- Generation of Oxidoreductases with Dual Alcohol Dehydrogenase and Amine Dehydrogenase Activity
-
The l-lysine-?-dehydrogenase (LysEDH) from Geobacillus stearothermophilus naturally catalyzes the oxidative deamination of the ?-amino group of l-lysine. We previously engineered this enzyme to create amine dehydrogenase (AmDH) variants that possess a new hydrophobic cavity in their active site such that aromatic ketones can bind and be converted into α-chiral amines with excellent enantioselectivity. We also recently observed that LysEDH was capable of reducing aromatic aldehydes into primary alcohols. Herein, we harnessed the promiscuous alcohol dehydrogenase (ADH) activity of LysEDH to create new variants that exhibited enhanced catalytic activity for the reduction of substituted benzaldehydes and arylaliphatic aldehydes to primary alcohols. Notably, these novel engineered dehydrogenases also catalyzed the reductive amination of a variety of aldehydes and ketones with excellent enantioselectivity, thus exhibiting a dual AmDH/ADH activity. We envisioned that the catalytic bi-functionality of these enzymes could be applied for the direct conversion of alcohols into amines. As a proof-of-principle, we performed an unprecedented one-pot “hydrogen-borrowing” cascade to convert benzyl alcohol to benzylamine using a single enzyme. Conducting the same biocatalytic cascade in the presence of cofactor recycling enzymes (i.e., NADH-oxidase and formate dehydrogenase) increased the reaction yields. In summary, this work provides the first examples of enzymes showing “alcohol aminase” activity.
- Tseliou, Vasilis,Schilder, Don,Masman, Marcelo F.,Knaus, Tanja,Mutti, Francesco G.
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supporting information
p. 3315 - 3325
(2020/12/11)
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- Biochemical and Structural Characterization of an (R)-Selective Transaminase in the Asymmetric Synthesis of Chiral Hydroxy Amines
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An (R)-selective transaminase RbTA with excellent stereoselectivity (>99% ee) in the asymmetric amination of hydroxy ketones was identified. Biochemical characterization showed that RbTA exhibited the highest activity toward 4-hydroxy-2-butanone among reported enzymes, and that it has broad substrate specificity, including for aliphatic, aromatic, and alicyclic ketones. Crystallization of RbTA were performed, as were molecular docking and mutagenesis studies. Residue Tyr125 plays a key role in substrate recognition by forming a hydrogen bond with hydroxy ketone. The applicability of the enzyme was determined in preparative-scale synthesis of (R)-3-amino-1-butanol, demonstrating the potential of RbTA as a green biocatalyst for production of value-added chiral hydroxy amines. This study provides an efficient tool for enzymatic synthesis of chiral hydroxy amines, as well as structural insight into substrate recognition by transaminases in the asymmetric amination of hydroxy ketones. (Figure presented.).
- Li, Fulong,Liang, Youxiang,Wei, Yuwen,Zheng, Yukun,Du, Yan,Yu, Huimin
-
supporting information
p. 4582 - 4589
(2021/08/07)
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- The Synthesis of Primary Amines through Reductive Amination Employing an Iron Catalyst
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The reductive amination of ketones and aldehydes by ammonia is a highly attractive method for the synthesis of primary amines. The use of catalysts, especially reusable catalysts, based on earth-abundant metals is similarly appealing. Here, the iron-catalyzed synthesis of primary amines through reductive amination was realized. A broad scope and a very good tolerance of functional groups were observed. Ketones, including purely aliphatic ones, aryl–alkyl, dialkyl, and heterocyclic, as well as aldehydes could be converted smoothly into their corresponding primary amines. In addition, the amination of pharmaceuticals, bioactive compounds, and natural products was demonstrated. Many functional groups, such as hydroxy, methoxy, dioxol, sulfonyl, and boronate ester substituents, were tolerated. The catalyst is easy to handle, selective, and reusable and ammonia dissolved in water could be employed as the nitrogen source. The key is the use of a specific Fe complex for the catalyst synthesis and an N-doped SiC material as catalyst support.
- B?umler, Christoph,Bauer, Christof,Kempe, Rhett
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p. 3110 - 3114
(2020/06/01)
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- Ruthenium Catalyzed Direct Asymmetric Reductive Amination of Simple Aliphatic Ketones Using Ammonium Iodide and Hydrogen
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The direct conversion of ketones into chiral primary amines is a key transformation in chemistry. Here, we present a ruthenium catalyzed asymmetric reductive amination (ARA) of purely aliphatic ketones with good yields and moderate enantioselectivity: up to 99 percent yield and 74 percent ee. The strategy involves [Ru(PPh3)3H(CO)Cl] in combination with the ligand (S,S)-f-binaphane as the catalyst, NH4I as the amine source and H2 as the reductant. This is a straightforward and user-friendly process to access industrially relevant chiral aliphatic primary amines. Although the enantioselectivity with this approach is only moderate, to the extent of our knowledge, the maximum ee of 74 percent achieved with this system is the highest reported till now apart from enzyme catalysis for the direct transformation of ketones into chiral aliphatic primary amines.
