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1.
Srinivas Chandrasekaran Masaki Tambo Yuta Yamazaki Tatsuro Muramatsu Yusuke Kanda Takuji Hirose Koichi Kodama 《Molecules (Basel, Switzerland)》2023,28(1)
Enantioseparation of 3-hydroxycarboxylic acids via diastereomeric salt formation was demonstrated using 2-amino-1,2-diphenylethanol (ADPE) and cinchonidine as the resolving agents. Racemic 3-hydroxy-4-phenylbutanoic acid (rac-1), 3-hydroxy-4-(4-chlorophenyl)butanoic acid (rac-2), and 3-hydroxy-5-phenylpentanoic acid (rac-3) were efficiently resolved using these resolving agents. Moreover, the successive crystallization of the less-soluble diastereomeric salt of 1 and cinchonidine using EtOH yielded pure (R)-1 · cinchonidine salt in a high yield. The crystal structures of less-soluble diastereomeric salts were elucidated and it was revealed that hydrogen bonding and CH/π interactions play an important role in reinforcing the structure of the less-soluble diastereomeric salts. 相似文献
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Dorottya Fruzsina Bnhegyi Elemr Fogassy Jnos Madarsz Emese Plovics 《Molecules (Basel, Switzerland)》2022,27(10)
The optically active dibenzoyltartaric acid, tartaric acid, and its sodium salts were successfully applied to the optical resolution of (1R,2S)(1S,2R)-2-(methylamino)-1-phenylpropan-1-ol (EPH) and (1R,2R)(1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diol (AD) as resolving agents. It was observed that both compounds’ resolution using a mixture of salts of quasi-racemic resolving agents showed a change in chiral recognition under the same conditions compared to the result of the use of the single enantiomeric resolving agent. The changes are followed by detailed analytical (XRD, FTIR, and DSC) studies. Meanwhile, the DASH indexing software package was also tested on powder XRD patterns of pure initial materials and intermediate salt samples of high diastereomeric excess. 相似文献
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Gottfried Blaschke 《Angewandte Chemie (International ed. in English)》1980,19(1):13-24
A number of racemates can be resolved into optically pure enantiomers by chromatography on optically active adsorbents. Synthetic polymers with optically active amide, amino acid, and crown ether groups, natural products such as starch and cellulose, and also microcrystalline triacetylcellulose are suitable for this purpose. Racemates can also be resolved by gas chromatography on optically active stationary phases. 相似文献
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本文总结了手征性氟代醇、酸、胺、联苯类,由于分子过分拥挤而造成的不对称化合物及手征性全氟化合物的拆分。阐述了这项工作在生物化学、有机合成、有机分析以及有机反应机理的研究等方面的特殊意义。 相似文献
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通过形成二酪氨酸酯酒石酸盐法制备D-酪氨酸的新方法 总被引:1,自引:0,他引:1
研究了在乙醇溶液中光学活性L-酒石酸拆分DL-酪氨酸乙酯时的特性, 发现溶液中同时存在着酒石酸、酪氨酸乙酯酒石酸氢盐和二酪氨酸乙酯酒石酸盐, 三者之间的平衡关系影响拆分结果, 所得酪氨酸的构型与L-酒石酸和DL-酪氨酸乙酯的投料摩尔比有关. 前者的摩尔数大于后者时为富D-酪氨酸乙酯, 小于后者时为富L-酪氨酸乙酯, 两者相当时则得到DL-酪氨酸乙酯. 进一步的研究探讨了D-酒石酸、L-酒石酸与L-酪氨酸乙酯在不同摩尔比下的成盐特性, 从而解释了酒石酸拆分酪氨酸乙酯过程中的这一特性, 说明由于二L-酪氨酸乙酯酒石酸盐和二D-酪氨酸乙酯酒石酸盐在乙醇中溶解度都很小, 因此通过酒石酸拆分酪氨酸乙酯的方法不能得到高光学纯度的D-酪氨酸. 在此基础上, 通过形成二酪氨酸甲酯酒石酸盐的方法, 在甲醇中成功地用D-酒石酸拆分制备了D-酪氨酸, 光学纯度99% ee. 相似文献
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Kozma D. Novák Cs. Tomor K. Pokol Gy. Fogassy E. 《Journal of Thermal Analysis and Calorimetry》2000,61(1):45-50
The optical resolution of α-phenylethylamine (1) by 2R,3R-tartaric acid (2) was studied in different solvents, the precipitated
salts were subjected to thermoanalytical measurements and X-ray powder diffraction. The most efficient resolution can be accomplished
