苯二氰, 然后用醋酸酸化处理, 合成了一对对映的四个联二萘酚基团取代的手性自由酞菁四(联二萘[1,2-e:1',2'-g]-1,4-二羟基)[2,3-b;2',3'-k;2',3'-t;2'',3''-c']酞菁(1), 并利用一系列的光谱学方法以及元素分析表征了这种新型的手性酞菁化合物. 单晶X衍射分析确定了两种对映体的绝对构型, 从而阐明了自由酞菁(1)的手性分配. 相似文献