Enantioselective reduction of C=N double bond by chromium(II) complexes of natural amino acids

Micskei, Károly; Holczknecht, Orsolya; Marchis, Valér; Lévai, Albert; Patonay, Tamás; Zucchi, Claudia; Pályi, Gyula

doi:10.1002/chir.20193

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…10 Amplification of one molecule enantiomeric excess in consecutive one-pot Soai reaction cycles to macroscopically significant ees As the starting point the experience of the Debrecen group with the use of Cr(II) complexes in reduction of organic functional groups [127][128][129] was utilized, with the modification, that for N,O-donor ligands we chose pure enantiomers of amino acids. This reducing system was first tested in the reduction of various ketonic substrates [130][131][132], then with ketoximes [133]. In both cases medium to high enantiomeric excesses were found in the products.…”

Section: Toward Designed Soai-type Systems?mentioning

confidence: 99%

Stochastic and empirical models of the absolute asymmetric synthesis by the Soai-autocatalysis

et al. 2015

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Absolute asymmetric synthesis (AAS) is the preparation of pure (or excess of one) enantiomer of a chiral compound from achiral precursor(s) by a chemical reaction, without enantiopure chiral additive and/or without applied asymmetric physical field. Only one well-characterized example of AAS is known today: the Soai-autocatalysis. In an attempt at clarification of the mechanism of this particular reaction we have undertaken empirical and stochastic analysis of several parallel AAS experiments. Our results show that the initial steps of the reaction might be controlled by simple normal distribution ("coin tossing") formalism. Advanced stages of the reaction, however, appear to be of a more complicated nature. Symmetric beta distribution formalism could not be brought into correspondence with the experimental observations. A bimodal beta distribution algorithm provided suitable agreement with the experimental data. The parameters of this bimodal beta function were determined by a Pólya-urn experiment (simulated by computer). Interestingly, parameters of the resulting bimodal beta function give a golden section ratio. These results show, that in this highly interesting autocatalysis two or even perhaps three catalytic cycles are cooperating. An attempt at constructing a "designed" Soai-type reaction system has also been made.

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Section: Toward Designed Soai-type Systems?mentioning

confidence: 99%

Stochastic and empirical models of the absolute asymmetric synthesis by the Soai-autocatalysis

et al. 2015

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“…Simplified models, for bioimitating systems, with biology-related substrates are extensively studied in our Laboratories, in collaboration with the University of Debrecen (Gyarmati et al 1999;Patonay et al 1999;Micskei et al 2003Micskei et al , 2005b. The main message of these studies is, that biology-related ligands (amino acids) can be successfully used as sources of chirality on transition metal templates (Cr(II)), even for the preparation of products of the opposite configuration with respect to the chiral inductor.…”

Section: Living Organisms Under Extraterrestrial Conditionsmentioning

confidence: 99%

Astrobiology and Biological Chirality

Caglioti

Holczknecht

Fujii

et al. 2006

Orig Life Evol Biosph

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The emerging discipline of astrobiology could gain valuable support from research dealing with the problems of biological chirality. The most profitable fields of common interest are: (a) living organisms under extraterrestrial conditions, (b) extraterrestrial signatures of life and (c) origin(s) of biological chirality. These areas of complementary and overlapping fields are analysed on the basis of selected references.

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“…However, reports about the reduction of CN bond have not been as numerous as those about the CO bond. Although several series of chiral compounds such as aluminates [8], hydroborates [9], and transition‐metal complexes [10] modified by using chiral amino acid or amino alcohol have been used as chiral reagents or catalysts to convert CN compounds to the corresponding primary amines [11], and the enantioselectivities of most of these reactions are very low, except some phenone O ‐methyl or O ‐benzyl oximes catalyzed by the oxazaborolidines (up to 2.5 equiv) [12].…”

Section: Introductionmentioning

confidence: 99%

A DFT study of the enantioselective reduction of oxime ethers promoted by chiral spiroborate esters

Qu¹,

Chen²,

Wei³

et al. 2011

Int J of Quantum Chemistry

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Mechanisms of borane reduction of the (E)-acetophenone O-methyl oxime catalyzed by the easily prepared and stable spiroborate ester 1, derived from diphenylvalinol has been reported for the first time using density functional theory. Two reaction pathways are investigated at the B3LYP/6-31G(d,p) level of theory. The calculated results reveal that this reaction is accomplished via four steps. All the reactants, products, transition states, and intermediates have been optimized at the B3LYP/6-31G (d,p) level. The analysis of these results reveals that one pathway is more energetically favorable than the other, and its associated product is in good agreement with the experimental result. The solvent effect has been further considered at the B3LYP/6-31G(d,p) level in the solvent THF using the PCM model, and the results indicate that it has no great influence on the enantioselectivity of this reduction. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012National Natural Science Foundation of China [20972130, 21072178]; Henan Province (Innovation Specialist Projects

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Enantioselective reduction of C=N double bond by chromium(II) complexes of natural amino acids

Abstract: Asymmetric reduction of oximes was performed by chromium(II) complexes of natural amino acids in aqueous phase or in H(2)O/DMF (1:1) solvent. Medium-to-quantitative chemoselectivity (54% to >95%) and low-to-medium enantioselectivity (5-50% ee) were found.

Cited by 8 publications

References 22 publications

Stochastic and empirical models of the absolute asymmetric synthesis by the Soai-autocatalysis

Stochastic and empirical models of the absolute asymmetric synthesis by the Soai-autocatalysis

Astrobiology and Biological Chirality

A DFT study of the enantioselective reduction of oxime ethers promoted by chiral spiroborate esters

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