- Development of dynamic kinetic resolution on large scale for (±)-1-phenylethylamine
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Candida antarctica lipase B (CALB) and racemization catalyst 4 were combined in the dynamic kinetic resolution (DKR) of (±)-1- phenylethylamine (1). Several reaction parameters have been investigated to modify the method for application on multigram scale
- Thalen, Lisa K.,Baeckvall
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- Isopropyl 2-ethoxyacetate—an efficient acylating agent for lipase-catalyzed kinetic resolution of amines in batch and continuous-flow modes
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Productivity [conversion (c) and specific reaction rate (rbatchor rflow)] and enantiomer selectivity [enantiomeric ratio (E) and enantiomeric excess (ee) of the products] of ethyl and isopropyl esters of acetic, 2-methoxyacetic and 2-ethoxyacetic acids as acylating agents were compared in the N-acylation of (±)-1-phenylethanamine rac-1 catalyzed by variously immobilized forms of Candida antarctica lipase B (CaLB) using shake flasks and continuous-flow reactors. The effect of the temperature in the 0–80 °C range on productivity and enantiomer selectivity in KRs of rac-1 was investigated with the isopropyl esters in continuous-flow mode using CaLB-filled minireactors. Isopropyl 2-ethoxyacetate surpassed the performance of ethyl 2-methoxyacetate in terms of both productivity (1.9–2.9 times higher rate in batch mode) and enantiomeric selectivity (ee(R)-amide>99.9% compared to 99.8%) providing at 40 °C high volumetric productivity (2.22 kg L?1h?1), specific reaction rate and enantiomeric excess (rflow=783 μmol min?1g?1, ee(R)-2c>99.9%).
- Oláh, Márk,Boros, Zoltán,Hornyánszky, Gábor,Poppe, László
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- Positional immobilization of Pd nanoparticles and enzymes in hierarchical yolk-shell@shell nanoreactors for tandem catalysis
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A hierarchical yolk-shell@shell nanoreactor that spatially positioned Pd nanoparticles and the CALB enzyme in separated domains is constructed, and served as an efficient bifunctional catalyst for the one-pot dynamic kinetic resolution (DKR) reaction of 1
- Zhang, Xiaoming,Jing, Lingyan,Chang, Fangfang,Chen, Shuai,Yang, Hengquan,Yang, Qihua
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- Ammonium formate as a green hydrogen source for clean semi-continuous enzymatic dynamic kinetic resolution of (+/-)-α-methylbenzylamine
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The chemoenzymatic dynamic kinetic resolution of (+/-)-α- methylbenzylamine under continuous flow conditions in the presence of Pd/BaSO4 as racemization catalyst and ammonium formate as reductant is described. Under the conditions good conversions and excellent enantiomeric excess are reported. This journal is the Partner Organisations 2014.
- De Miranda, Amanda S.,De Souza, Rodrigo O. M. A.,Miranda, Leandro S. M.
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- Modification of supported Pd catalysts by alkalic salts in the selective racemization and dynamic kinetic resolution of primary amines
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Supported Pd nanoparticles (PdNPs) were modified with various alkalic salts by incipient wetness impregnation method. The effect of the salts on the catalytic activity and selectivity behavior of Pd catalysts for the racemization of (S)-1-phenylethylamine was investigated. The presence of alkalic salts can greatly enhance the selectivity of Pd catalysts, without significantly decreasing the catalytic activity. This modification method is suitable for PdNPs supported on various supports, such as micro/mesoporous silica and activated carbon. Combined with the immobilized lipases (Novozyme 435), this catalyst system can efficiently catalyze the dynamic kinetic resolution (DKR) of 1-phenylethylamine with yield and enantioselectivity up to 97% and 99%, respectively. The Royal Society of Chemistry.
- Jin, Qianru,Jia, Guoqing,Zhang, Yanmei,Li, Can
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- Optically active amines via lipase-catalyzed methoxyacetylation
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Racemic amines can be efficiently resolved using ethylmethoxyacetate as acylating agent in a lipase-catalyzed reaction. The reaction of 1-phenyethylamine with ethylmethoxyacetate in the presence of a lipase from Burkholderia plantarii is presented. Excellent yields and selectivity and minimal amount of enzyme characterize this new process. Johann Ambrosius Barth 1997.
