- Difficult substrates in the R-hydroxynitrile lyase catalyzed hydrocyanation reaction: Application of the mass transfer limitation principle in a two-phase system
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The application of a number of new and/or difficult substrates in the catalyzed hydrocyanation reaction by R-hydroxynitrile lyase from almonds is described. By using an aqueous-organic two-phase system and increasing the rate of the enzymatic reaction relative to the mass transfer rate, the enantiomeric purity was improved. By fine tuning the reaction parameters (temperature, pH, and the amount of enzyme) the hydrocyanation reaction was optimized for all substrates. The general principles described here can also be applied to optimize the reaction conditions for other substrates.
- Gerrits, Pieter J.,Marcus, Jan,Birikaki, Lemonia,Van der Gen, Arne
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- Enzyme-Catalysed Synthesis of Optically Active Aliphatic Cyanohydrins
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The enantioselective preparation of aliphatic (R)-cyanohydrins was studied using powdered almond meal, a rich source of mandelonitrile lyase, as a catalyst in organic solvent.The feasibility of powdered almond meal as a catalyst was compared to that of a purified enzyme preparation.
- Huuhtanen, Tuomas T.,Kanerva, Liisa T.
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- Enzymatic Resolution of Optically Active Aliphatic Cyanohydrins
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Enantioselective acylation of cyanohydrins 1a-9a by PPL catalysis and deacylation of propionates 1b-9b by CCL catalysis in toluene from good (E 15-20) to excellent (E >30) enantioselectivity.A solvent has a clear effect on enzymatic enantioselectivity.
- Kanerva, Liisa T.,Kiljunen, Eero,Huuhtanen, Tuomas T.
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- High-Throughput Preparation of Optically Active Cyanohydrins Mediated by Lipases
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Cyanohydrins are versatile compounds with high applicability in organic synthesis; they are used as starting materials for the synthesis of other chemical targets with high industrial added value. Lipase-mediated kinetic resolution reactions are a promising route for the synthesis of optically active cyanohydrins. These reactions can be carried out through the acylation of cyanohydrins or the deacylation of cyanohydrin esters, with different biocatalysts and under different reaction conditions. Unfortunately, depending on the substrate structure, long reaction times can be required to achieve suitable enantiomeric excesses. In this context, we present a high-throughput protocol for the production of optically active cyanohydrins in continuous-flow mode. The products were obtained with moderate to good enantioselectivity (E values from 8 up to >200) and with productivity values from 2.4 to 8.7 times higher in continuous-flow mode than in batch mode. Moreover, the reaction times were reduced from hours in batch mode to minutes in continuous-flow mode.
- Thomas, Juliana Christina,Aggio, Bruno Bernardi,Marques de Oliveira, Alfredo Ricardo,Piovan, Leandro
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p. 5964 - 5970
(2016/12/26)
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- A simple separation method for (S)-hydroxynitrile lyase from cassava and its application in asymmetric cyanohydrination
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Using an acetone precipitation method, crude (S)-hydroxynitrile lyase [(S)-MeHNL] was separated from Munihot esculenta (cassava) leaves, and used directly as biocatalyst to catalyze asymmetric cyanohydrination and produce cyanohydrins with enantiomeric purities (≥90% ee) significantly greater than those previously reported. The use of a water/i-Pr2O system with an enzyme, NaCN, and appropriate amounts of acetic acid is crucial in improving the stereoselectivity of cyanohydrin formation by minimizing the non-enzymatic reaction and the racemization of the chiral products. The proposed isolation method for crude (S)-MeHNL has a high value because of its simplicity, and low cost as well as the high activity of the crude (S)-MeHNL.
- Zheng, Zubiao,Zi, Yan,Li, Zhongzhou,Zou, Xinzhuo
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p. 434 - 439
(2013/06/27)
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- Total synthesis of stagonolide B
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Asymmetric total synthesis of nonenolide stagonolide-B has been presented in this Letter. The main highlight of our synthetic strategy is the application of hydroxynitrile lyase (ParsHNL) mediated asymmetric synthesis of cyanohydrin, Sharpless asymmetric dihydroxylation, cross metathesis (CM) reaction, stereoselective Keck allylation reaction and Yamaguchi macrolactonization at a late stage enables us to achieve the synthesis of the target molecule in an efficient way.
- Das, Tapas,Mahapatra, Tridib,Nanda, Samik
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experimental part
p. 1186 - 1189
(2012/03/26)
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- Stereoselective synthesis of β-amino-γ-butyrolactones
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A novel synthesis of optically active β-amino-γ-butyrolactones is described. O-Silylated (R)-cyanohydrins (R)-3 (derived from aldehydes 1 by (R)-hydroxynitrile lyase ((R)-PaHNL)-catalyzed addition of HCN) were reacted with allyl Grignard to give amino alc
- Roos, Juergen,Effenberger, Franz
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p. 1855 - 1862
(2007/10/03)
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- Stereoselective substitution of (R)-2-(sulfonyloxy)nitriles with sulfur nucleophiles
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Optically active 2-(4-toluenesulfonyloxy)-and (4- nitrobenzenesulfonyloxy)nitriles (R)-3 and (R)-4, which were obtained from (R)-cyanohydrins (R)-2 by sulfonylation, react with sulfur nucleophiles such as potassium thioacetate, potassium ethylxanthogenate, potassium thiocyanate, as well as thioalcohols and thiophenol in a typical S(N02 manner to give the (S)-2-sulfanyl nitriles (S)-7-9 and (S)-11-13 in good chemical yields and enantiomeric excesses. Even (R)-2-methyl-2-(methanesulfonyloxy)hexanenitrile (R)-6, derived from ketone cyanohydrin (R)-5, reacts with potassium thioacetate to yield (S)-2-acetylthio-2-methylhexanenitrile (S)-10 with 97% ee.