by using methanol, the precipitate, an unsolvated salt containing the S-(-)-1⋅2R,3R-(+)-2 salt in abundance, is not a simple
mixture of the diastereoisomeric salt pair, but a new modification. In water, ethanol and acetonitrile a reversed, but less
effective resolution can be accomplished by precipitation of a hydrate which contains the R-(+)-1 in abundance. The precipitates
from water and ethanol also proved to be new modifications. Only the precipitate from acetonitrile is the mixture of the diastereoisomeric
salt pair, which can be expected in fractional crystallization of an eutectic forming diastereoisomeric salt pair. The number
of different modifications found by changing the solvent in case of this particular salt pair seems surprisingly high, but
may occur for other diastereoisomeric salt pairs, too. The existing but not investigated polymorphism can be the explanation
for the sometimes very poor reproducibility of the preparative resolutions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Gaoyuan Ma Prof. Dr. Mukund P. Sibi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11644-11657
Biaryl compounds with axial chirality are very common in synthetic chemistry, especially in catalysis. Axially chiral biaryls are important due to their biological activities and extensive applications in asymmetric catalysis. Thus the development of efficient enantioselective methods for their synthesis has attracted considerable attention. This Minireview discusses the progress made in catalytic kinetic resolution of biaryl compounds and chronicles significant advances made recently in catalytic kinetic resolution of biaryl scaffolds. 相似文献
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Lennartson A Vestergren M Håkansson M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(6):1757-1762
The crystal structures of [Pr(dbm)3H2O] (1), [Sm(dbm)3H2O] (2), and [Er(dbm)3H2O] (3) have been determined (dbm=dibenzoylmethane). They display seven-coordinate propeller-shaped molecules, which are chiral and crystallize as conglomerates in space group R3. Analysis of the crystal structures reveals supramolecular interactions, including formation of a quadruple helix, which explain how stereochemical information can be transferred between stacks of molecules. A method to quantify the ee in bulk samples of stereochemically labile compounds by using solid-state CD spectroscopy is described. Using this method, it has been shown that compounds 1-3 undergo total spontaneous resolution directly after synthesis, forming a microcrystalline reaction product that is essentially enantiopure. The resolution of bulk quantities of seven-coordinate complexes (without chiral or polydentate ligands) is thus reported for the first time. Because the crystallization starts without seeding, the overall preparation may be regarded as absolute asymmetric synthesis. 相似文献
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利用非对映异构体盐在溶剂中溶解度的不同,以(1S,2R)-1-氨基-2-茚醇(1)为手性拆分剂,拆分四氢糠酸[(RS)-THFA, (RS)-2]获得高光学纯的(S)-2,其结构经1H NMR, 13C NMR和HPLC确证。探究了不同溶剂量和投料比对拆分效果的影响。结果表明较佳拆分条件为:以4-甲基-2-戊酮(3)作溶剂,n[(RS)-2]: n(1)=2.2 : 1,一次拆分得91.7% ee (S)-2;再以n[91.7% ee (S)-2]: n(1)=6 : 5进行二次拆分得99.0% ee (S)-2。拆分剂的回收率提高至92.0%,同时对拆分母液中的非目标对映体成功地进行消旋化,回收率为89.0%,实现了四氢糠酸的循环拆分。 相似文献
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Prof.Dr. Mohammed Enamullah Mohammad Mostafizur Rahman Mohammad Khairul Islam Dr. Dennis Woschko Prof.Dr. Christoph Janiak Prof.Dr. Gennaro Pescitelli 《ChemistryOpen》2022,11(7)