- Balkenhohl, Friedhelm,Ditrich, Klaus,Hauer, Bernhard,Ladner, Wolfgang
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- Fast racemization and dynamic kinetic resolution of primary benzyl amines
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We prepared a Pd nanocatalyst (average diameter of Pd nanoparticles = 1.73 nm) displaying a remarkable activity for the racemization and dynamic kinetic resolution (DKR) of 1-methylbenzylamine. It was eight times more active than the previous best. The DKR of 1-methylbenzylamine with the Pd nanocatalyst (2 mol %) in the presence of a thermostable lipase (Novozym 435) was complete in 6 h at 70 °C. The DKRs of other benzyl amines also proceeded to completion in 6 h under similar conditions except the amount of Pd nanocatalyst.
- Kim, Yunwoong,Park, Jaiwook,Kim, Mahn-Joo
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- Co-immobilization of an enzyme and a metal into the compartments of mesoporous silica for cooperative tandem catalysis: An artificial metalloenzyme
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Surpassing nature: A hybrid catalyst in which Candida antarctica lipase B and a nanopalladium species are co-immobilized into the compartments of mesoporous silica is presented. The metal nanoparticles and the enzyme are in close proximity to one another in the cavities of the support. The catalyst mimics a metalloenzyme and was used for dynamic kinetic resolution of a primary amine in high yield and excellent enantioselectivity. Copyright
- Engstroem, Karin,Johnston, Eric V.,Verho, Oscar,Gustafson, Karl P. J.,Shakeri, Mozaffar,Tai, Cheuk-Wai,Baeckvall, Jan-E.
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- Combining Pd nanoparticles on MOFs with cross-linked enzyme aggregates of lipase as powerful chemoenzymatic platform for one-pot dynamic kinetic resolution of amines
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Acquisition of chiral amines is a very important item in scientific research. Chemoenzymatic catalyst combination of Pd nanoparticles supported on the external surface of the ethylenediamine-functionalized MIL-101 (Pd?ED-MIL-101) with layered cross-linked
- Wang, Meng,Wang, Xiaoxu,Feng, Bo,Li, Yuanhua,Han, Xinchen,Lan, Zijie,Gu, Huajun,Sun, Huamin,Shi, Meng,Li, Hexing,Li, Hui
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- New Biosilified Pd-lipase hybrid biocatalysts for dynamic resolution of amines
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In this work lipase CaLB was immobilized on functionalized Pd-SiO2 nanoparticles in order to simplify the DKR of α-methylbenzylamine. Hybrid biocatalysts showed immobilization efficiencies of 82%, 80% and 76% when containing 1, 5 and 10% of Pd respectively. On DKR reaction values of ee > 99% and conversion of 82% were found with only 1% of Pd, generating a productivity of 2.21 mg of product h?1 mg of support?1 against 0.76 found by N435. Compared to commercial N435, the novel biocatalysts showed protein loads about 15-fold lower and higher activity, demonstrating competitive performances and high industrial applications.
- de Souza, Stefania P.,Le?o, Raquel A.C.,Bassut, Jonathan F.,Leal, Ivana C.R.,Wang, Shuai,Ding, Qiqi,Li, Yingying,Lam, Frank Leung-Yuk,de Souza, Rodrigo O.M.A.,Itabaiana Jr, Ivaldo
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- Synthesis and characterization of a magnetic hybrid catalyst containing lipase and palladium and its application on the dynamic kinetic resolution of amines
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Recent papers estimates that about 40 % of drugs present chiral amines in their structure and their synthesis in a sustainable and cost-competitive way is still a challenge for the industry. Kinetic resolution is one of the most applied method to produce these desired compounds where the association with lipase as a catalyst is a good alternative. However, the use of separate racemization catalyst and enzymes in the reaction medium still limits recovery, recycling and can occasionally be responsible for decreasing in selectivity for the desired product. In this work we proposed the synthesis and characterization of a hybrid magnetic catalyst composed containing lipase CaL B and Pd immobilized on the same recovered nanometric magnetic support for the application on Dynamic Kinetic Resolution of (rac)-1-phenylethylamine both in batch and continuous flow conditions. As results it was possible to achieve 99 % of conversion, with 95 % of selectivity and 93 % of enantiomeric excess after 12 h in batch. For a continuous flow system, it was possible to achieve 95 % of conversion with 71 % of selectivity and ee > 99 % after 60 min of reaction. The hybrid catalyst had around 50?100 nm with nanoparticulated Pd (5?10 nm) on its surface, presented a superparamagnetic behavior without remaining magnetization and 22 emu/g of saturation magnetization.