- Ernst, Martin,Ghosh, Tamal,Hashmi, A. Stephen K.,Schaub, Thomas
-
supporting information
(2020/07/14)
-
- Separate Sets of Mutations Enhance Activity and Substrate Scope of Amine Dehydrogenase
-
Mutations were introduced into the leucine amine dehydrogenase (L-AmDH) derived from G. stearothermophilus leucine dehydrogenase (LeuDH) with the goals of increased activity and expanded substrate acceptance. A triple variant (L-AmDH-TV) including D32A, F101S, and C290V showed an average of 2.5-fold higher activity toward aliphatic ketones and an 8.0 °C increase in melting temperature. L-AmDH-TV did not show significant changes in relative activity for different substrates. In contrast, L39A, L39G, A112G, and T133G in varied combinations added to L-AmDH-TV changed the shape of the substrate binding pocket. L-AmDH-TV was not active on ketones larger than 2-hexanone. L39A and L39G enabled activity for straight-chain ketones as large as 2-decanone and in combination with A112G enabled activity toward longer branched ketones including 5-methyl-2-octanone.
- Franklin, Robert D.,Mount, Conner J.,Bommarius, Bettina R.,Bommarius, Andreas S.
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p. 2436 - 2439
(2020/04/16)
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- Development of an engineered thermostable amine dehydrogenase for the synthesis of structurally diverse chiral amines
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Amine dehydrogenases (AmDHs) are emerging as a class of attractive biocatalysts for synthesizing chiral amines via asymmetric reductive amination of ketones with inexpensive ammonia as an amino donor. However, the AmDHs developed to date exhibit limited substrate scope. Here, using directed evolution, we engineered a GkAmDH based on a thermostable phenylalanine dehydrogenase from Geobacillus kaustophilus. The newly developed AmDH is able to catalyze reductive amination of a diverse set of ketones and functionalized hydroxy ketones with ammonia or primary amines with up to >99% conversion, thus accessing structurally diverse chiral primary and secondary amines and chiral vicinal amino alcohols, with excellent enantioselectivity (up to >99% ee) and releasing water as the sole by-product.
- Chen, Fei-Fei,Chen, Qi,Liu, Lei,Wang, Dong-Hao,Wang, Zhi-Long,Xu, Jian-He,Zhang, Zhi-Jun,Zheng, Gao-Wei
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p. 2353 - 2358
(2020/05/13)
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- Multi-enzyme pyruvate removal system to enhance (: R)-selective reductive amination of ketones
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Biocatalytic transamination is widely used in industrial production of chiral chemicals. Here, we constructed a novel multi-enzyme system to promote the conversion of the amination reaction. Firstly, we constructed the ArR-ωTA/TdcE/FDH/LDH multi-enzyme system, by combination of (R)-selective ω-transaminase derived from Arthrobacter sp. (ArR-ωTA), formate dehydrogenase (FDH) derived from Candida boidinii, formate acetyltransferase (TdcE) and lactate dehydrogenase (LDH) derived from E. coli MG1655. This multi-enzyme system was used to efficiently remove the by-product pyruvate by TdcE and LDH to facilitate the transamination reaction. The TdcE/FDH pathway was found to dominate the by-product pyruvate removal in the transamination reaction. Secondly, we optimized the reaction conditions, including d-alanine, DMSO, and pyridoxal phosphate (PLP) with different concentration of 2-pentanone (as a model substrate). Thirdly, by using the ArR-ωTA/TdcE/FDH/LDH system, the conversions of 2-pentanone, 4-phenyl-2-butanone and cyclohexanone were 84.5%, 98.2% and 79.3%, respectively.
- Li, Chao,Song, Hao,Zhang, Jinhua,Zhao, Yanshu
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p. 28984 - 28991
(2020/08/25)
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- Amination of aliphatic alcohols with urea catalyzed by ruthenium complexes: effect of supporting ligands
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In the present study, ruthenium-catalyzed amination of alcohols by urea as a convenient ammonia carrier in the presence of free diphosphine ligands has been described. A number of ruthenium-phosphine complexes have been studied among which, [(Cp)RuCl(dppe)] was found as an efficient catalyst for alcohol amination reaction. The crystal structures of two new half-sandwich ruthenium complexes, [(Cp)RuCl(dppe)] and [(C6H6)RuCl2(PHEt2)], were determined by X-ray crystallographic analysis. Also the effect of using different supporting phosphines, ratio of raw materials and reaction temperature on conversion and selectivity was investigated. Under optimum reaction conditions high conversion (98percent) and chemo-selectivity toward secondary amines were obtained.
- Dindar, Sara,Nemati Kharat, Ali
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- Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
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Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
- An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
-
supporting information
p. 6216 - 6226
(2020/04/27)
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- An Ammonium-Formate-Driven Trienzymatic Cascade for ω-Transaminase-Catalyzed (R)-Selective Amination
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(R)-Amination mediated by (R)-specific ω-transaminases generally requires costly d-alanine in excess to obtain the desired chiral amines in high yield. Herein, a one-pot, trienzymatic cascade comprising an (R)-specific ω-transaminase, an amine dehydrogenase, and a formate dehydrogenase was developed for the economical and eco-friendly synthesis of (R)-chiral amines. Using inexpensive ammonium formate as the sole sacrificial agent, the established cascade system enabled efficient ω-transaminase-mediated (R)-amination of various ketones, with high conversions and excellent ee (>99%); water and CO2 were the only waste products.
