Fast methods of enantiopurity determination for the Soai reaction: Towards a general enantioenrichment detector?

Welch, Christopher J.; Biba, Mirlinda; Sajonz, Peter

doi:10.1002/chir.20336

Cited by 22 publications

(10 citation statements)

References 36 publications

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“…Only the homochiral dimers are catalytically active, while the heterochiral dimer is completely inactive. [205] A minute enantiomeric imbalance in the racemic sample that gives rise to very high final ee values in Soais reaction was attributed to a combination of amplification processes involving both asymmetric autocatalysis and selective precipitation.…”

Section: Methodsmentioning

confidence: 98%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

491

273

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There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

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Section: Methodsmentioning

confidence: 98%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

491

273

View full text Add to dashboard Cite

show abstract

“…6 The Soai reaction has recently been proposed as a general enantioenrichment detection system. 11 Quantitation of nearly racemic compositions is also important in the verification of enantiomeric enrichments caused by physical forces, should they in fact occur. The alignment of dipoles of prochiral molecules parallel or antiparallel to a magnetic field in conjunction with a chiral autocatalytic process has been suggested to cause (a still elusive) enantiomeric bias of a product in an absolute asymmetric reaction.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method

et al. 2007

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Whereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic samples of representative alpha-amino acids were derivatized as N-(O,S)-trifluoroacetyl/ethylesters and analyzed by enantioselective gas chromatography (GC) on fused silica capillaries coated with the chiral stationary phases (CSPs) Chirasil-D-Val, Chirasil-L-Val, and Lipodex E with GC/FID and GC/MS detection. The validation (accuracy and precision) of the determination of the enantiomeric fraction EF of the D-enantiomer in racemic or near-racemic compositions for 10 DL-alpha-amino acids obtained from commercial sources has been carried out. Emphasis is given to DL-tyrosine, the enantiomers of which have recently been claimed to show different crystallization properties. Values of EF obtained from GC measurements using CSPs were compared with those from CE using chiral mobile phase additives. While the precision of the GC method is generally better than 0.08% for all DL-alpha-amino acids studied, accuracy (trueness) of determination of amino acids with polar side chains is poorer than expected from the precision as a result of systematic errors. The accuracy determined relied on measurements on two oppositely configurated CSPs.

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“…Welch et al presented a rapid analysis method (<1 min per sample) of the ee value of the Soai product by using chiral CO 2 -supercritical fluid chromatography. 53 …”

Section: The Soai Reaction As a Qualitative Sensor For Asymmetrymentioning

confidence: 97%

A concise summary of experimental facts about the Soai reaction

et al. 2010

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The Soai reaction amplifies small enantiomeric excesses in a spectacular manner. Being known for 20 years, it has drawn the attention of many scientists in different fields as it is to date the only chemical reaction offering the chance to study the phenomenon of asymmetric autocatalysis in conjunction with high amplification of enantiomeric excess (ee). This mini-review comprises an introduction to the discovery of asymmetric autocatalysis with amplification of ee and a concise summary of published experimental results showing which starting materials and reaction parameters play an important role in this reaction and which influences are understood. It is addressed especially to scientists entering the field of the Soai reaction to get a quick overview of important aspects.

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Fast methods of enantiopurity determination for the Soai reaction: Towards a general enantioenrichment detector?

Cited by 22 publications

References 36 publications

Nonlinear Effects in Asymmetric Catalysis

Nonlinear Effects in Asymmetric Catalysis

Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method

A concise summary of experimental facts about the Soai reaction

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