- Almeida, Rhudson F. O.,Caraballo, Richard,Dalm?nico, Gisele,Ferraz, Clara A.,Finotelli, Priscilla V.,Itabaiana, Ivaldo,Junior, Aldo A. T.,Le?o, Raquel A. C.,Sergio, Gabriella G.,Wojcieszak, Robert,de Souza, Rodrigo O. M. A.,do Nascimento, Marcelo A.
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- Artificial plant cell walls as multi-catalyst systems for enzymatic cooperative asymmetric catalysis in non-aqueous media
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The assembly of cellulose-based artificial plant cell wall (APCW) structures that contain different types of catalysts is a powerful strategy for the development of cascade reactions. Here we disclose an APCW catalytic system containing a lipase enzyme and nanopalladium particles that transform a racemic amine into the corresponding enantiomerically pure amide in high yieldviaa dynamic kinetic resolution.
- B?ckvall, Jan-E.,Córdova, Armando,Deiana, Luca,Naidu, Veluru Ramesh,Rafi, Abdolrahim A.,Tai, Cheuk-Wai
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supporting information
p. 8814 - 8817
(2021/09/07)
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- Mesoporous Core-Shell Nanostructures Bridging Metal and Biocatalyst for Highly Efficient Cascade Reactions
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Mesoporous core-shell structured nanocatalysts with a PdPt bimetallic core and enzyme-immobilized polydopamine (PDA) shell were designed, in which the PDA shell worked as a barrier to position the bimetallic core and enzyme in separated locations. The accessible mesoporous structures of both the core and shell significantly facilitate mass transfer and catalyst utilization, improving the synergistic catalytic abilities in cascade reactions. The obtained bifunctional nanocatalysts enabled efficient two-step one-pot cascade reactions of different types: dynamic kinetic resolution of primary amines in organic solvent with high yield and enantioselectivity (up to 99% yield and 98% ee) and degradation of organophosphate nerve agent in aqueous solution with high rate constant and turnover frequency number values (0.8 min-1 and 20 min-1, respectively).
- Gao, Jing,Gao, Shiqi,Jiang, Yanjun,Liu, Yunting,Ma, Li,Wang, Zihan
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p. 1375 - 1380
(2020/02/06)
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- Co-immobilization of metal and enzyme into hydrophobic nanopores for highly improved chemoenzymatic asymmetric synthesis
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Chemoenzymatic catalysts with hydrophobic nanopores were fabricated by co-immobilizing metal nanoparticles and enzymes into the dendritic organosilica nanoparticles. They demonstrated highly improved catalytic performance in chemoenzymatic asymmetric synthesis of chiral amines and alcohols. The hydrophobic microenvironment proved to be critical to enhanced stability, activity and cascade efficiency. This journal is
- Gao, Liya,Wang, Zihan,Liu, Yunting,Liu, Pengbo,Gao, Shiqi,Gao, Jing,Jiang, Yanjun
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supporting information
p. 13547 - 13550
(2020/11/17)
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- Chemoenzymatic Dynamic Kinetic Resolution of Primary Benzylic Amines using Pd0-CalB CLEA as a Biohybrid Catalyst
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Herein, we report on the use a biohybrid catalyst consisting of palladium nanoparticles immobilized on cross-linked enzyme aggregates of lipase B of Candida antarctica (CalB CLEA) for the dynamic kinetic resolution (DKR) of benzylic amines. A set of amines were demonstrated to undergo an efficient DKR and the recyclability of the catalysts was studied. Extensive efforts to further elucidate the structure of the catalyst are presented.
- Gustafson, Karl P. J.,G?rbe, Tamás,de Gonzalo-Calvo, Gonzalo,Yuan, Ning,Schreiber, Cynthia L.,Shchukarev, Andrey,Tai, Cheuk-Wai,Persson, Ingmar,Zou, Xiaodong,B?ckvall, Jan-E.