- Chen, Fei-Fei,Liu, Lei,Wu, Jian-Ping,Xu, Jian-He,Zhang, Yu-Hui,Zhang, Zhi-Jun,Zheng, Gao-Wei
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p. 14987 - 14993
(2019/12/02)
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- Generation of amine dehydrogenases with increased catalytic performance and substrate scope from ε-deaminating L-Lysine dehydrogenase
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Amine dehydrogenases (AmDHs) catalyse the conversion of ketones into enantiomerically pure amines at the sole expense of ammonia and hydride source. Guided by structural information from computational models, we create AmDHs that can convert pharmaceutically relevant aromatic ketones with conversions up to quantitative and perfect chemical and optical purities. These AmDHs are created from an unconventional enzyme scaffold that apparently does not operate any asymmetric transformation in its natural reaction. Additionally, the best variant (LE-AmDH-v1) displays a unique substrate-dependent switch of enantioselectivity, affording S- or R-configured amine products with up to >99.9% enantiomeric excess. These findings are explained by in silico studies. LE-AmDH-v1 is highly thermostable (Tm of 69 °C), retains almost entirely its catalytic activity upon incubation up to 50 °C for several days, and operates preferentially at 50 °C and pH 9.0. This study also demonstrates that product inhibition can be a critical factor in AmDH-catalysed reductive amination.
- Tseliou, Vasilis,Knaus, Tanja,Masman, Marcelo F.,Corrado, Maria L.,Mutti, Francesco G.
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- Deracemization of Racemic Amines to Enantiopure (R)- and (S)-amines by Biocatalytic Cascade Employing ω-Transaminase and Amine Dehydrogenase
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A one-pot deracemization strategy for α-chiral amines is reported involving an enantioselective deamination to the corresponding ketone followed by a stereoselective amination by enantiocomplementary biocatalysts. Notably, this cascade employing a ω-transaminase and amine dehydrogenase enabled the access to both (R)-and (S)-amine products, just by controlling the directions of the reactions catalyzed by them. A wide range of (R)-and (S)-amines was obtained with excellent conversions (>80 %) and enantiomeric excess (>99 % ee). Finally, preparative scale syntheses led to obtain enantiopure (R)- and (S)-13 with the isolated yields of 53 and 75 %, respectively.
- Yoon, Sanghan,Patil, Mahesh D.,Sarak, Sharad,Jeon, Hyunwoo,Kim, Geon-Hee,Khobragade, Taresh P.,Sung, Sihyong,Yun, Hyungdon
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p. 1898 - 1902
(2019/02/27)
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- Efficient synthesis of enantiopure amines from alcohols using resting: E. coli cells and ammonia
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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.
- Houwman, Joseline A.,Knaus, Tanja,Costa, Magda,Mutti, Francesco G.
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supporting information
p. 3846 - 3857
(2019/07/31)
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- Upgraded Bioelectrocatalytic N2 Fixation: From N2 to Chiral Amine Intermediates
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Enantiomerically pure chiral amines are of increasing value in the preparation of bioactive compounds, pharmaceuticals, and agrochemicals. ω-Transaminase (ω-TA) is an ideal catalyst for asymmetric amination because of its excellent enantioselectivity and wide substrate scope. To shift the equilibrium of reactions catalyzed by ω-TA to the side of the amine product, an upgraded N2 fixation system based on bioelectrocatalysis was developed to realize the conversion from N2 to chiral amine intermediates. The produced NH3 was in situ reacted with l-alanine dehydrogenase to generate alanine with NADH as a coenzyme. ω-TA transferred the amino group from alanine to ketone substrates and finally produced the desired chiral amine intermediates. The cathode of the upgraded N2 fixation system supplied enough reducing power to synchronously realize the regeneration of reduced methyl viologen (MV?+) and NADH for the nitrogenase and l-alanine dehydrogenase. The coproduct, pyruvate, was consumed by l-alanine dehydrogenase to regenerate alanine and push the equilibrium to the side of amine. After 10 h of reaction, the concentration of 1-methyl-3-phenylpropylamine achieved 0.54 mM with the 27.6% highest faradaic efficiency and >99% enantiomeric excess (eep). Because of the wide substrate scope and excellent enantioselectivity of ω-TA, the upgraded N2 fixation system has great potential to produce a variety of chiral amine intermediates for pharmaceuticals and other applications.
- Chen, Hui,Cai, Rong,Patel, Janki,Dong, Fangyuan,Chen, Hsiaonung,Minteer, Shelley D.
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p. 4963 - 4971
(2019/03/26)
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- Rapid and Quantitative Profiling of Substrate Specificity of ω-Transaminases for Ketones
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ω-Transaminases (ω-TAs) have gained growing attention owing to their capability for asymmetric synthesis of chiral amines from ketones. Reliable high-throughput activity assay of ω-TAs is essential in carrying out extensive substrate profiling and establishing a robust screening platform. Here we report spectrophotometric and colorimetric methods enabling rapid quantitation of ω-TA activities toward ketones in a 96-well microplate format. The assay methods employ benzylamine, a reactive amino donor for ω-TAs, as a cosubstrate and exploit aldehyde dehydrogenase (ALDH) as a reporter enzyme, leading to formation of benzaldehyde detectable by ALDH owing to concomitant NADH generation. Spectrophotometric substrate profiling of two wild-type ω-TAs of opposite stereoselectivity was carried out at 340 nm with 22 ketones, revealing subtle differences in substrate specificities that were consistent with docking simulation results obtained with cognate amines. Colorimetric readout for naked eye detection of the ω-TA activity was also demonstrated by supplementing the assay mixture with color-developing reagents whose color reaction could be quantified at 580 nm. The colorimetric assay was applied to substrate profiling of an engineered ω-TA for 24 ketones, leading to rapid identification of reactive ketones. The ALDH-based assay is expected to be promising for high-throughput screening of enzyme collections and mutant libraries to fish out the best ω-TA candidate as well as to tailor enzyme properties for efficient amination of a target ketone.
