Crystallization-Induced Diastereomer Transformations

Brands, Karel M. J.; Davies, Antony J.

doi:10.1021/cr0406864

Cited by 186 publications

(157 citation statements)

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“…Paradoxically, the "chiral amnesia" induced by solution racemization provides the driving force for the evolution of solid-phase single chirality. 6,10 Crystallization-induced transformations of conglomerates as a route to chiral purification is practiced extensively for diastereomers that epimerize in solution, 20 taking advantage of a difference in solubility. Our results stand in striking contrast to Dimroth's principle, which although applied today primarily to the separation of diastereomers, was originally formulated for the general case of coupled physical and chemical equilibria.…”

mentioning

confidence: 99%

Emergence of a Single Solid Chiral State from a Nearly Racemic Amino Acid Derivative

et al. 2008

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mentioning

confidence: 99%

Emergence of a Single Solid Chiral State from a Nearly Racemic Amino Acid Derivative

et al. 2008

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“…Deracemization of oily racemic nicotinamides with a basic group was examined by dynamic salt formation with enantiopure acids such as dibenzoyltartaric acid (DBTA), based on the fact that chiral materials tend to crystallize in chiral fashion [34,47,48]. Dynamic racemization through the formation of crystalline salts achieves effective deracemization of the racemic base to give optically active salts.…”

Section: Resultsmentioning

confidence: 99%

Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA)

et al. 2013

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Dynamic atroposelective resolution of chiral salts derived from oily racemic nicotinamides and enantiopure dibenzoyltartaric acid (DBTA) was achieved by crystallization. The absolute structures of the axial chiral nicotinamides were determined by X-ray structural analysis. The chirality could be controlled by the selection of enantiopure DBTA as a chiral auxiliary. The axial chirality generated by dynamic salt formation was retained for a long period after dissolving the chiral salt in solution even after removal of the chiral acid. The rate of racemization of nicotinamides could be controlled based on the temperature and solvent properties, and that of the salts was prolonged compared to free nicotinamides, as the molecular structure of the pyridinium ion in the salts was different from that of acid-free nicotinamides.

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“…16,17 The resolution of enantiomers has been performed by preferential crystallisation, [241][242][243][244][245] diastereomer crystallisation, [245][246][247] kinetic and dynamic kinetic resolutions. For both reaction types, kinetic and dynamic kinetic resolution, a basic criterion has to be fulfilled; thus, in order to obtain any resolution at all, the reaction rate (Figure 12) of one enantiomer has to be much faster than that of the other, i.e.…”

Section: Kinetic and Dynamic Kinetic Resolution-a Biocatalytic Perspementioning

confidence: 99%

Recent trends in whole cell and isolated enzymes in enantioselective synthesis

Milner¹,

Maguire²

2012

Arkivoc

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Modern synthetic organic chemistry has experienced an enormous growth in biocatalytic methodologies; enzymatic transformations and whole cell bioconversions have become generally accepted synthetic tools for asymmetric synthesis. This review details an overview of the latest achievements in biocatalytic methodologies for the synthesis of enantiopure compounds with a particular focus on chemoenzymatic synthesis in non-aqueous media, immobilisation technology and dynamic kinetic resolution. Furthermore, recent advances in ketoreductase technology and their applications are also presented.Keywords: Biocatalysis, kinetic and dynamic kinetic resolution, Baker's yeast, ketoreductases General IntroductionAsymmetric synthesis is the preferential formation of one stereoisomer of a chiral target compound to another; when scientists at GlaxoSmithKline, AstraZeneca and Pfizer 1 examined 128 syntheses from their companies, they found as many as half of the drug compounds made by their process research and development groups are not only chiral but also contain an average of two chiral centres each. 2In 2006 just 25 % were derived from the chiral pool and over 50 % employed chiral technologies. 1In order to meet regulatory requirements enantiomeric purities of 99.5 % were deemed necessary by the FDA. 3 This is one of the biggest challenges which face chemists today, primarily due to the recognition of the fact that different enantiomers of the same compound can interact differently in biological systems. As a consequence, the production of single enantiomers instead of racemic mixtures has become an important process in the pharmaceutical and agrochemical industry. Several routes can lead to the desired enantiomer including transition metal-, [4][5][6] organo-5,7-10 and bio-catalysis [11][12][13][14][15] and these have been thoroughly reviewed in the literature. 16,17 2. Biocatalysis IntroductionBiocatalysis involves the use of enzymes or whole cells (containing the desired enzyme or enzyme system) as catalysts for chemical reactions. A timeline of historic events in biocatalysis and biotechnology is outlined in Table 1. [18][19][20] Reviews and Accounts Novel methodologies for discovering industrial enzymes based on genomic sequencing and phage display (discussed further in Section 1.3), 21,22 as well as highly effective optimisation tools based on chemical, physical and molecular biology approaches, 23 have improved the access to biocatalysts, increased their stability, and radically broadened their specificity. 24This greater availability of catalysts with superior qualities including the use of new bioengineering tools contributed significantly to the development of new industrial processes. Biocatalytic methodologies for organic synthesis were outlined by Woodley et al. in three categories: established, emerging and expanding chemistries as depicted in Figure 1. 25 Enzyme classesBy the late 1950s it had become evident that the nomenclature of enzymes without any guiding authority, in a period when the...

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Crystallization-Induced Diastereomer Transformations

Cited by 186 publications

References 163 publications

Emergence of a Single Solid Chiral State from a Nearly Racemic Amino Acid Derivative

Emergence of a Single Solid Chiral State from a Nearly Racemic Amino Acid Derivative

Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA)

Recent trends in whole cell and isolated enzymes in enantioselective synthesis

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