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p. 9174 - 9179
(2019/07/04)
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- Optimization of 2-alkoxyacetates as acylating agent for enzymatic kinetic resolution of chiral amines
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In this study, the activity of acetic acid esters modified with electron withdrawing 2-alkoxy-groups was investigated as acylating agent in kinetic resolution (KR) of racemic amines. A homologous series of the isopropyl esters of four 2-alkoxyacetic acids (2-methoxy-, 2-ethoxy-, 2-propoxy- and 2-butoxyacetic acids) were prepared and investigated for enantiomer selective N-acylation, catalyzed by lipase B from Candida antarctica, under batch and continuous-flow conditions. In the first set of experiments, isopropyl 2-propoxyacetate showed the highest effectivity with all of the four racemic amines [(±)-1-phenylethylamine, (±)-4-phenylbutan-2-amine, (±)-heptan-2-amine and (±)-1-methoxypropane-2-amine] in the set enabling excellent conversions (≥46%) and enantiomeric excess values (ee ≥ 99%) with each amines in continuous-flow mode KRs under the optimized reaction conditions. In a second set of experiments, KRs of five additional amines – being substituted derivatives of (±)-1-phenylethylamine – further demonstrated the usefulness of isopropyl 2-propoxyacetate – being the best acylating agent in the first set of KRs – in KRs leading to (R)-N-propoxyacetamides with high ee values (≥99.8%).
- Oláh, Márk,Kovács, Dániel,Katona, Gabriel,Hornyánszky, Gábor,Poppe, László
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p. 3663 - 3670
(2018/06/04)
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- SYNTHESIS OF AMIDES AND AMINES FROM ALDEHYDES OR KETONES BY HETEROGENEOUS METAL CATALYSIS
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This invention concerns the first mild and efficient synthesis of primary amines and amides from aldehydes or ketones using a heterogeneous metal catalystand amine donor. The initial heterogeneous metal- catalyzed reaction between the carbonyl and the amine donor components is followed up with the addition of a suitable acylating agent component in one-pot. Hence, the present invention provides a novel catalytic one-pot three-component synthesis of amides. Moreover, the integration of enzyme catalysis allows for eco-friendly one-pot co-catalytic synthesis ofamides from aldehyde and ketone substrates, respectively. The process can be applied to the co-catalytic one-pot three-component synthesis of capsaicin and its analogues from vanillin or vanillyl alcohol. It can also be applied for asymmetric synthesis. In the present invention, a novel co-catalytic reductive amination/dynamic kinetic resolution (dkr) relay sequence for the asymmetric synthesis of optically active amides from ketones is disclosed. Moreover, implementation of a catalytic reductive amination/kinetic resolution (kr) relay sequence produces the corresponding optically active amide product and optical active primary amine product with the opposite stereochemistry from the starting ketones.
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Page/Page column 23
(2016/07/05)
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- Highly Productive and Enantioselective Enzyme Catalysis under Continuous Supported Liquid–Liquid Conditions Using a Hybrid Monolithic Bioreactor
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Enzyme-containing ionic liquids (ILs) were immobilized in cellulose-2.5-acetate microbeads particles embedded in a porous monolithic polyurethane matrix. This bioreactor was used under continuous liquid-liquid conditions by dissolving the substrates in a nonpolar organic phase immiscible with the ILs, thereby creating a biphasic system. Lipases (candida antarctica lipase B, CALB, candida rugosa lipase, CRL) were used to catalyze the enantioselective transesterification of racemic (R,S)-1-phenylethanol with vinyl butyrate and vinyl acetate, the esterification of (+/-)-2-isopropyl-5-methylcyclohexanol with propionic anhydride and the amidation of (R,S)-1-phenylethylamine with ethyl methoxyacetate. With this unique setup, very high productivities, that is, turnover numbers (TONs) up to 5.1×106 and space-time yields (STYs) up to 28 g product L?1 h?1, exceeding the corresponding values for batch-type reactions by a factor of 3100 and 40, respectively, were achieved while maintaining or even enhancing enantioselectivity compared to batch reactions via kinetic resolution. To our best knowledge, this is the first continuously operated bioreactor using supported liquid-liquid conditions that shows these features in the synthesis of chiral esters and amides.