- Han, Sang-Woo,Shin, Jong-Shik
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p. 3287 - 3295
(2019/06/21)
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- Reshaping the Active Pocket of Amine Dehydrogenases for Asymmetric Synthesis of Bulky Aliphatic Amines
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The asymmetric reductive amination of ketones with ammonia using engineered amine dehydrogenases (AmDHs) is a particularly attractive and environmentally friendly method for the synthesis of chiral amines. However, one major challenge for these engineered AmDHs is their limited range of accepted substrates. Herein, several engineered AmDHs were developed through the evolution of naturally occurring leucine dehydrogenases, which displayed good amination activity toward aliphatic ketones but restricted catalytic scope for short-chain substrates. Computational analysis helped identify two residues, located at the distal end of the substrate-binding cavity, that generate steric hindrance and prevent the binding of bulky aliphatic ketones. By fine-tuning these two key hotspots, the resulting AmDH mutants are able to accept previously inaccessible bulky substrates. More importantly, the mutations were also proved applicable for expanding the substrate scope of other homologous AmDHs with sequence identities as low as 70%, indicating a broad effect on the development of AmDHs and the synthesis of structurally diverse chiral amines.
- Chen, Fei-Fei,Zheng, Gao-Wei,Liu, Lei,Li, Hao,Chen, Qi,Li, Fu-Long,Li, Chun-Xiu,Xu, Jian-He
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p. 2622 - 2628
(2018/03/13)
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- Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones
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Transformation of biomass into valuable nitrogen-containing compounds is highly desired, yet limited success has been achieved. Here we report an efficient catalyst system, partially reduced Ru/ZrO2, which could catalyze the reductive amination of a variety of biomass-derived aldehydes/ketones in aqueous ammonia. With this approach, a spectrum of renewable primary amines was produced in good to excellent yields. Moreover, we have demonstrated a two-step approach for production of ethanolamine, a large-market nitrogen-containing chemical, from lignocellulose in an overall yield of 10 %. Extensive characterizations showed that Ru/ZrO2-containing multivalence Ru association species worked as a bifunctional catalyst, with RuO2 as acidic promoter to facilitate the activation of carbonyl groups and Ru as active sites for the subsequent imine hydrogenation.
- Liang, Guanfeng,Wang, Aiqin,Li, Lin,Xu, Gang,Yan, Ning,Zhang, Tao
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supporting information
p. 3050 - 3054
(2017/03/14)
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- Two-Enzyme Hydrogen-Borrowing Amination of Alcohols Enabled by a Cofactor-Switched Alcohol Dehydrogenase
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The NADPH-dependent secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus (TeSADH), displaying broad substrate specificity and low enantioselectivity, was engineered to accept NADH as a cofactor. The engineered TeSADH showed a >10 000-fold switch from NADPH towards NADH compared to the wildtype enzyme. This TeSADH variant was applied to a biocatalytic hydrogen-borrowing system that employed catalytic amounts of NAD+, ammonia, and an amine dehydrogenase, which thereby enabled the conversion a range of alcohols into chiral amines.
- Thompson, Matthew P.,Turner, Nicholas J.
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p. 3833 - 3836
(2017/09/25)
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- In vitro biocatalytic pathway design: Orthogonal network for the quantitative and stereospecific amination of alcohols
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The direct and efficient conversion of alcohols into amines is a pivotal transformation in chemistry. Here, we present an artificial, oxidation-reduction, biocatalytic network that employs five enzymes (alcohol dehydrogenase, NADP-oxidase, catalase, amine dehydrogenase and formate dehydrogenase) in two concurrent and orthogonal cycles. The NADP-dependent oxidative cycle converts a diverse range of aromatic and aliphatic alcohol substrates to the carbonyl compound intermediates, whereas the NAD-dependent reductive aminating cycle generates the related amine products with >99% enantiomeric excess (R) and up to >99% conversion. The elevated conversions stem from the favorable thermodynamic equilibrium (K′eq = 1.88 × 1042 and 1.48 × 1041 for the amination of primary and secondary alcohols, respectively). This biocatalytic network possesses elevated atom efficiency, since the reaction buffer (ammonium formate) is both the aminating agent and the source of reducing equivalents. Additionally, only dioxygen is needed, whereas water and carbonate are the by-products. For the oxidative step, we have employed three variants of the NADP-dependent alcohol dehydrogenase from Thermoanaerobacter ethanolicus and we have elucidated the origin of the stereoselective properties of these variants with the aid of in silico computational models.
- Knaus, Tanja,Cariati, Luca,Masman, Marcelo F,Mutti, Francesco G.
