- 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
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p. 4582 - 4589
(2021/08/07)
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- Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
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Efficient synthesis of primary amines via low-temperature reductive amination of carbonyl compounds using NH3 and H2 as the nitrogen and hydrogen resources is highly desired and challenging in the chemistry community. Herein, we employed naturally occurring phytic acid as a renewable precursor to fabricate titanium phosphate (TiP)-supported Ru nanocatalysts with different reduction degrees of RuO2 (Ru/TiP-x, x represents the reduction temperature) by combining ball milling and molten-salt processes. Very interestingly, the obtained Ru/TiP-100 had good catalytic performance for the reductive amination of carbonyl compounds at ambient temperature, resulting from the synergistic cooperation of the support (TiP) and the Ru/RuO2 with a suitable proportion of Ru0 (52%). Various carbonyl compounds could be efficiently converted into the corresponding primary amines with high yields. More importantly, the conversion of other substrates with reducible groups could also be achieved at ambient temperature. Detailed investigations indicated that the partially reduced Ru and the support (TiP) were indispensable. The high activity and selectivity of Ru/TiP-100 catalyst originates from the relatively high acidity and the suitable electron density of metallic Ru0.
- Xie, Chao,Song, Jinliang,Hua, Manli,Hu, Yue,Huang, Xin,Wu, Haoran,Yang, Guanying,Han, Buxing
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p. 7763 - 7772
(2020/08/21)
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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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- Rapid synthesis method of biomass-based amide
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The invention discloses a rapid synthesis method of biomass-based amide, which comprises the steps: formamide is used as an amine source, formic acid is used as a hydrogen source, biomass aldehyde andketone is used as a raw material, the direct addition of formamide and aldehyde and ketone components and the reduction of formic acid is promoted to prepare the corresponding formamide derivative byrapidly heating under microwave-assisted heating and in the absence of a solvent and a catalyst; the formamide derivative is selectively converted to the corresponding primary amide by alcoholysis under the action of a base. The microwave assisted heating reaction system of the invention has higher catalytic efficiency than the corresponding oil bath system, greatly shortens the reaction time, remarkably improves the selectivity. The conversion rate of the biomass aldehyde or ketone compound is at least 99%, and the yield of the formamide derivative can reach 85 to 99%; the formamide can be synthesized by alcoholysis to obtain a primary amide with a yield of 92 to 99%.
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Paragraph 0058; 0061-0063
(2019/01/15)
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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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- En Route to a Practical Primary Alcohol Deoxygenation
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A long-standing scientific challenge in the field of alcohol deoxygenation has been direct catalytic sp3 C-O defunctionalization with high selectivity and efficiency, in the presence of other functionalities, such as free hydroxyl groups and amines widely present in biological molecules. Previously, the selectivity issue had been only addressed by classic multistep deoxygenation strategies with stoichiometric reagents. Herein, we propose a catalytic late-transition-metal-catalyzed redox design, on the basis of dehydrogenation/Wolff-Kishner (WK) reduction, to simultaneously tackle the challenges regarding step economy and selectivity. The early development of our hypothesis focuses on an iridium-catalyzed process efficient mainly with activated alcohols, which dictates harsh reaction conditions and thus limits its synthetic utility. Later, a significant advancement has been made on aliphatic primary alcohol deoxygenation by employing a ruthenium complex, with good functional group tolerance and exclusive selectivity under practical reaction conditions. Its synthetic utility is further illustrated by excellent efficiency as well as complete chemo- and regio-selectivity in both simple and complex molecular settings. Mechanistic discussion is also included with experimental supports. Overall, our current method successfully addresses the aforementioned challenges in the pertinent field, providing a practical redox-based approach to the direct sp3 C-O defunctionalization of aliphatic primary alcohols.
- Dai, Xi-Jie,Li, Chao-Jun
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supporting information
p. 5433 - 5440
(2016/05/19)
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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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- Selective synthesis of primary amines by reductive amination of ketones with ammonia over supported Pt catalysts
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Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the C£O stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
- Nakamura, Yoichi,Kon, Kenichi,Touchy, Abeda Sultana,Shimizu, Ken-Ichi,Ueda, Wataru
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p. 921 - 924
(2015/03/18)
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- Ring opening of pymisyl-protected aziridines with organocuprates
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The pyrimidine-2-sulfonyl (pymisyl) group is introduced as a new protecting group that can be used to activate aziridines towards ring opening. It is readily introduced and removed under mild conditions. Regioselective ring opening of pymisyl-protected 2-methyl-aziridine with organocuprates gives the corresponding sulfonamides in high yields, and the pymisyl group can subsequently be removed upon treatment with a thiolate. The versatility of this new nitrogen protecting group is illustrated with a new synthesis of Selegiline, a monoamine oxidase-B inhibitor marketed for the treatment of Parkinson's disease. Easy on'easy off: The pymisyl group is introduced as a new protecting group for the activation of aziridines towards ring opening with organocuprates (see scheme). It is readily removed under very mild conditions with thiolates. The versatility of the approach is illustrated in a new synthesis of Selegiline, a drug marketed for the treatment of Parkinson's disease.
- Bornholdt, Jan,Felding, Jakob,Clausen, Rasmus P.,Kristensen, Jesper L.
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supporting information; experimental part
p. 12474 - 12480
(2010/12/25)
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- 2-aminobenzoxazole derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminobenzoxazole derivative compounds of the following formula: wherein R1 to R4 and Z have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminobenzoxazole derivative compounds.
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- One-pot, new stereoselective synthesis of endo-tropanamine
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A palladium-catalysed reduction of ketones to primary amines by reaction with ammonium formate in aqueous methanol is described. The proposed method provides a one-pot synthesis of 3-endo-tropanamine in high yields and stereoselectivity.
- Allegretti, Marcello,Berdini, Valerio,Cesta,Curti, Roberto,Nicolini, Luca,Topai, Alessandra
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p. 4257 - 4259
(2007/10/03)
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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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- 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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