- Sandig, Bernhard,Buchmeiser, Michael R.
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p. 2917 - 2921
(2016/11/02)
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- Integrated Heterogeneous Metal/Enzymatic Multiple Relay Catalysis for Eco-Friendly and Asymmetric Synthesis
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Organic synthesis is in general performed using stepwise transformations where isolation and purification of key intermediates is often required prior to further reactions. Herein we disclose the concept of integrated heterogeneous metal/enzymatic multiple relay catalysis for eco-friendly and asymmetric synthesis of valuable molecules (e.g., amines and amides) in one-pot using a combination of heterogeneous metal and enzyme catalysts. Here reagents, catalysts, and different conditions can be introduced throughout the one-pot procedure involving multistep catalytic tandem operations. Several novel cocatalytic relay sequences (reductive amination/amidation, aerobic oxidation/reductive amination/amidation, reductive amination/kinetic resolution and reductive amination/dynamic kinetic resolution) were developed. They were next applied to the direct synthesis of various biologically and optically active amines or amides in one-pot from simple aldehydes, ketones, or alcohols, respectively.
- Palo-Nieto, Carlos,Afewerki, Samson,Anderson, Mattias,Tai, Cheuk-Wai,Berglund, Per,Córdova, Armando
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p. 3932 - 3940
(2016/07/06)
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- Catalytic acceptorless dehydrogenations: Ru-Macho catalyzed construction of amides and imines
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A commercially available ruthenium(II) PNP type pincer catalyst (Ru-Macho) promotes formation of amides and imines from alcohols and amines via an acceptorless dehydrogenation pathway. The formation of secondary amides, tertiary amides, and secondary ketimines occurs in yields ranging from 35% to 95%.
- Oldenhuis, Nathan J.,Dong, Vy M.,Guan, Zhibin
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supporting information
p. 4213 - 4218
(2014/06/09)
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- An approach to chemoenzymatic DKR of amines in Soxhlet apparatus Dedicated to Prof. Maria José Calhorda on the occasion of her 65th birthday.
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The coexistence of thermolabile enzyme and metal catalyst for racemization of amines in chemoenzymatic dynamic kinetic resolution, requiring high temperature of operation, is enabled by carrying out the reaction in modified Soxhlet extraction system. Init
- Mavrynsky, Denys,Leino, Reko
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p. 161 - 166
(2014/05/06)
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- Chemoenzymatic dynamic kinetic resolution of primary amines using a recyclable palladium nanoparticle catalyst together with lipases
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A catalyst consisting of palladium nanoparticles supported on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was used in chemoenzymatic dynamic kinetic resolution (DKR) to convert primary amines to amides in high yields and excellent ee's.
- Gustafson, Karl P. J.,Lihammar, Richard,Verho, Oscar,Engstroem, Karin,Baeckvall, Jan-E.
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p. 3747 - 3751
(2014/05/20)
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- Ethyl acetate as an acyl donor in the continuous flow kinetic resolution of (±)-1-phenylethylamine catalyzed by lipases
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The synthesis of chiral amines is still a challenge for organic synthesis since optically pure amines are of great importance for the pharmaceutical and agrochemical industries. Among all the methodologies developed until now, chemoenzymatic dynamic kinetic resolution has proven to be useful for the preparation of enantioenriched primary chiral amines. In our continuous efforts toward the development of a continuous flow process, herein we report our results on the continuous flow kinetic resolution of (±)-1- phenylethylamine leading to the desired products with high enantiomeric ratios (>200) and short residence times (40 minutes) using ethyl acetate as the acyl donor.
- De Miranda, Amanda S.,Miranda, Leandro S. M.,De Souza, Rodrigo O. M. A.
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supporting information
p. 3332 - 3336
(2013/06/05)
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- Solvent-free kinetic resolution of primary amines catalyzed by Candida antarctica lipase B: Effect of immobilization and recycling stability
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Highly enantioselective (E >200) N-acylation of nine racemic primary amines with isopropyl methoxyacetate in the presence of Candida antarctica lipase B (Novozym 435) has been reported to yield the unreacted (S)-amines (ee ≥98%) and produced the (R)-amides (ee ≥95%) at 50% conversion under solvent-free conditions. One of the amines and the acyl donor have been used in an equimolar ratio at room temperature (23 °C). Under the reaction conditions, the reuse stability of Novozym 435 with 1-phenylethylamine (as a model compound) has been shown to be poor while somewhat improved stability has been observed with an in-house prepared sol-gel CAL-B catalyst.
