- Asymmetric Organocatalysis and Continuous Chemistry for an Efficient and Cost-Competitive Process to Pregabalin
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Herein, we present the scale up development of an innovative synthetic process to pregabalin. The process is underpinned by two enabling technologies critical to its success; continuous chemistry allowed a safe and clean production of nitroalkene, and asymmetric organocatalysis gave access to the chiral intermediate in an enantioenriched form. Crucial to the success of the process was the careful development of a continuous process to nitroalkene and optimization of the organocatalyst and of the reaction conditions to attain remarkably high turn-over frequency in the catalytic asymmetric reaction. Successful recycle of the organocatalysts was also developed in order to achieve a cost-competitive process.
- Bernardi, Luca,Carlone, Armando,Cobley, Christopher J.,Mccormack, Peter,Oruganti, Srinivas,Warr, Tony
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p. 2795 - 2805
(2021/12/13)
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- Preparation of a magnetic mesoporous Fe3O4-Pd@TiO2 photocatalyst for the efficient selective reduction of aromatic cyanides
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Herein, a hierarchical magnetic mesoporous microsphere was successfully prepared as a photocatalyst via a simple and reproducible route. Typically, Pd nanoparticles (NPs) were evenly dispersed on the surface of a magnetic Fe3O4 microsphere and then coated with a porous anatase-TiO2 shell to form Fe3O4-Pd@TiO2. The core-shell structure could efficiently suppress the conglomeration of Pd NPs during the calcination process at high temperatures as well as the shedding of Pd during the catalytic reaction process in the liquid phase. The as-prepared photocatalyst was characterized by TEM, XRD, XPS, VSM, and N2 adsorption-desorption. Fe3O4-Pd@TiO2 exhibits high photocatalytic activity for the selective reduction of aromatic cyanides to aromatic primary amines in an acidic aqueous solution. Moreover, this magnetic photocatalyst could be easily recovered from the reaction mixture by an external magnet and reused five times without significant reduction in its activity. The superior photocatalytic efficiency of the proposed photocatalyst may be attributed to its high charge separation efficiency and charge transfer rate, which are caused by the Schottky junction and large interface area. The results indicate that the strategy of coating the active noble metal sites with a mesoporous semiconductor shell has a significant potential for application in metal-semiconductor-based photocatalytic reactions.
- Zhao, Ziming,Long, Yu,Luo, Sha,Wu, Wei,Ma, Jiantai
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p. 6294 - 6302
(2019/04/25)
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- Cobalt-based nanoparticles prepared from MOF-carbon templates as efficient hydrogenation catalysts
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The development of efficient and selective nanostructured catalysts for industrially relevant hydrogenation reactions continues to be an actual goal of chemical research. In particular, the hydrogenation of nitriles and nitroarenes is of importance for the production of primary amines, which constitute essential feedstocks and key intermediates for advanced chemicals, life science molecules and materials. Herein, we report the preparation of graphene shell encapsulated Co3O4- and Co-nanoparticles supported on carbon by the template synthesis of cobalt-terephthalic acid MOF on carbon and subsequent pyrolysis. The resulting nanoparticles create stable and reusable catalysts for selective hydrogenation of functionalized and structurally diverse aromatic, heterocyclic and aliphatic nitriles, and as well as nitro compounds to primary amines (>65 examples). The synthetic and practical utility of this novel non-noble metal-based hydrogenation protocol is demonstrated by upscaling several reactions to multigram-scale and recycling of the catalyst.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Sohail, Manzar,Alshammari, Ahmad S.,Pohl, Marga-Martina,Beller, Matthias,Jagadeesh, Rajenahally V.
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p. 8553 - 8560
(2018/11/30)
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- Versatile Dynamic Covalent Assemblies for Probing π-Stacking and Chirality Induction from Homotopic Faces
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Herein we report for the first time the use of dynamic covalent reactions (DCRs) for building a π-stacking model system and further quantifying its substituent effects (SEs), which remain a topic of debate despite the rich history of stacking. A general DCR between 10-methylacridinium ion and primary amines was discovered, in which π-stacking played a stabilizing role. Facile quantification of SEs with in situ competing π-stacking systems was next achieved in the form of amine exchange exhibiting structural diversity by simply varying components. The linear correlation with σm in Hammett plots indicates the dominance of purely electrostatic SEs, and the additivity of SEs is in line with the direct interaction model. With α-chiral amines π-stacking within the adduct enabled chirality transfer from homotopic faces. The strategy of dynamic covalent assembly should be appealing to future research of probing weak interactions and manipulating chirality.