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p. 8313 - 8325
(2017/10/19)
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- Asymmetric catalysis of the carbonyl-amine condensation: Kinetic resolution of primary amines
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A Br?nsted acid catalyzed kinetic resolution of primary amines is described that is based on the condensation between an amine and a carbonyl compound. 1,3-Diketones react with racemic α-branched amines to furnish the corresponding enantioenriched enaminone and recovered starting material. Good to excellent enantioselectivity was observed with both aromatic and aliphatic primary amines. This process represents the first small-molecule catalyzed kinetic resolution of aliphatic amines.
- Das, Sayantani,Majumdar, Nilanjana,De, Chandra Kanta,Kundu, Dipti Sankar,Dohring, Arno,Garczynski, Anika,List, Benjamin
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supporting information
p. 1357 - 1359
(2017/02/10)
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- Amine dehydrogenases: Efficient biocatalysts for the reductive amination of carbonyl compounds
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Amines constitute the major targets for the production of a plethora of chemical compounds that have applications in the pharmaceutical, agrochemical and bulk chemical industries. However, the asymmetric synthesis of α-chiral amines with elevated catalytic efficiency and atom economy is still a very challenging synthetic problem. Here, we investigated the biocatalytic reductive amination of carbonyl compounds employing a rising class of enzymes for amine synthesis: amine dehydrogenases (AmDHs). The three AmDHs from this study-operating in tandem with a formate dehydrogenase from Candida boidinii (Cb-FDH) for the recycling of the nicotinamide coenzyme-performed the efficient amination of a range of diverse aromatic and aliphatic ketones and aldehydes with up to quantitative conversion and elevated turnover numbers (TONs). Moreover, the reductive amination of prochiral ketones proceeded with perfect stereoselectivity, always affording the (R)-configured amines with more than 99% enantiomeric excess. The most suitable amine dehydrogenase, the optimised catalyst loading and the required reaction time were determined for each substrate. The biocatalytic reductive amination with this dual-enzyme system (AmDH-Cb-FDH) possesses elevated atom efficiency as it utilizes the ammonium formate buffer as the source of both nitrogen and reducing equivalents. Inorganic carbonate is the sole by-product.
- Knaus, Tanja,B?hmer, Wesley,Mutti, Francesco G.
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p. 453 - 463
(2017/08/14)
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- Asymmetric Amination of Secondary Alcohols by using a Redox-Neutral Two-Enzyme Cascade
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Multienzyme cascade approaches for the synthesis of optically pure molecules from simple achiral compounds are desired. Herein, a cofactor self-sufficient cascade protocol for the asymmetric amination of racemic secondary alcohols to the corresponding chiral amines was successfully constructed by employing an alcohol dehydrogenase and a newly developed amine dehydrogenase. The compatibility and the identical cofactor dependence of the two enzymes led to an ingenious in situ cofactor recycling system in the one-pot synthesis. The artificial redox-neutral cascade process allowed the transformation of racemic secondary alcohols into enantiopure amines with considerable conversions (up to 94 %) and >99 % enantiomeric excess at the expense of only ammonia; this method thus represents a concise and efficient route for the asymmetric synthesis of chiral amines. If you know what amine: A redox-neutral two-enzyme cascade encompassing an alcohol dehydrogenase (ADH) and an amine dehydrogenase (AmDH) is constructed for the synthesis of chiral amines from the corresponding racemic alcohols in one pot to afford considerable conversions (up to 94 %) and high enantiomeric excess values (>99 %) at the expense of only ammonia.
- Chen, Fei-Fei,Liu, You-Yan,Zheng, Gao-Wei,Xu, Jian-He
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p. 3838 - 3841
(2016/01/26)
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- Conversion of alcohols to enantiopure amines through dual-enzyme hydrogen-borrowing cascades
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α-Chiral amines are key intermediates for the synthesis of a plethora of chemical compounds at industrial scale. We present a biocatalytic hydrogen-borrowing amination of primary and secondary alcohols that allows for the efficient and environmentally benign production of enantiopure amines. The method relies on a combination of two enzymes: an alcohol dehydrogenase (from Aromatoleum sp., Lactobacillus sp., or Bacillus sp.) operating in tandem with an amine dehydrogenase (engineered from Bacillus sp.) to aminate a structurally diverse range of aromatic and aliphatic alcohols, yielding up to 96% conversion and 99% enantiomeric excess. Primary alcohols were aminated with high conversion (up to 99%). This redox self-sufficient cascade possesses high atom efficiency, sourcing nitrogen from ammonium and generating water as the sole by-product.
- Mutti, Francesco G.,Knaus, Tanja,Scrutton, Nigel S.,Breuer, Michael,Turner, Nicholas J.
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p. 1525 - 1529
(2015/10/05)
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- ω-Transaminase-catalyzed kinetic resolution of chiral amines using l-threonine as an amino acceptor precursor
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Kinetic resolution of chiral amines using l-threonine as a cosubstrate was demonstrated by a biocatalytic strategy in which (S)-selective ω-transaminase (ω-TA) was coupled with threonine deaminase (TD), eliminating the need to use an expensive keto acid as an amino acceptor. The coupled enzyme reaction enabled simultaneous production of enantiopure (R)-amine and l-homoalanine which are pharmaceutically important building blocks. To extend the versatility of this strategy to production of both enantiomers of chiral amines, (R)-selective ω-TA coupled with TD was employed to produce (S)-amine.
