Enantioselective reduction of prochiral ketones by chromium(II) amino acid complexes

Micskei, Károly; Hajdu, Csongor; Wessjohann, Ludger A.; Mercs, László; Kiss‐Szikszai, Attila; Patonay, Tamás

doi:10.1016/j.tetasy.2004.04.017

Cited by 22 publications

(11 citation statements)

References 74 publications

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“…Recently, we have applied successfully chromium(II) acetate to reduce prochiral ketones into alcohols and this reduction could be performed with moderate-to-good enantioselectivity in the presence of α-amino acids. 29 The same reducing system was also used for the enantioselective reduction of C=N double bonds. 30,31 LVT metal ions such as tin(II), iron(II) and chromium(II)…”

Section: Methodsmentioning

confidence: 99%

α-Azido ketones, Part 6. Reduction of acyclic and cyclic α-azido ketones into α-amino ketones: old problems and new solutions

Patonay¹,

Micskei²,

Juhász-Tóth³

et al. 2009

Arkivoc

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Comparative experiments on the selective reduction of α-azido ketones to α-amino ketones revealed that tin(II) chloride reduction followed by immediate protection with Boc group is the method of choice. This methodology proved to be useful for more complex substrates, too. Chromium(II) acetate also resulted in the desired products but in lower yields due to a competitive deazidation procedure. A mechanism to explain this deazidation was suggested.

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Section: Methodsmentioning

confidence: 99%

α-Azido ketones, Part 6. Reduction of acyclic and cyclic α-azido ketones into α-amino ketones: old problems and new solutions

Patonay¹,

Micskei²,

Juhász-Tóth³

et al. 2009

Arkivoc

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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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“…[15] The reduction of acetophenone, substituted acetophenones, and other aryl ketones was accomplished with 2-azetidinecarboxylic acid, 2-piperidinecarboxylic acid, proline, and alanine; good rates and selectivities up to 86 % ee were reported. [17] Natural amino acids (His, Leu, Lys, Phe, Trp, Ala, Asp, Glu, Pro, Val, Asp) were tested as the source of chiral information in experiments conducted with media containing a high percentage of water. Ruthenium complexes based on proline-derived amides were further designed for the asymmetric hydride-transfer reduction of substituted acetophenones, although in organic solvents.…”

Section: Reduction Of Prochiral Substratesmentioning

confidence: 99%

Catalysts Based on Amino Acids for Asymmetric Reactions in Water

2009

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Asymmetric organometallic and organocatalytic processes in aqueous systems are currently of great interest. A few years ago, only a few practitioners studied the subject; now organic reactions in water have become one of the most exciting research areas. The quest to identify water-compatible catalysts has evoked an intense search for new possibilities. Following nature's lead, the application of amino acids as sources of chiral information seems particularly promising for aqueous systems. Herein we provide an overview of very recent advances in the area of asymmetric catalysis in water with amino acids and their derivatives as effective catalysts or essential components of catalysts.

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Enantioselective reduction of prochiral ketones by chromium(II) amino acid complexes

Cited by 22 publications

References 74 publications

α-Azido ketones, Part 6. Reduction of acyclic and cyclic α-azido ketones into α-amino ketones: old problems and new solutions

α-Azido ketones, Part 6. Reduction of acyclic and cyclic α-azido ketones into α-amino ketones: old problems and new solutions

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

Catalysts Based on Amino Acids for Asymmetric Reactions in Water

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