108-22-5Relevant academic research and scientific papers
Engineering cyclohexanone monooxygenase for the production of methyl propanoate
Van Beek, Hugo L.,Romero, Elvira,Fraaije, Marco W.
, p. 291 - 299 (2017)
A previous study showed that cyclohexanone monooxygenase from Acinetobacter calcoaceticus (AcCHMO) catalyzes the Baeyer-Villiger oxidation of 2-butanone, yielding ethyl acetate and methyl propanoate as products. Methyl propanoate is of industrial interest as a precursor of acrylic plastic. Here, various residues near the substrate and NADP+ binding sites in AcCHMO were subjected to saturation mutagenesis to enhance both the activity on 2-butanone and the regioselectivity toward methyl propanoate. The resulting libraries were screened using whole cell biotransfor-mations, and headspace gas chromatography-mass spectrometry was used to identify improved AcCHMO variants. This revealed that the I491A AcCHMO mutant exhibits a significant improvement over the wild type enzyme in the desired regioselectivity using 2-butanone as a substrate (40% vs 26% methyl propanoate, respectively). Another interesting mutant is the T56S AcCHMO mutant, which exhibits a higher conversion yield (92%) and kcat (0.5 s-1) than wild type AcCHMO (52% and 0.3 s-1, respectively). Interestingly, the uncoupling rate for the T56S AcCHMO mutant is also significantly lower than that for the wild type enzyme. The T56S/I491A double mutant combined the beneficial effects of both mutations leading to higher conversion and improved regioselectivity. This study shows that even for a relatively small aliphatic substrate (2-butanone), catalytic efficiency and regioselectivity can be tuned by structure-inspired enzyme engineering.
Preparation of various enantiomerically pure (benzotriazol-1-yl)- and (benzotriazol-2-yl)-alkan-2-ols
Pchelka, Beata K.,Loupy, Andre,Petit, Alain
, p. 2516 - 2530 (2006)
(S)-(-)-(Benzotriazol-1-yl)- and (S)-(-)-(benzotriazol-2-yl)-alkan-2-ols 7a-9a, 7b-9b and their (R)-(+)-acetates 10a-12a and 10b-12b were prepared in high enantiomeric excess via lipase from Pseudomonas fluorescens (Amano AK) catalyzed enantioselective acetylation of racemic alcohols 4a-6a and 4b-6b with vinyl acetate in tert-butyl methyl ether or toluene at 23 °C. The enantioselectivity of this transformation was dependent on the length of the alkyl chain with E-values ranging from 30 to 57. Several benzotriazole substituted ketones 1a-3a and 1b-3b were synthesized from 1H-benzotriazole and corresponding haloketones. These compounds were stereoselectively reduced with Baker's yeast in water or in organic solvent containing 5% v/v of water at 30 °C to give the (S)-(-)-alcohol. Better stereoselectivity was observed in the kinetic resolution of racemic alcohols 4a-6a and 4b-6b (ee = 69-92% at 44-52% conversion) compared to reduction of corresponding prochiral ketones 1a-3a and 1b-3b with Baker's yeast (ee = 40-67% at 39-89% conversion). Enhanced enantioselectivities were observed at lower temperatures.
Energy-saving efficient isopropenyl acetate synthesis method
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Paragraph 0050-0055, (2017/04/14)
The invention discloses an energy-saving efficient isopropenyl acetate synthesis method which comprises the following steps: (1) feeding acetic acid into a container, performing heating treatment on the acetic acid so as to generate an ethenone gas from the acetic acid in a catalytic cracking manner, introducing the ethenone gas into a cooler; (2) feeding an acetone solution into a mixing dish, simultaneously feeding a catalyst into the mixing dish, mixing, uniformly stirring, pumping the mixed liquid into the cooler by using a metering pump; (3) conveying the mixed gas in the cooler into a synthesis reaction tower, and enabling the mixed gas to generate a reaction gas in the synthesis reaction tower; and (4) condensing the generated reaction gas so as to obtain a coarse product, refining the coarse product, cooling, crystallizing and drying, thereby obtaining a product. According to the energy-saving efficient isopropenyl acetate synthesis method disclosed by the invention, the ethenone gas and the acetone steam are enabled to have homogeneous reaction directly, so that the reaction efficiency is effectively improved, the transfer amount of acetone is greatly reduced, and the comprehensive utilization rate is increased.
Visible-light-mediated α-arylation of enol acetates using aryl diazonium salts
Hering, Thea,Hari, Durga Prasad,Koenig, Burkhard
, p. 10347 - 10352 (2013/01/15)
Visible light mediates efficiently the α-arylation of enol acetates by aryl diazonium salts under mild conditions using [Ru(bpy)3]Cl 2 as a photoredox catalyst. The broad scope of the reaction toward various diazonium salts and enol acetates was explored. The application of this reaction in the concise synthesis of 2-substituted indoles was demonstrated
Highly efficient dynamic kinetic resolution of secondary aromatic alcohols with low-cost and easily available acid resins as racemization catalysts
Cheng, Yongmei,Xu, Gang,Wu, Jianping,Zhang, Chensheng,Yang, Lirong
supporting information; experimental part, p. 2366 - 2369 (2010/06/13)
A new and efficient dynamic kinetic resolution (DKR) process of secondary aromatic alcohols was developed with acid resins as racemization catalysts. Acid resin CD8604 was shown to have excellent racemization activity and good biocompatibility. When employing CD8604 and complex acyl donors as racemization catalyst and acyl donor, respectively, enantiomerically pure aromatic acetate was obtained with excellent yield and ee values through the DKR process. It is noteworthy that the system could be reused more than 10 times with little loss of yield and ee value.
