52019-78-0Relevant articles and documents
Synthesis of cis-1,2-diol-type chiral ligands and their dioxaborinane derivatives: Application for the asymmetric transfer hydrogenation of various ketones and biological evaluation
Kilic, Ahmet,Balci, Tu?ba Ersayan,Arslan, Nevin,Aydemir, Murat,Durap, Feyyaz,Okumu?, Veysi,Tekin, Recep
, (2020/06/10)
Two cis-1,2-diol-type chiral ligands (T1 and T2) and their tri-coordinated chiral dioxaborinane (T(1–2)B(1–2)) and four-coordinated chiral dioxaborinane adducts with 4-tert-butyl pyridine sustained by N → B dati
Efficient synthesis of enantiopure amines from alcohols using resting: E. coli cells and ammonia
Houwman, Joseline A.,Knaus, Tanja,Costa, Magda,Mutti, Francesco G.
supporting information, p. 3846 - 3857 (2019/07/31)
α-Chiral amines are pivotal building blocks for chemical manufacturing. Stereoselective amination of alcohols is receiving increased interest due to its higher atom-efficiency and overall improved environmental footprint compared with other chemocatalytic and biocatalytic methods. We previously developed a hydrogen-borrowing amination by combining an alcohol dehydrogenase (ADH) with an amine dehydrogenase (AmDH) in vitro. Herein, we implemented the ADH-AmDH bioamination in resting Escherichia coli cells for the first time. Different genetic constructs were created and tested in order to obtain balanced expression levels of the dehydrogenase enzymes in E. coli. Using the optimized constructs, the influence of several parameters towards the productivity of the system were investigated such as the intracellular NAD+/NADH redox balance, the cell loading, the survival rate of recombinant E. coli cells, the possible toxicity of the components of the reaction at different concentrations and the influence of different substrates and cosolvents. In particular, the cofactor redox-balance for the bioamination was maintained by the addition of moderate and precise amounts of glucose. Higher concentrations of certain amine products resulted in toxicity and cell death, which could be alleviated by the addition of a co-solvent. Notably, amine formation was consistent using several independently grown E. coli batches. The optimized E. coli/ADH-AmDH strains produced enantiopure amines from the alcohols with up to 80% conversion and a molar productivity up to 15 mM. Practical applicability was demonstrated in a gram-scale biotransformation. In summary, the present E. coli-ADH-AmDH system represents an important advancement towards the development of 'green', efficient and selective biocatalytic processes for the amination of alcohols.
Biocatalytic Racemization Employing TeSADH: Substrate Scope and Organic Solvent Compatibility for Dynamic Kinetic Resolution
Pop?oński, Jaros?aw,Reiter, Tamara,Kroutil, Wolfgang
, p. 763 - 768 (2018/02/27)
Racemization in combination with a kinetic resolution is the base for a dynamic kinetic resolution (DKR). Biocatalytic racemization was successfully performed for a broad scope of sec-alcohols by employing a single alcohol dehydrogenase (ADH) variant from Thermoanaerobacter pseudoethanolicus (formerly T. ethanolicus; TeSADH W110A I86A C295A). The catalyst employed as a lyophilized whole cell preparation or cell free extract, which tolerated various non-water miscible organic solvents under micro-aqueous or two-phase conditions, whereby cyclohexane and n-hexane suited best. Various concepts for combining the enzymatic racemization with an enzymatic kinetic resolution to achieve overall a bis-enzymatic DKR were evaluated. A proof of concept showed a successful DKR with racemization in aqueous phase combined with acylation in the organic phase.
Discrimination of the prochiral hydrogens at the C-2 position of n-alkanes by the methane/ammonia monooxygenase family proteins
Miyaji, Akimitsu,Miyoshi, Teppei,Motokura, Ken,Baba, Toshihide
, p. 8261 - 8270 (2015/08/03)
The selectivity of ammonia monooxygenase from Nitrosomonas europaea (AMO-Ne) for the oxidation of C4-C8n-alkanes to the corresponding alcohol isomers was examined to show the ability of AMO-Ne to recognize the n-alkane orientation within the catalytic site. AMO-Ne in whole cells produces 1- and 2-alcohols from C4-C8n-alkanes, and the regioselectivity is dependent on the length of the carbon chain. 2-Alcohols produced from C4-C7n-alkanes were predominantly either the R- or S-enantiomers, while 2-octanol produced from n-octane was racemic. These results indicate that AMO-Ne can discriminate between the prochiral hydrogens at the C-2 position, with the degree of discrimination varying according to the n-alkane. Compared to the particulate methane monooxygenase (pMMO) of Methylococcus capsulatus (Bath) and that of Methylosinus trichosporium OB3b, AMO-Ne showed a distinct ability to discriminate between the orientation of n-butane and n-pentane in the catalytic site.