- Paeivioe, Mari,Perkioe, Paeivi,Kanerva, Liisa T.
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experimental part
p. 230 - 236
(2012/06/15)
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- Method for preparing optically active amines
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The present invention relates to a method of preparing optically active amines and chiral amines prepared thereby. The method includes reacting an amine compound, a metal catalyst, a biocatalyst including a lipase, and an acyl donor compound in an organic solvent to obtain a chiral amide compound, and then hydrolyzing the chiral amide compound to obtain a chiral amine.
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Page/Page column 13-14
(2009/09/29)
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- Fully enzymatic resolution of chiral amines: Acylation and deacylation in the presence of Candida antarctica lipase B
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A fully enzymatic methodology for the resolution of chiral amines has been demonstrated. Candida antarctica lipase B (CaLB)-catalyzed acylation with N-methyl-and N-phenylglycine, as well as analogues having the general formula R1-X-CH2CO2R2 (R1 = Me, Ph; X = O, S) afforded the corresponding enantioenriched amides, which were subsequently enzymatically hydrolyzed. Surprisingly, CaLB also proved to be the catalyst of choice for this latter step. The heteroatom in the acyl donor profoundly influences both the enzymatic acylation and deacylation; the O-substituted reagents performed best with regard to enantioselectivity as well as reaction rate in synthesis and hydrolysis.
- Ismail, Hilda,Lau, Rute Madeira,Van Rantwijk, Fred,Sheldon, Roger A.
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experimental part
p. 1511 - 1516
(2009/08/07)
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- Optically active amines by enzyme-catalyzed kinetic resolution
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Chiral amines are resolved by an enzyme-catalyzed kinetic resolution. Key steps are the selective acylation of one enantiomer with isopropyl methoxyacetate, separation of the resulting amide from the unreacted antipode, and finally amide hydrolysis. The p
- Ditrich, Klaus
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experimental part
p. 2283 - 2287
(2009/04/06)
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- Asymmetric reductive acylation of aromatic ketoximes by enzyme-metal cocatalysis
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(Chemical Equation Presented) We have developed an efficient procedure for the asymmetric synthesis of chiral amides from ketoximes. This one-pot procedure employs two different types of catalysts, Pd nanocatalyst and lipase, for three consecutive transfo
- Han, Kiwon,Park, Jaiwook,Kim, Mahn-Joo
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p. 4302 - 4304
(2008/09/20)
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- Microwave-promoted racemization and dynamic kinetic resolution of chiral amines over Pd on alkaline earth supports and lipases
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Microwave irradiation was applied in the racemization and dynamic kinetic resolution of primary benzylic amines. Racemization reactions catalyzed by 5% Pd/BaSO4 and 5% Pd/CaCO3 were faster and more selective when performed under microwave conditions. The use of microwave irradiation stopped the formation of side products, such as secondary amines and ethylbenzene. This was correlated with the selective heating of the metal sites under microwave heating. The influence of the microwave irradiation also was checked in the kinetic resolution; no influence on the activity and enantioselectivity of the immobilized Candida Antarctica Lipase B (Novozym 435) was observed when both conventional and microwave heating were compared. The racemization catalysts were combined in one pot with the biocatalyst Novozym 435 to perform the dynamic kinetic resolution of benzylic amines under microwave irradiation. High yields (up to 88%) of enantiopure amides were obtained in less than 1 h when microwave irradiation was applied.
- Parvulescu, Andrei N.,Van der Eycken, Erik,Jacobs, Pierre A.,De Vos, Dirk E.