A family of bis[(R or S)‐N‐1‐(Ar)ethylsalicylaldiminato‐κ2N,O]‐Δ/Λ‐zinc(II) {Ar=C6H5 (ZnRL1 or ZnSL1), p‐CH3OC6H4 (ZnRL2 or ZnSL2) and p‐ClC6H4 (ZnRL3 or ZnSL3)} compounds was synthesized and investigated by multiple methods. They feature Λ/Δ‐chirality‐at‐metal induction along the pseudo‐C 2 axis of the molecules. The chirality induction is quantitative in the solid state, explored by X‐ray crystallography and powder X‐ray diffraction (PXRD), where R or S‐ligated complexes diastereoselectively yield Λ or Δ‐configuration at the metal. On the other hand, Λ and Δ‐diastereomers co‐exist in solution. The Λ⇆Δ equilibrium is solvent‐ and temperature‐dependent. Electronic circular dichroism (ECD) spectra confirm the existence of a diastereomeric excess of Λ‐ZnRL1−3 or Δ‐ZnSL1−3 in solution. DSC analysis reveals thermally induced irreversible phase transformation from a crystalline solid to an isotropic liquid phase. ECD spectra were reproduced by DFT geometry optimizations and time‐dependent DFT (TD‐DFT) calculations, providing ultimate proof of the dominant chirality atmetal in solution. 相似文献
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A. Sobolev R. Zhalubovskis M. C. R. Franssen B. Vigante B. Chekavichus G. Duburs Ae. de Groot 《Chemistry of Heterocyclic Compounds》2004,40(7):931-937
The lipase-catalyzed kinetic resolution of 3-(isobutyryloxy)methyl 4-[2-(difluoromethoxy)phenyl]-2-methyl-5,5-dioxo-1,4-dihydrobenzothieno[3,2-b]pyridine-3-carboxylate has been performed. The most enantioselective reaction (E = 28) was transesterification with n-butanol in water-saturated toluene at 45°C. 相似文献
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Shen Qu Dr. Mark D. Greenhalgh Andrew D. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(11):2816-2823
An operationally simple isothiourea-catalysed acylative kinetic resolution of unprotected 1,1′-biaryl-2,2′-diol derivatives has been developed to allow access to axially chiral compounds in highly enantioenriched form (s values up to 190). Investigation of the reaction scope and limitations provided three key observations: i) the diol motif of the substrate was essential for good conversion and high s values; ii) the use of an α,α-disubstituted mixed anhydride (2,2-diphenylacetic pivalic anhydride) was critical to minimize diacylation and give high selectivity; iii) the presence of substituents in the 3,3′-positions of the diol hindered effective acylation. This final observation was exploited for the highly regioselective acylative kinetic resolution of unsymmetrical biaryl diol substrates bearing a single 3-substituent. Based on the key observations identified, acylation transition state models have been proposed to explain the atropselectivity of this kinetic resolution. 相似文献
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JPC – Journal of Planar Chromatography – Modern TLC - We have investigated resolution of the enantiomers of each member of a group of five pipecoloxylidides. A standard TLC method was... 相似文献
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Michela Lupi Martina Onori Stefano Menichetti Sergio Abbate Giovanna Longhi Caterina Viglianisi 《Molecules (Basel, Switzerland)》2022,27(4)
We have developed an efficient chemical resolution of racemic hydroxy substituted dithia-aza[4]helicenes (DTA[4]H) 1(OH) using enantiopure acids as resolving agents. The better diastereomeric separation was achieved on esters prepared with (1S)-(−)-camphanic acid. Subsequent simple manipulations produced highly optically pure (≥ 99% enantiomeric excess) (P) and (M)-1(OH) in good yields. The role of the position where the chiral auxiliary is inserted (cape- vs. bay-zone) and the structure of the enantiopure acid used on successful resolution are discussed. 相似文献