- Effenberger, Franz,Gaupp, Sebastian
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p. 1765 - 1775
(2007/10/03)
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- Approach to (R)- and (S)-ketone cyanohydrins using almond and apple meal as the source of (R)-oxynitrilase
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The synthesis of aliphatic and aromatic (R)-ketone cyanohydrins through the addition of hydrogen cyanide to the corresponding ketones and the synthesis of the (S)-enantiomers through the kinetic resolution of racemic ketone cyanohydrins has been studied in the presence of almond or apple meal. Substrate tolerance of the (R)-oxynitrilases towards ketones (R1R2C=O) is highly restricted compared to that of structurally similar aldehydes, reactivity following the order of H>Me>>Et for R2. In the case of aromatic methyl ketones reactivity difference (C6H5>>p-Me-C6H4 for R1) is notable.
- Kiljunen, Eero,Kanerva, Liisa T.
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p. 1551 - 1557
(2007/10/03)
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- Novel (R)-oxynitrilase sources for the synthesis of (R)-cyanohydrins in diisopropyl ether
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Apple, apricot, cherry and plum meal were prepared from the seeds or kernels of mature garden fruits. The preparations as well as almond meal were used as the source of (R)-oxynitrilase for the synthesis of aliphatic and aromatic cyanohydrins in diisoprop
- Kiljunen, Eero,Kanerva, Liisa T.
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p. 1225 - 1234
(2007/10/03)
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- Asymmetric synthesis of tetronic acids by Blaise reaction of protected optically active cyanohydrins
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An asymmetric synthesis of tetronic acids is described, involving the Blaise reaction of Reformatsky reagents with silyl-protected optically active cyanohydrins, which were prepared by an enzyme-catalysed method.
- Duffield, Jonathan J.,Regan, Andrew C.
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p. 663 - 666
(2007/10/03)
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- Method of preparing optically active alcohols which consist substantially or entirely of one enantiomer
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The invention relates to a method of preparing optically active alcohols which consist substantially (at least 75% e.e.) or entirely of one enantiomer of formula 4 STR1 wherein R and A are as defined therein. The method comprises, which maintaining enantiomeric excess, converting an optically active cyanohydrin of formula 1 STR2 into optically active protected cyanohydrin of formula 2 STR3 converting the protected cyanohydrin of formula 2 into an optically active compound of formula 3 STR4 removing the protecting group B.
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- Enzyme-Catalyzed Reactions, 15. - Preparation of (R)-2-(Sulfonyloxy)nitriles and their Reactions with Acetates - Inversion of the Configuration of Optically Active Cyanohydrins
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2-(Sulfonyloxy)nitriles (R)-6,7,8 are obtained in high optical purity from the respective cyanohydrins (R)-2 by sulfonylation with methanesulfonyl chloride (3), toluenesulfonyl chloride (4), and trifluoromethanesulfonic anhydride (5), respectively.In cont
- Effenberger, Franz,Stelzer, Uwe
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p. 779 - 786
(2007/10/02)
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- Aliphatic (S)-Cyanohydrins by Enzyme Catalyzed Synthesis
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The enzyme catalyzed synthesis of aliphatic (S)-cyanohydrins has been accomplished for the first time by application of a hydroxynitrile lyase from leaves of Hevea brasiliensis.The optical purities of (S)-cyanohydrins obtained are in a range between 60 - 97percent.
- Klempier, Norbert,Griengl, Herfried,Hayn, Marianne
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p. 4769 - 4772
(2007/10/02)
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- Synthesis of optically active cyanohydrins using almond meal
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Asymmetric hydrocyanation of aldehydes was accomplished using almond meal, containing the enzyme oxynitrilase. Optically active cyanohydrins with high levels of enantiomeric purity were obtained following a simple procedure.
- Zandbergen,Van der Linden,Brussee,Van der Gen
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p. 1387 - 1391
(2007/10/02)
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- Enzyme-Catalyzed Reactions, 7. - Enantioselective Esterification of Racemic Cyanohydrins and Enantioselective Hydrolysis or Transesterification of Cyanohydrin Esters by Lipases
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Pure cyanohydrin enantiomers (S)-1/(R)-1 and their O-acyl derivatives (R)-3/(S)-3 are obtained from three different lipase-catalyzed reactions: (i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective ac
- Effenberger, Franz,Gutterer, Beate,Ziegler, Thomas,Eckhardt, Elisabeth,Aichholz, Reiner
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- A Convenient Route to (R)-α-Hydroxy Carboxylic Acids and (2R)-1-Amino-2-alkanols from (R)-Cyanohydrins
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(R)-Cyanohydrins, prepared in good to excellent yields with high optical purity by enzyme-catalyzed addition of hydrogen cyanide to aldehydes in organic solvents, are hydrolyzed with concentrated hydrochloric acid at ambient temperature, usually in very high yield, without any trace of racemization to give (R)-α-hydroxy carboxylic acids.Likewise, no racemization is observed by direct reduction of the (R)-cyanohydrins with lithium aluminium hydride to give (2R)-1-amino-2-alkanols.
- Ziegler, Thomas,Hoersch, Brigitte,Effenberger, Franz
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p. 575 - 578
(2007/10/02)
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