Preparation and properties of xerogels obtained by ionic liquid incorporation during the immobilization of lipase by the sol-gel method
Zarcula, Cristina,Corici, Livia,Croitoru, Ramona,Ursoiu, Anca,Peter, Francisc
experimental part, p. 79 - 86 (2010/10/19)
Lipase from Pseudomonas fluorescens (Amano AK) has been immobilized by the sol-gel method using tetramethoxysilane and trimethoxysilanes with alkyl or aryl groups as precursors and ionic liquids as immobilization additives. Room temperature ionic liquids
Phosphorus-bearing axially chiral biaryls by catalytic asymmetric cross-cyclotrimerization and a first application in asymmetric hydrosilylation
Heller, Barbara,Gutnov, Andrey,Fischer, Christine,Drexler, Hans-Joachim,Spannenberg, Anke,Redkin, Dmitry,Sundermann, Corinna,Sundermann, Bernd
, p. 1117 - 1128 (2007/10/03)
A novel and efficient, two-step route to axially chiral biaryls is demonstrated. In a direct asymmetric cross-cyclotrimerization in the presence of a chiral cobalt(I) catalyst, axially chiral biaryls bearing phosphoryl moieties have been prepared, and through indirect evidence the authors have been able to clarify the origin of the stereochemical induction and the nature of the central intermediate in the catalytic cycle. By subsequent reduction of the phosphoryl moiety to the corresponding phosphine, a very efficient and atom-economical approach to chiral systems has been developed. These chiral systems clearly have great potential use as axially chiral monodentate P- or bidentate P,O-ligands, as has been demonstrated by the employment of the novel NAPHEP as a new monodentate acting ligand in an asymmetric hydrosilylation reaction.
A thermodynamic study of the ketoreductase-catalyzed reduction of 2-alkanones in non-aqueous solvents
Tewari, Yadu B.,Schantz, Michele M.,Phinney, Karen W.,Rozzell, J. David
, p. 89 - 96 (2007/10/03)
Equilibrium constants K have been measured for the reactions (2-alkanone + 2-propanol = 2-alkanol + acetone), where 2-alkanone = 2-butanone, 2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone and 2-alkanol = 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol. The solvents used were n-hexane, toluene, methyl tert-butyl ether (MTBE), and supercritical carbon dioxide SCCO 2 (pressure P - 10.0 MPa). The temperature range was T - (288.15 to 308.27) K. Chiral analysis of the reaction products showed that the enzyme used in this study was stereoselective for the 2-octanone reaction system, i.e. only (S)-(+)-2-octanol was formed. For the reactions involving butanone, pentanone, and hexanone, the products were racemic mixtures of the respective (S)-(+)-2-alkanol and the (R)-(-)-2-alkanol. Chiral analysis showed that for the 2-heptanone reaction system, the 2-alkanol product was a mixture of (S)-(+)-2-heptanol and (R)-(-)-2-heptanol, at the respective mole fractions of 0.95 and 0.05. The equilibrium constant for the reaction system involving 2-butanone carried out in n-hexane was measured at several temperatures. For this reaction, the values for the thermodynamic reaction quantities at T= 298. 15 K are: K= 0.838±0.013; the standard molar Gibbs free energy change ΔrgHm° = (0.44±0.040) kJ · mol-1; the standard molar enthalpy change ΔrgHm° = -(1.2±1.7) kJ mol-1, and the standard molar entropy change ΔrgHm° = -(5.5±5.7) J K-1 mol-1. Interestingly, inspection of the values of the equilibrium constants for these reactions carried out in n-hexane, toluene, MTBE, and SCCO2 shows that these values are comparable and have little dependence on the solvent used to carry out the reaction. The values of the equilibrium constants decrease monotonically with increasing value of the number of carbons Nc and trend towards a limiting value of ≈0.30 for Nc > 8. Published by Elsevier Ltd.
New chiral hosts derived from dimeric tartaric acid: Efficient optical resolution of aliphatic alcohols by inclusion complexation
Tanaka, Koichi,Honke, Shinji,Urbanczyk-Lipkowska, Zofia,Toda, Fumio
, p. 3171 - 3176 (2007/10/03)
The novel, chiral, host compounds 8 and 9 were derived from tartaric acid. Inclusion complexation with these host compounds permitted highly efficient resolution of some aliphatic alcohols (10-13). The symmetrical dimer host compound 8 is effective for optical resolution of alcohols 10, 12, and 13 by a combination of enantioselective inclusion complexation and distillation techniques. The unsymmetrical dimer host compound 9 is effective for optical resolution of cyanohydrin 11. The crystal structures of the inclusion complexes were analyzed by X-ray diffraction methods in order to elucidate the mechanism of the efficient chiral recognition in the inclusion crystals.
Enzymatic resolution of alcohols via lipases immobilized in microemulsion-based gels
De Jesus,Rezende,Nascimento
, p. 63 - 66 (2007/10/02)
Lipases immobilized in microemulsion-based gel (MBG) were used in the resolution of racemic alcohols, in a new, convenient method of catalysis in organic solvents which employs small amounts of the enzyme.
Stereochemistry of Aliphatic Carbocations, 14. Alkyl Shifts from Secondary to Primary Carbon Atoms
Kirmse, Wolfgang,Guenther, Bernd-Rainer,Knist, Johannes,Kratz, Sigrid,Loosen, Karin,et al.
, p. 2127 - 2139 (2007/10/02)
Alkyl shifts from secondary to primary carbon atoms have been induced by the nitrous acid deamination of suitable amines (4, 22, 39, 51); they include sequential rearrangements (-CH3,CH3 and -CH3,H).Predominant although incomplete inversion at the migration origin has been observed (Me 70percent, Et 62-64percent, nPr 65percent, iPr 64percent, tBu 55percent).Our results require the intervention of open secondary carbocations which may be preceded by less stable bridged intermediates.
