- Synthesis of trans-3-substituted cyclohexylamines via Br?nsted acid catalyzed and substrate-mediated triple organocatalytic cascade reaction
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We report a new organocatalytic cascade reaction. A combination of the amine substrate with a catalytic amount of a Br?nsted acid merges enamine and iminium catalysis with Br?nsted acid catalysis in a new organocatalytic cascade reaction. We found that the aniline substrate itself in combination with a catalytic amount of PTSA·H2O can function as an aminocatalyst accomplishing an aldol condensation-conjugate reduction cascade, which terminates in a Br?nsted acid catalyzed reductive amination incorporating the amine substrate into the final product. This transformation furnishes trans-3-substituted cyclohexyl amines in good yields and good diastereoselectivities. Georg Thieme Verlag Stuttgart.
- Zhou, Jian,List, Benjamin
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- Amino-Modified Silica-Supported Copper-Palladium Alloy. Synthesis and Use in Selective Hydrogenation of Disubstituted Nitroarenes in a Flow Micro Reactor
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A copper-palladium catalyst supported on amino-modified silica has been synthesized by chemical reduction. It has been found that submicron particles of a copper-palladium alloy are formed on the silica surface. Unlike commercially available palladium catalysts (Pd/Al2O3, Pd/C, Pd/BaSO4), the synthesized copper-palladium catalyst makes it possible to selectively reduce the nitro group in 3-nitrobenzaldehyde and 1-chloro-4-nitrobenzene.
- Nurmukhametova,Belov,Sultanova,Vorob’ev,Osin, Yu. N.,Burilov,Antipin
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- Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae
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Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C4–C8) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.
- Matzel, Philipp,Krautschick, Lukas,H?hne, Matthias
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p. 2022 - 2027
(2017/10/07)
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- CATALYST COMPOUNDS
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The present invention relates to an iridium-based catalyst compound for hydrogenating reducible moieties, especially imines and iminiums, the catalyst compounds being defined by the formulas: where ring B is either itself polycyclic, or ring B together with R is polycyclic. The catalysts of the invention are particularly effective in reductive amination procedures 10 which involve the in situ generation of the imine or iminium under reductive hydrogenative conditions.
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Paragraph 0314; 0322
(2015/03/28)
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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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- CATALYST COMPOUNDS
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The present invention relates to an iridium-based catalyst compound for hydrogenating reducible moieties, especially imines and iminiums, the catalyst compounds being defined by the formulas: where ring B is either itself polycyclic, or ring B together with R is polycyclic. The catalysts of the invention are particularly effective in reductive amination procedures 10 which involve the in situ generation of the imine or iminium under reductive hydrogenative conditions.
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Paragraph 00163; 00171
(2013/11/05)
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- Synthesis of amides with anti-inflammatory and analgesic activities
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A series of N-Aroyl-cyclohexyl- and cyclohexenylamides 3- or 4- methylsubstituted were synthesized and evaluated for their anti-inflammatory and analgesic potencies, and gastrointestinal irritation liability. One compound, N-benzoyl-4-methyl-cyclohexylamide 6a, possessed an anti- inflammatory activity comparable to that of indomethacin.
- Pau,Cerri,Boatto,Palomba,Pintore,Filippelli,Falcone,Palagiano,Rossi
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- Catalytic reduction of the arene ring, and other functionalities, of organic substrates using formic acid and palladium on carbon
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The arene ring in a variety of compounds with functionalities which contain nitrogen is reduced in good yields using formic acid and Pd/C in methanol.
- Alper, Howard,Vampollo, Guiseppe
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p. 7477 - 7480
(2007/10/02)
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- Synthesis of analogues of N (2 chloroethyl) N' trans 4 methylcyclohexyl) N nitrosourea for evaluation as anticancer agents
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The superior activity of N (2 chloroethyl) N' (trans 4 methylcyclohexyl) N nitrosourea (MeCCNU) against advanced murine Lewis lung carcinoma in comparisons with the cis form and other nitrosoureas prompted the synthesis of a number of MeCCNU analogues, including several cis trans pairs. The methyl group was replaced by a variety of substituents (CO2H, CH2CO2H, CO2Me, CH2OAc, CH2Cl, OMe); the trans 3 methylcyclohexyl, cis 2 methyl 1,3 dithian 5 yl, cis and trans 2 methyl 1,3 dithian 5 yl tetraoxide, and 1 methylhexyl (open chain) analogues were also prepared. Preliminary tests against murine leukemia L1210 revealed therapeutic indices (ED50/LD10) ranging from 0.26 to 0.79; all but 3 analogues effected 50% cure rates at nontoxic doses, the open chain analogue being one of the least active. In terms of therapeutic index, diequatorial (trans 4) isomers were, with one exception, as active as or, in 4 of the 8 examples, somewhat more active than the corresponding axial equatorial (cis 4) isomers. In this series, 4 of the 5 2-fluoroethyl analogues prepared were clearly inferior to the corresponding 2 chloroethyl analogues.
- Johnston,McCaleb,Clayton,Frye,Krauth,Montgomery
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p. 279 - 290
(2007/10/04)
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