- New access to enantiopure O,O'-dibenzoyltartaric acid: Resolution of the mixed calcium methoxyacetate by preferential crystallization
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A convenient resolution of racemic O,O'-dibenzoyltartaric acid by preferential crystallization of its mixed calcium salt formed with methoxyacetic acid is described. The separation of the partially prepared salt 2 followed by a subsequent recrystallization results in a simple and effective resolution of the title compound during which pure enantiomers of 1 can be obtained even on a large scale. The crystal structure of the conglomerate forming complex 2 is also reported.
- Elekes, Ferenc,Kovari, Zoltan,Mravik, Andras,Boecskei, Zsolt,Fogassy, Elemer
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Read Online
- Preparation method of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol
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The invention discloses a preparation method of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol. According to the preparation method, DL-1-phenyl-2-(1-pyrrolidyl)-1-acetone is taken as a starting material and subjected to resolution, racemization and reduction, and (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol is prepared. The yield of one-time resolution is higher than 35%, a resolving agent is easy to recover, and the recovery rate is higher than 90%; the racemization process is performed under the slightly alkaline condition, and the racemization yield is higher; the yield of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol obtained through reduction is higher than 85%. The preparation method has the advantages of mild reaction conditions, stable process, high product optical purity, low cost, high production safety and the like.
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Paragraph 0033
(2016/10/31)
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- New chiral zwitterionic phosphorus heterocycles: Synthesis, structure, properties and application as chiral solvating agents
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A family of new chiral zwitterionic phosphorus-containing heterocycles (zPHC) have been derived from methylene-bridged bis(imidazolines). These structures were unambiguously determined, including single-crystal XRD analysis for two compounds. The stability, acid/base and electronic properties of these dipolar phosphorus heterocycles were subsequently investigated. zPHCs can be successfully employed as a new class of chiral solvating agents for the enantiodifferentiation of chiral carboxylic and sulfonic acids by NMR spectroscopy. The stoichiometry and binding constants for the donor-acceptor complexes formed were established by NMR titration methods. A convenient synthetic approach to a new class of chiral zwitterionic phosphorus-containing heterocycles starting from methylene-bridged bis(imidazolines) was designed and executed. Stability and properties of the synthesized compounds were investigated. The applicability of the designed compounds as chiral solvating agents for the determination of the enantiomeric excesses of chiral acids was demonstrated. Copyright
- Sheshenev, Andrey E.,Boltukhina, Ekaterina V.,Grishina, Anastasiya A.,Cisa?ova, Ivana,Lyapkalo, Ilya M.,Hii, King Kuok
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p. 8136 - 8143
(2013/07/27)
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- PROCESS FOR THE RESOLUTION OF (R,S)-NICOTINE
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(R,S)-Nicotine was resolved through diastereomeric salt formation using dibenzoyl-d-tartaric acid and dibenzoyl-l-tartaric acid to obtain enantiomerically pure (S)-nicotine and (R)-nicotine.
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Page/Page column 3
(2012/08/08)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 51
(2010/12/31)
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- Development of new HPLC chiral stationary phases based on native and derivatized cyclofructans
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An unusual class of chiral selectors, cyclofructans, is introduced for the first time as bonded chiral stationary phases. Compared to native cyclofructans (CFs), which have rather limited capabilities as chiral selectors, aliphatic-and aromatic-functionalized CF6s possess unique and very different enantiomeric selectivities. Indeed, they are shown to separate a very broad range of racemic compounds. In particular, aliphatic-derivatized CF6s with a low substitution degree baseline separate all tested chiral primary amines. It appears that partial derivatization on the CF6 molecule disrupts the molecular internal hydrogen bonding, thereby making the core of the molecule more accessible. In contrast, highly aromaticfunctionalized CF6 stationary phases lose most of the enantioselective capabilities toward primary amines, however they gain broad selectivity for most other types of analytes. This class of stationary phases also demonstrates high "loadability" and therefore has great potential for preparative separations. The variations in enantiomeric selectivity often can be correlated with distinct structural features of the selector. The separations occur predominantly in the presence of organic solvents.
- Sun, Ping,Wang, Chunlei,Breitbach, Zachary S.,Zhang, Ying,Armstrong, Daniel W.
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experimental part
p. 10215 - 10226
(2010/05/01)
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- Process for the continuous production of basic cyclic optically active alpha - amino acids
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PCT No. PCT/EP96/04073 Sec. 371 Date Mar. 24, 1998 Sec. 102(e) Date Mar. 24, 1998 PCT Filed Sep. 18, 1996 PCT Pub. No. WO97/12881 PCT Pub. Date Apr. 10, 1997The invention pertains to a process for the continuous production of basic cyclic optically active alpha -amino acids of general formula (I) by continuous racemate splitting via diastereomeric salt pairs with re-racemisation of the residual amino acid or amino acid derivative in the mother liquid with the aid of an optically active acid.
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- Heteroaromatic diphosphines as chiral ligands
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Chiral diphosphines constituted by an aromatic pentatomic biheterocyclic system, suitable to act as chiral ligands, complexes between said diphosophines and transition metals, and their utilization as chiral catalysts in sterocontrolled reactions, such as diastereo- and enantioselective reduction reactions. Process for the preparation of said chiral diphosophines and process for the preparation of said complexes and for their utilization as chiral catalysts in sterocontrolled reactions.
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- Simple resolution of O,O'-dibenzoyltartaric acid by preferential crystallization of its calcium salt-methoxyethanol complex
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The enantiomers of the title compound can be obtained in a simple two-step crystallization procedure starting from the racemate. The compound 2 of the calcium O,O'-dibenzoyl-tartrate formed with two molecules of 2-methoxyethanol exists as a conglomerate, making a simple enantioseparation possible.
- Mravik, Andras,Lepp, Zsolt,Fogassy, Elemer
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p. 2387 - 2390
(2007/10/03)
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- Process for the preparation of L(-)carnitine hydrochloride and of L(-)carnitine inner salt
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The invention refers to a process for the preparation of L(-)carnitine by using dibenzoyl-D(31 )tartaric acid and crystallizating the relative salt at low temperature.
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- Diastereomer salts of phenylalanine and N-acyl derivatives thereof and process for the separation of optically active phenylalanine and N-acyl derivatives thereof
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The present invention relates to the separation of optically active phenylalanine and N-acyl derivatives thereof and novel diastereomer salts of the said compounds. According to the invention a racemic compound of the formula STR1 is reacted with an optically active resolving agent of the formula STR2 in a polar solvent and/or a mixture of solvents comprising at least one apolar solvent and optionally an achiral acid or base, thereafter (a) when using the D-isomer of the resolving agent of the formula II, the crystalline diastereomer salt formed with the L-isomer of the compound of the formula I is separated, or (b) when using the L-isomer of the resolving agent of the formula II, the crystalline diastereomer salt formed with the D-isomer of the compound of the formula I is separated, and the enantiomers of the compound of the formula I from the diastereomer salt or the mother liquor are liberated by the aid of an achiral acid or base and the optically active product is separated in crystalline form.
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