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p. 206 - 212
(2008/09/20)
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- Heterogeneous raney nickel and cobalt catalysts for racemization and dynamic kinetic resolution of amines
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Raney metals were studied as heterogeneous catalysts for racemization and dynamic kinetic resolution (DKR) of chiral amines, as an alternative to metals like palladium or ruthenium. Both Raney nickel and cobalt were able to selectively racemize various chiral amines with high selectivity. In the racemization of benzylic primary amines, the minor formation of side products, e.g., secondary amines, can be suppressed by varying the hydrogen pressure. In the racemization of aliphatic amines over Raney catalysts, the selectivity is very high, with the enantiomeric amine as the sole product. DKR of racemic aliphatic amines can be performed with immobilized Candida antarctica lipase B and Raney nickel in one pot; for 2-hexylamine, a yield of 95% of the acetylated amide was achieved, with 97% ee. Attention is devoted to the compatibility of the enzyme and the metal catalyst during the DKR. For benzylic primary amines, a two-pot process is proposed in which the liquid is alternatingly shuttled between two vessels containing the solid racemization catalyst and the biocatalyst. After 4 such cycles, the amide of (R)-1-phenylethylamine was obtained with 94% yield and more than 90% ee.
- Parvulescu, Andrei N.,Jacobs, Pierre A.,De Vos, Dirk E.
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scheme or table
p. 113 - 121
(2009/04/16)
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- Fast DKR of amines using isopropyl 2-methoxyacetate as acyl donor
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The dynamic kinetic resolution (DKR) of various primary amine substrates was performed using a modified version of the Baeckvall system. A single equivalent of isopropyl 2-methoxyacetate was used as acyl donor in combination with p-MeO Shvo complex as the racemization catalyst and Novozym 435 as the acylation catalyst. A reaction temperature of 100°C was employed to ensure a high racemization rate. Adding 2,4-dimethyl-3-pentanol (DMP) as hydrogen donor at a concentration of 0.5 M successfully suppressed side product formation. Under these modified DKR conditions, complete conversion was observed for most substrates within 26 h showing both high ee values and good chemoselectivity, whereas the original system required a reaction time of 72 h. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Veld, Martijn A. J.,Hult, Karl,Palmans, Anja R. A.,Meijer
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p. 5416 - 5421
(2008/03/18)
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- Dynamic kinetic resolution of primary amines with a recyclable Pd nanocatalyst for racemization
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(Chemical Equation Presented) A practical procedure for the dynamic kinetic resolution (DKR) of primary amines has been developed. This procedure employs a palladium nanocatalyst as the racemization catalyst, a commercial lipase (Novozym-435) as the resol
- Kim, Mahn-Joo,Kim, Won-Hee,Han, Kiwon,Yoon, Kyung Choi,Park, Jaiwook
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p. 1157 - 1159
(2007/10/03)
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- Second Generation Sol-Gel Encapsulated Lipases: Robust Heterogeneous Biocatalysts
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The original procedure for the encapsulation of lipases in sol-gel materials produced by the fluoride-catalyzed hydrolysis of mixtures of RSi(OCH3)3 and Si(OCH3)4 has been improved considerably. This involves higher enzyme loading, variation of the alkylsilane precursor, and the use of additives such as isopropyl alcohol, 18-crown-6, Tween 80, methyl-β-cyclodextrin and/or KCl. A dramatic increase in enzyme activity is observed. The sol-gel lipase immobilizates are also excellent catalysts in the kinetic resolution of chiral alcohols and amines, recycling without any substantial loss in enantioselectivity and a residual activity of 70% being possible even after 20 reaction cycles.
- Reetz, Manfred T.,Tielmann, Patrick,Wiesenh?fer, Wolfgang,K?nen, Werner,Zonta, Albin
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p. 717 - 728
(2007/10/03)
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- Rapid determination of enantiomeric excess using infrared thermography
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Infrared thermography (IRT) is presented as a novel technique to screen a potentially large number of asymmetric catalysts or substrates in a high-throughput fashion. IRT was used as a simple, rapid, and practical approach for initial screening of the substrate specificity of Candida antarctica lipase. This was carried out using a 96-well microtitre plate format. Potential advantages and limitations of IRT for the enzymatic stereoselective acylation of primary and secondary alcohols of interest are discussed.
- Millot, Nicolas,Borman, Phil,Anson, Mike S.,Campbell, Ian B.,Macdonald, Simon J. F.,Mahmoudian, Mahmoud
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p. 463 - 470
(2013/09/06)
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