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    1.6 Peptides and Chirality Effects on the Conformation and the Synthesis of Medicinally Relevant Peptides
    Elsevier eBooks (2012)
    William D. LubellKim BeauregardFelix Polyak
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    Keywords:
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    Tetrahedron Letters (1987)
    Albrecht MannschreckErwin HartmannHans BuchnerDoris Andert
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    Tetrahedron Asymmetry (2013)
    Richard J. LewisMichael A. BernsteinHui‐Fang ChangDavid ChapmanNils Pemberton
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    De‐racemization of Enantiomers versus De‐epimerization of Diastereomers—Classification of Dynamic Kinetic Asymmetric Transformations (DYKAT)
    Chemistry - A European Journal (2008)
    Johannes SteinreiberKurt FaberHerfried Griengl
    The isolation of single stereoisomers from a racemic (or diastereomeric) mixture by enzymatic or chemical resolution techniques goes in hand with the disposal of 50% (racemate) or more (diastereomeric mixtures) of the "undesired" substrate isomer(s). In order to circumvent this drawback, dynamic systems have been developed for the de-racemization of enantiomers and the de-epimerizations of diastereomers. Key strategies within this area are discussed and are classified according to their underlying kinetics, that is, dynamic kinetic resolution (DKR), dynamic kinetic asymmetric transformations (DYKAT), and hybrids between both of them. Finally, two novel types of DYKAT are defined.
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    Resolution of enantiomeric lorazepam and its acyl and O-methyl derivatives and racemization kinetics of lorazepam enantiomers
    Journal of Chromatography A (1990)
    Xiang‐Lin LuShen K. Yang
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    New Opportunities to Improve the Enantiomeric and Diastereomeric Separations
    InTech eBooks (2018)
    Emese PálovicsZsolt SzeleczkyBeáta SzolnokiBosits MiklósElemér Fogassy
    The preparation of single enantiomers (ee ~100%) is one of the most important demands both for industrial practice and research. Actually, the resolution of the racemic compounds still remains the most common method for producing pure enantiomers on a large scale. To obtain the pure enantiomers, it is necessary to find the appropriate conditions and resolving agents. During the separation of diastereomeric mixtures, similar trends can be observed as in course of the distribution of enantiomeric mixtures between phases, because just the presence of one-third chiral compound (namely the resolving agent) is the difference. This chapter presents new observations and establishments about the new opportunities to optimize the separation of chiral mixtures, especially the diastereomeric mixtures.
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    Elsevier eBooks (2022)
    Emese PálovicsDorottya Fruzsina Bánhegyi
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    Resolution of the enantiomers of tetrahydrozoline by chiral HPLC. The racemization of the enantiomers via an imine–enamine tautomerism
    Tetrahedron Asymmetry (1998)
    Salvatore CaccameseGrazia Principato
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    8.6 Physical Separations: Behavior of Structurally Similar Molecules in the Resolution Processes
    Elsevier eBooks (2012)
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    Resolution and stability of oxazepam enantiomers
    Chirality (1992)
    Shen K. YangXiang‐Lin Lu
    Abstract A solvent mixture containing dioxane, acetonitrile, and hexane was found to be suitable as a mobile phase to resolve oxazepam enantiomers by chiral stationary phase high performance liquid chromatography using covalent Pirkle columns. The resolved oxazepam enantiomers in this solvent mixture had a racemization half‐life greater than 3 days at 23°C. When desiccated at 0°C as dried residue, OX enantiomers were stable for at least 50 days with less than 2% racemization. The conditions which stabilized OX enantiomers significantly facilitated the determination of racemization half‐lives of OX enantiomers in a variety of aqueous and nonaqueous solvents and at different temperatures. © 1992 Wiley‐Liss, Inc.
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    Oxazepam
    Residue (chemistry)
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