- Malik, M. Shaheer,Park, Eul-Soo,Shin, Jong-Shik
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supporting information; experimental part
p. 2137 - 2140
(2012/09/25)
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- Enantiopure cyclic O-substituted phenylphosphonothioic acid: Synthesis and chirality-recognition ability
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As a new acidic selector (resolving agent), we synthesized an enantiopure O-alkyl phenylphosphonothioic acid with a seven-membered ring ((R)-5), which was designed on the basis of the results for the enantioseparation of 1-arylethylamine derivatives with acyclic O-ethyl phenylphosphonothioic acid (I). The phosphonothioic acid (R)-5 showed unique chirality-recognition ability in the enantioseparation of 1-naphthylethylamine derivatives, aliphatic secondary amines, and amino alcohols; the ability was complementary to that of I. The X-ray crystallographic analyses of the less- and more-soluble diastereomeric salts showed that hydrogen-bonding networks in the salt crystals are 21-column-type with a single exception which is cluster-type. In the cases of the 21-column-type crystals, stability of the crystals is firstly governed by hydrogen bonds to form a 21-column and secondly determined by intra-columnar T-shaped CH/π interaction(s), intra-columnar hydrogen bond(s), inter-columnar van der Waals interaction and/or inter-columnar T-shaped CH/π interaction(s). In contrast, the cluster-type salt crystal is stabilized by the assistance of inter-cluster T-shaped CH/π and van der Waals interactions. To realize still more numbers of intra- and inter-columnar and -cluster T-shaped CH/π interactions, the seven-membered ring of (R)-5 plays a considerable role. Copyright
- Ribeiro, Nigel,Kobayashi, Yuka,Maeda, Jin,Saigo, Kazuhiko
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experimental part
p. 438 - 448
(2012/01/02)
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- Enzymatic asymmetric synthesis of enantiomerically pure aliphatic, aromatic and arylaliphatic amines with (R)-selective amine transaminases
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Seven (R)-selective amine transaminases (R-ATAs) recently discovered by an in silico-based approach in sequence databases were produced recombinantly in Escherichia coli and subjected to partial purification by ammonium sulfate precipitation. A range of additives and various buffers were investigated to identify best conditions to ensure good storage stability and stable activity during biocatalysis. All enzymes show pH optima between pH 7.5-9. These R-ATAs were then applied in the asymmetric synthesis of twelve aliphatic, aromatic and arylaliphatic (R)-amines starting from the corresponding prochiral ketones using a lactate dehydrogenase/glucose dehydrogenase system to shift the equilibrium. For all ketones, at least one enzyme was found that allows complete conversion to the corresponding chiral amine having excellent optical purities >99% ee. Variations in substrate profiles are also discussed based on the phylogenetic relationships between the seven R-ATAs. Thus, we have identified a versatile toolbox of (R)-amine transaminases showing remarkable properties for application in biocatalysis. Copyright
- Schaetzle, Sebastian,Steffen-Munsberg, Fabian,Thontowi, Ahmad,Hoehne, Matthias,Robins, Karen,Bornscheuer, Uwe T.
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experimental part
p. 2439 - 2445
(2011/11/06)
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- Stereoselectivity of four (R)-selective transaminases for the asymmetric amination of ketones
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Four (R)-ω-transaminases originating from Hyphomonas neptunium (HN-ωTA), Aspergillus terreus (AT-ωTA) and Arthrobacter sp. (ArR-ωTA), as well as an evolved transaminase (ArRmut11-ωTA) were successfully employed for the amination of prochiral ketones leading to optically pure (R)-amines. The first three transaminases displayed perfect stereoselectivity for the amination of all substrates tested (ee >99%). Furthermore, the transaminase AT-ωTA led in most cases to better conversion than ArR-ωTA and HN-ωTA using D-alanine as amine donor. α-Tetralone, which was the only substrate not accepted by HN-ωTA, ArR-ωTA, and AT-ωTA, was successfully transformed with perfect enantioselectivity (ee >99%) into the corresponding optically pure amine employing the variant ArRmut11-ωTA. Copyright
- Mutti, Francesco G.,Fuchs, Christine S.,Pressnitz, Desiree,Sattler, Johann H.,Kroutil, Wolfgang
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experimental part
p. 3227 - 3233
(2012/01/03)
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- Asymmetric intermolecular hydroamination of unactivated alkenes with simple amines
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A hard nut to crack: The asymmetric intermolecular Markovnikov addition of simple amines to unactivated alkenes can be achieved utilizing binaphtholate rare-earth-metal catalysts with up to 61% ee and 73% de in the case where R 2 contains a stereogenic center.
- Reznichenko, Alexander L.,Nguyen, Hiep N.,Hultzsch, Kai C.
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supporting information; experimental part
p. 8984 - 8987
(2011/02/21)
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- Efficient enzymatic kinetic resolution of 2-heptylamine with a highly active acyl donor
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Novozyme435 facilitated kinetic resolution of 2-heptylamine was here presented. Methyl methoxyacetate was used as acyl donor. A survey of influencing factors including hydrogen bonding effect, solvent effect, steric effect, temperature and the amount of acyl donor were investigated in detail. At the optimum conditions, the enantiomeric separation was successfully obtained within 8 h at 20 °C, and gave high conversion and optical purity of (R)-2-heptylamine, 48.9% and over 99% respectively. The immobilized lipase B was found to be suitable for the enantiomeric separation of aliphatic amines with good recyclability.