- Ye, Hebo,Hai, Yu,Ren, Yulong,You, Lei
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supporting information
p. 3804 - 3809
(2017/03/27)
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- HIGH-PURITY (FLUOROALKYL)BENZENE DERIVATIVE AND PROCESS FOR PRODUCING THE SAME
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The process for producing a (fluoroalkyl)benzene derivative according to the present invention comprises a step of reducing the total content of group 3 to group 12 transition metals in an alkylbenzene derivative to 500 ppm or less in terms of metal atoms; a step of halogenating the branched alkyl group of the purified alkylbenzene derivative by a photohalogenation to obtain a (haloalkyl)benzene derivative; and a step of subjecting the (haloalkyl)benzene derivative to a halogen-fluorine exchange using HF in an amount of 10 mol or higher per one mole of the (haloalkyl)benzene derivative. The (fluoroalkyl)benzene derivative produced by the process is reduced in the content of impurities such as residual halogens and residual metals, and is useful as intermediates for functional chemical products for use in applications such as medicines and electronic materials.
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- Highly regioselective hydrogenolysis of bis(α-methylbenzyl)amine derivatives affected by the trifluoromethyl substituent on the aromatic ring
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(Matrix presented) The highly regioselective hydrogenolysis of bis(α-methylbenzyl)amine derivatives proceeded with influence not from the electronic effect but from the steric effect of the trifluoromethyl substituent on the aromatic ring to provide a practical asymmetric synthesis of trifluoromethyl-substituted α-phenylethylamines.
- Kanai, Masatomi,Yasumoto, Manabu,Kuriyama, Yokusu,Inomiya, Kenjin,Katsuhara, Yutaka,Higashiyama, Kimio,Ishii, Akihiro
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p. 1007 - 1010
(2007/10/03)
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- Process for producing aromatic primary amine by low-pressure
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A method for producing an aromatic primary amine, characterized by hydrogenating an aromatic nitrile at a low partial pressure of hydrogen in a heterogeneous system comprising a non-reductive polar solvent and a nickel-immobilized catalyst suspended therein was proposed. By such method, an aromatic primary amine which is industrially useful as a medicine, agricultural chemical, dye surfactant, chemical agent, etc. can be produced in a high yield.
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- Process for producing trifluoromethylbenzylamines
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The invention relates to a process for producing a trifluoromethylbenzylamine represented by the following general formula (1), where each R independently represents a halogen selected from the group consisting of fluorine, chlorine, bromine and iodine, an alkyl group having a carbon atom number of 1-4, an alkoxy group having a carbon atom number of 1-4, an amino group, a hydroxyl group or a trifluoromethyl group, and n represents an integer from 0 to 4. The process includes hydrogenating a trifluoromethylbenzonitrile by hydrogen in an organic solvent in the presence of ammonia and a catalyst containing a platinum group element. This trifluoromethylbenzonitrile is represented by the following general formula (2), where R and n are defined as above. With this process, it is possible to obtain the trifluoromethylbenzylamine at an extremely high yield.
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- Process for producing trifluoromethylbenzylamines
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The present invention relates to a process for producing a trifluoromethylbenzylamine represented by the general formula (1). This process includes the step of reducing an oxime represented by the general formula (2), where R1represents hydrogen atom, a halogen atom selected from the group consisting of fluorine, chlorine, bromine and iodine, or trifluoromethyl group, where R1is defined as above, and R2represents hydrogen atom, an alkyl group or an aralkyl group. With this process, the trifluoromethylbenzylamine can be produced with high selectivity.
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- Process for producing trifluoromethylbenzylamines
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The invention relates to a process for producing a trifluoromethylbenzylamine represented by the following general formula (1). This process includes hydrogenating a trifliuoromethylbenzonitrile represented by the following general formula (2) by hydrogen in an organic solvent in the presence of ammonia, using a Raney catalyst, where each R independently represents a halogen selected from the group consisting of fluorine, chlorine, bromine and iodine, an alkyl group having a carbon atom number of 1-4, an alkoxy group having a carbon atom number of 1-4, an amino group, a hydroxyl group or a trifluoromethyl group, and n represents an integer from 0 to 4, where R and n are defined as above. With this process, it is possible to obtain the trifluoromethylbenzylamine easily and inexpensively at an extremely high yield.
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- Supported nickel-catalyzed hydrogenation of aromatic nitriles under low pressure conditions
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Hydrogenation of aromatic nitriles takes place under the mild conditions using supported nickel catalysts to afford amino-methyl-substituted aromatics in good yields.
- Takamizawa,Wakasa,Fuchikami
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p. 1623 - 1625
(2007/10/03)
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