New palladium nanoclusters. Synthesis, structure, and catalytic properties
Stolyarov,Gaugash,Kryukova,Kochubei,Vargaftik,Moiseev
, p. 1194 - 1199 (2007/10/03)
The reduction of palladium(ii) carboxylates Pd3(OCOR) 6 (R = Me, Et, CHMe2, CMe3) with hydrogen in alcohol solutions containing 1,10-phenanthroline (phen) and subsequent oxidation with oxygen gave new palladium nanoclusters, mainly particles with a nearly spherical metal core and an average size of 18 . Based on elemental analysis, NMR, X-ray photoelectron spectroscopy, and EXAFS, nanoclusters were described by the idealized formula Pd147phen32O60(OCOR) 30. The specimens contained up to ～25% smaller 55-atomic Pd clusters with a ～10 metal core. New nanoclusters catalyze hydrogenation of alkynes and alkenes, reduction of nitriles with formic acid, oxidation of aliphatic and benzylic alcohols, oxidative esterification of ethylene and propylene, and disproportionation of benzyl alcohol into toluene and benzaldehyde.
Vinylic, allylic and homoallylic oxidations of alkenes via π- and σ-organopalladium complexes
Kozitsyna, N.Yu.,Vargaftik,Moiseev
, p. 274 - 291 (2007/10/03)
The stoichiometric and catalytic pathways of oxidative esterification of alkenes via intermediate organopalladium complexes are discussed. The oxidation of propylene, hex-1-ene and cyclohexene by PdII acido complexes containing achiral, racemic and chiral carboxylate ligands was first studied in a series of solvents other than acetic acid. Significant changes in the selectivity of the PdII-promoted reaction with changes in the solvent nature and ligand chirality were observed. A way to allylic esters based on low-valence Pd nanoclusters provide highly selective oxidation of acyclic alkenes into allylic esters, whereas cycloalkenes undergo mostly redox disproportionation. The role of π-alkene, σ-alkenyl and π-allyl complexes in the mechanism of the alkene oxidative esterification with PdII complexes and low-valence Pd clusters is discussed.
The effects of the solvent and the ligand chirality on the regioselectivity of alkene oxidative esterification by PdII carboxylates
Kozitsyna,Martens,Stolyarov,Gekhman,Vargaftik,Moiseev
, p. 1673 - 1681 (2007/10/03)
The effects of the solvent and the ligand chirality on the regioselectivity of oxidative esterificanon of propylene and cyclohexene by PdII carboxylates were studied using achiral (MeCO2-, Me2CHCH2CO2-), racemic ((±)-CF3CF2CF2OC*F(CF3) CO2-) and chiral ((S)-(+)-MeC*H(Et)CO2-, (+)-CF3CF2CF2OC*F(CF3)CO2 -) carboxylate ligands. The oxidation of alkenes in aprotic media (CHCl3, CH2C12, CO2, THF) affords mainly allylic esters (in the case of cyclohexene also homoallylic esters) and the oxidative esterification at the vinylic position is absent. In weakly solvating media (CHCl3, CH2Cl2) the regioselectivity of cyclohexene oxidation (the allyl to homoallyl ratio) increases substantially on going from achiral or racemic acido ligands to chiral acido ligands. In a more donor medium (THF) the ligand chirality effect almost vanishes. The effects of the ligand chirality and the nature of the solvent on the mechanism of alkene oxidation by PdII complexes are discussed.
Formation of Glycol Monoacetates in the Oxidation of Olefins Catalyzed by Metal Nitro Complexes: Mono- vs. Bimetallic System
Mares, Frank,Diamond, Steven E.,Regina, Francis J.,Solar, Jeffrey P.
, p. 3545 - 3552 (2007/10/02)
The oxidation of terminal olefins by bis(acetonitrile)chloronitropalladium(II) (1) in acetic acid leads to a mixture of glycol monoacetate isomers as the main products.Various amounts of ketones and unsaturated acetates are also formed.The rate of formation and the yield of glycol monoacetate decrease with increasing chain length.Cyclic olefins yield no glycol monoacetates.Replacement of acetic acid by stronger or sterically hindered carboxylic acids completely eliminates the formation of glycol monocarboxylates.Introduction of oxygen converts this stoichiometric reaction into a catalytic system.Our studies, including those carried out with complex 1 labeled with 18O in the nitro ligand, suggest that the glycol monoacetates and most of the ketones are the product of oxygen atom transfer from the nitro group, while the unsaturated acetates are the result of a Wacker-type reaction.In the glycol monoacetate, the 18O label is found exclusively in the acetate group.A mechanism which is in agreement with the above observations as well as a comparison of the above reaction with the oxidation of olefins by nitrate ions in the presence of palladium(II) salts is offered.The formation of glycol monoacetates in the monometallic system represented by complex 1 is to be compared with the results obtained in the bimetallic systems consisting of a combination of py(TPP)CoNO2 and either (CH3CN)2PdCl2 or Pd(OAc)2.In the latter systems, ketones or vinyl acetates are found as the predominant products.This fact underlines the difference between the mono- and bimetallic systems and strongly argues against alternative mechanisms involving nitro group transfer from cobalt to palladium before the olefin oxidation takes place.Additional evidence underlining the difference between these two systems is presented.