- Sun, Jian-Hua,Dai, Rong-Ji,Meng, Wei-Wei,Deng, Yu-Lin
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experimental part
p. 987 - 991
(2010/11/16)
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- Deracemisation of α-chiral primary amines by a one-pot, two-step cascade reaction catalysed by ω-transaminases
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Racemic a-chiral primary amines were deracemised to optically pure amines in up to >99 % conversion and >99 % ee within 48 h. The deracemisation was a result of a stereoinver- sion of one amine enantiomer; the formal stereoinversion was achieved by a one-pot, two-step procedure: in the first step, kinetic resolution of the chiral racemic amine was performed by employing a -transaminase to yield an intermediate ketone and the remaining optically pure amine; in the second step, the ketone intermediate was stereoselectively transformed into the amine by employing alanine as the amine donor and a -transaminase displaying opposite stereopref- erence than the -transaminase in the first step. In the second step, lactate dehydrogenase was used to remove the side product pyruvate to shift the unfavourable reaction equilibrium to the product side. Depending on the order of the en- antiocomplementary enzymes employed in the cascade, the (R), as well as the (S), enantiomer was accessible.
- Koszelewski, Dominik,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
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experimental part
p. 2289 - 2292
(2009/08/09)
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- Formal asymmetric biocatalytic reductive amination
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All for one: A combination of three biocatalysts (ω-transaminase, alanine dehydrogenase, and an enzyme such as formate dehydrogenase for cofactor recycling) catalyze a cascade to achieve the asymmetric transformation of a ketone into a primary α-chiral unprotected amine through a formal stereoselective reductive amination (see scheme). Only ammonia and the reducing agent (formate) are consumed during this reaction. (Chemical Equation Presented).
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Guebitz, Georg M.,Rozzell, David,Kroutil, Wolfgang
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supporting information; experimental part
p. 9337 - 9340
(2009/05/15)
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- Asymmetric synthesis of optically pure pharmacologically relevant amines employing ω-transaminases
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Various ω-transaminases were tested for the synthesis of enantiomerically pure amines from the corresponding ketones employing D- or L-alanine as amino donor and lactate dehydrogenase to remove the side-product pyruvate to shift the unfavourable reaction equilibrium to the product side. Both enantiomers, (R)- and (S)-amines, could be prepared with up to 99% ee and >99% conversions within 24 h at 50 mM substrate concentration. The activity and stereoselectivity of the amination reaction depended on the ω-transaminase and substrate employed; furthermore the co-solvent significantly influenced both the stereoselectivity and activity of the transaminases. Best results were obtained by employing ATA-117 to obtain the (R)-enantiomer and ATA-113 or ATA-103 to access the (S)-enantiomer with 15% v v-1 DMSO.
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
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scheme or table
p. 2761 - 2766
(2009/10/06)
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- The dutch resolution variant of the classical resolution of racemates by formation of diastereomeric salts: Family behaviour in nucleation inhibition
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The resolution of racemates through their diastereomeric salts can be positively affected by the addition of small amounts of suitable nucleation inhibitors. This discovery is a logical extension of "Dutch Resolution", in which equimolar amounts of resolving agents that are members of the same family (i.e., structurally related) are used. We conducted a systematic search for nucleation inhibitors of the resolving agent 1-phenylethylamine. A wide range of amines that bear possible family resemblances to 1-phenylethylamine was investigated. It was found that (R)-1-phenylbutylamine is a good inhibitor of (R)-1-phenylethylamine. Results of turbidity measurements showed that, for the model case of mandelic acid resolution, the chief effect of this inhibitor was to widen the metastable zone for the more soluble diastereomer. This observation is in accordance with previous experience. Further scouting for possible family members revealed a wide variation in the effectiveness of inhibitors, dependent on their structure. By far the most effective inhibitors are bifunctional 1-phenylethylamine and/or 1-phenylbutylamine analogues. The effect of racemic inhibitors was found to approach that of enantiomerically pure inhibitors of the same absolute configuration of the 1-phenylethylamine used for resolution. The most effective inhibitors were tested for the resolution of a structural variety of racemates, and were shown to be broadly applicable.
- Dalmolen, Jan,Tiemersma-Wegman, Theodora D.,Nieuwenhuijzen, Jose W.,Van Der Sluis, Marcel,Van Echten, Erik,Vries, Ton R.,Kaptein, Bernard,Broxterman, Quirinius B.,Kellogg, Richard M.
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p. 5619 - 5624
(2007/10/03)
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- Enantioselective synthesis of α,α-disubstituted amines from nitroalkenes
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Disubstituted nitroalkenes were converted into enantiomerically enriched amines (isolated as their hydrochloride salts) with enantiometric excesses of 88 to >95% in there steps: (a) highly stereoselective conjugate addition of the potassium salt of 4-phenyloxazolidin-2-one; (b) radical-mediated removal of the nitro group; (c) cleavage of the oxazolidinone.
- Leroux, Mary-Lorene,Le Gall, Thierry,Mioskowski, Charles
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p. 1817 - 1823
(2007/10/03)
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- Development of chiral N-alkylcarbamates as new leads for potent and selective H3-receptor antagonists: Synthesis, capillary electrophoresis, and in vitro and oral in vivo activity
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Novel carbamates as derivatives of 3-(1H-imidazol-4-yl)propanol with an N-alkyl chain were prepared as histamine H3-receptor antagonists. Branching of the N-alkyl side chain with methyl groups led to chiral compounds which were synthesized stereospecifically by a Mitsunobu protocol adapted Gabriel synthesis. The optical purity of some of the chiral compounds was determined (ee > 95%) by capillary electrophoresis (CE). The investigated compounds showed pronounced to high antagonist activity (K(i) values of 4.1-316 nM) in a functional test for histamine H3 receptors on rat cerebral cortex synaptosomes. Similar H3-receptor antagonist activities were observed in a peripheral model on guinea pig ileum. No stereoselective discrimination for the H3 receptor for the chiral antagonists was found with the in vitro assays. All compounds were also screened for central H3-receptor antagonist activity in vivo in mice after po administration. Most compounds were potent agents of the H3-receptor-mediated enhancement of brain N(τ)- methylhistamine levels. The enantiomers of the N-2-heptylcarbamate showed a stereoselective differentiation in their pharmacological effect in vivo (ED50 of 0.39 mg/kg for the (S)-derivative vs 1.5 mg/kg for the (R)- derivative) most probably caused by differences in pharmacokinetic parameters. H1- and H2-receptor activities were determined for some of the novel carbamates, demonstrating that they have a highly selective action at the histamine H3 receptor.
- Sasse, Astrid,Kiec-Kononowicz, Katarzyna,Stark, Holger,Motyl, Malgorzata,Reidemeister, Sibylle,Ganellin, C. Robin,Ligneau, Xavier,Schwartz, Jean-Charles,Schunack, Walter
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p. 593 - 600
(2007/10/03)
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- Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
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Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
- Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
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- Preparation process of aminoacetamide derivative
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Disclosed herein are novel processes for preparing aminoacetamide derivatives, wherein: (1) a secondary amine is reacted with a 2-haloacetamide in the presence or absence of at least one solvent selected from water, lower alcohols, aromatic solvents and acetic acid esters; (2) an N-benzylideneamine derivative is reacted with dimethyl sulfate or diethyl sulfate to form a secondary amine, and this secondary amine is then reacted with a 2-haloacetamide; and (3) a primary amine is reacted with benzaldehyde to form an N-benzylideneamine derivative, this product is then reacted with dimethyl sulfate or diethyl sulfate to form a secondary amine, and this secondary amine is further reacted with a 2-haloacetamide. The 2-aminoacetamide derivatives are useful as intermediates for the preparation of novel antibiotics.
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- Optimized procedures for one-pot conversion of alkyl bromides into amines via the Staudinger reaction
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New optimized procedures for transforming primary and secondary alkyl bromides into the corresponding primary amine salts have been elaborated. Essential modifications of azidation and deprotection of intermediate triethoxyphosphine alkylimides resulted in substantial improvement of the overall yields. Conversion of ammonium tosylates and hydrochlorides into free amines in a nonaqueous medium is described.
- Koziara,Zwierzak
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p. 1063 - 1065
(2007/10/02)
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- Quaternary alkynoxymethyl amines
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This invention relates to quaternaries of alkynoxymethyl amines and uses thereof. These may be summarized by the following formulae: STR1 where R and R' are substituted groups such as alkyl, aryl, etc.; R'" is an acetylenic group; and X is an anion; and STR2 where R and R'" having the same meaning as in (1) and Z is a bridging group, preferably hydrocarbon such as alkylene, alkinylene, alkenylene, arylene, etc.
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- Microbiocidal quaternaries of halogen derivatives of alkynoxymethyl amines
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This invention relates to quaternaries of halogen derivatives of alkynoxymethyl amines and uses thereof. These may be summarized by the following formulae: STR1 where R and R' are substituted groups such as alkyl, aryl, etc.; R" is an alkylidene group; and X is halogen and A is an anion; and STR2 where R, R' and R" having the same meaning as in (1) and Z is a bridging group, preferably hydrocarbon such as alkylene, alkinylene, alkenylene, arylene, etc.
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- 1,4-Dithiino[2,3-c; 6,5-c']diisothiazole and related compounds
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The compound 3,7-dicyano-1,4-dithiino[2,3-c; 6,5-c']diisothiazole is prepared by reacting either tetracyano-1,4-dithiin or 4,5-dicyano-1,3-dithiolen-2-one with sulfur in 1,2-dimethoxyethane at a temperature of 50°-280° C in the presence of a basic catalyst. The diisothiazole can be converted to derivatives with various utilities, e.g., as fluorescent brighteners.
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- Halogen derivatives of alkynoxymethyl amines
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This invention relates to halogen derivatives of alkynoxymethylamines and to uses thereof. The present invention may be ideally illustrated by the following equation: where R is a substituted group, preferably hydrocarbon, such as alkyl, cycloalkyl, aryl, etc., R' is hydrocarbon, preferably alkylene, and where X is halogen.
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- Alkynoxymethyl amines
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This invention relates to alkynoxymethyl amines, to methods of preparing them, and uses thereof, particularly as corrosion inhibitors. These compounds are prepared by reacting an amine, such as RNH2, with an aldehyde, such as formaldehyde, and an alkynol, such as propargyl alcohol, to yield compounds of the formula where R is a substituted group, preferably alkyl, cycloalkyl, aryl, etc., and R' is an acetylenic alcohol moiety.
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