- Synthesis of Chiral Amines via a Bi-Enzymatic Cascade Using an Ene-Reductase and Amine Dehydrogenase
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Access to chiral amines with more than one stereocentre remains challenging, although an increasing number of methods are emerging. Here we developed a proof-of-concept bi-enzymatic cascade, consisting of an ene reductase and amine dehydrogenase (AmDH), to afford chiral diastereomerically enriched amines in one pot. The asymmetric reduction of unsaturated ketones and aldehydes by ene reductases from the Old Yellow Enzyme family (OYE) was adapted to reaction conditions for the reductive amination by amine dehydrogenases. By studying the substrate profiles of both reported biocatalysts, thirteen unsaturated carbonyl substrates were assayed against the best duo OYE/AmDH. Low (5 %) to high (97 %) conversion rates were obtained with enantiomeric and diastereomeric excess of up to 99 %. We expect our established bi-enzymatic cascade to allow access to chiral amines with both high enantiomeric and diastereomeric excess from varying alkene substrates depending on the combination of enzymes.
- Fossey-Jouenne, Aurélie,Jongkind, Ewald P. J.,Mayol, Ombeline,Paul, Caroline E.,Vergne-Vaxelaire, Carine,Zaparucha, Anne
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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
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supporting information
p. 6216 - 6226
(2020/04/27)
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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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- The evolution of an amine dehydrogenase biocatalyst for the asymmetric production of chiral amines
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The reductive amination of ketones to produce chiral amines is an important transformation in the production of pharmaceutical intermediates. Therefore, industrially applicable enzymatic methods that enable the selective synthesis of chiral amines could be very useful. Using a phenylalanine dehydrogenase scaffold devoid of amine dehydrogenase activity, a robust amine dehydrogenase has been evolved with a single two-site library allowing for the direct production of (R)-1-(4-fluorophenyl)-propyl-2-amine from para- fluorophenylacetone with a kcat value of 6.85 s-1 and a KM value of 7.75 mM for the ketone substrate. This is the first example of a highly active amine dehydrogenase capable of accepting aliphatic and benzylic ketone substrates. The stereoselectivity of the evolved amine dehydrogenase was very high (>99.8% ee) showing that high selectivity of the wild-type phenylalanine dehydrogenase was conserved in the evolution process. When paired with glucose/glucose dehydrogenase, NADH cofactor can be effficiently regenerated and the reaction driven to over 93% conversion. The broad specificity, high selectivity, and near complete conversion render this amine dehydrogenase an attractive target for further evolution toward pharmaceutical compounds and subsequent application. Copyright
- Abrahamson, Michael J.,Wong, John W.,Bommarius, Andreas S.
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p. 1780 - 1786
(2013/07/19)
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- Process and intermediate to prepare N-alkyl-3,4-dialkyl-2,6-dinitro-anilines
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The intermediate STR1 wherein R is a lower alkyl group, is used to prepare a N-alkyl-3,4-dialkyl-2,6,-dinitro-aniline in a relatively simple, inexpensive and safe fashion, and with a high yield.
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- Linear dicarbonylation of difunctionalized butenes
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Difunctional butenes are linearly dicarbonylated into 3-hexene-1,6-dioic acid or alkyl diesters thereof, well suited for the ultimate production of, e.g., adipic acid, by reacting such difunctional butene with carbon monoxide and, if appropriate, an alcohol, at an elevated temperature under superatmospheric pressure, in the presence of at least one source of hydrogen chloride and a catalytically effective amount of palladium, at least a portion of which palladium being in the zero oxidation state, as well as a quaternary onium chloride of nitrogen or phosphorus, the nitrogen or phosphorus atom being tetracoordinated to carbon atoms, with the proviso that the nitrogen atom may be coordinated to two pentavalent phosphorus atoms.
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- Novel process to prepare N-alkyl-3,4-dialkyl-2,6-dinitroanilines
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A process is provided for preparing N-alkyl-3,4-dialkyl-2,6-dinitroanilines of the formula Wherein R1 is hydrogen, C1 to C6 straight or branched chain alkyl group; and, R2, R3 and R4 are independently C1 to C6 straight or branched chain alkyl group optionally substituted by one or more halogen groups, wherein a. 3,4-dialkyl phenol of the formula is selectively nitrated with nitric acid in a two phase system to form 3,4-dialkyl-2,6-dinitrophenol of the formula: b. the 3,4-dialkyl-2,6-dinitrophenol is alkylated with an alkylating agent in the presence of a base and a catalytic amount of a phase transfer catalyst chosen from the group consisting of, , (R')4Q X-, , wherein R' may be the same or different C1 to C16 straight or branched alkyl groups, benzyl, substituted benzyl; Qis N or P; and Xis CL, Br, I or HSO4; a macrocyclic ether and polyethylene glycols of formula, , HO - (CH2CH2O-)n-CH2CH2OH, , where n is an integer from 10 to 50, in an organic solvent to form 3,4-dalkyl-2,6-dinitro alkoxybenzene of the formula: where R5 is an alkyl group having 1 to 6 carbon atoms. c. the 3,4-dialkyl-2,6-dinitro alkoxybenzene is reacted with an amine of the formula where R1 and R2 are defined above, in the presence of a catalytic amount of base or halide to form N-alkyl-3,4-dialkyl-2,6-dinitroaniline. d. the N-alkyl-3,4-dialkyl-2,6-dinitroaniline is recovered.
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- Process for preparing amines from olefins with ammonium halide catalysts
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The process for preparing aliphatic and aromatic amines by reacting an olefin with either ammonia, a primary amine, or a secondary amine at elevated temperature in the presence of an ammonium halide catalyst, preferably a catalyst-promoter combination, is disclosed herein.
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- Very Soluble and Photostable Perylene Fluorescent Dyes
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The synthesis of perylene dyes 2 with two terminal alkyl groups is described.Long-chain alkyl groups do not increase, but diminish solubility.Cycloalkyl substituents give a minimum of solubility with medium sized rings and a maximum with the cyclotetradecyl derivative (2p).Very high solubility in organic solvents is attained by substitution with secondary alkyl residues having two long chains.One of them, the dye with the 1-hexylheptyl substituent (2v), exhibits a solubility of more than 100g/l in most solvents, a fluorescent quantum yield of about 100 percent, and a very high photostability, thus making it suitable for special applications.
- Demming, Stefan,Langhals, Heinz
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p. 225 - 230
(2007/10/02)
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- Preparation of amines from olefins using certain transition metal catalysts
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Aliphatic and aromatic amines are produced by reacting an olefin with either ammonia or a primary or secondary amine in the presence of a catalytic amount of ruthenium or iron compound catalyst. The reaction is carried out in the liquid phase using an inert liquid, a product amine, or one of the reactants as a solvent. The temperatures used are 100° to 250° C. and the pressures are at least autogenous and up to 12,000 psig.
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- Classical Carbonium Ions. Part 13. Rearrangements from Secondary to Primary Alkyl Groups during Reactions involving Carbonium Ions
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The rearrangement of cyclohexylamine to cyclopentylmethyl derivatives, earlier reported in brief, is confirmed.A similar reaction with 4-trans-t-butylcyclohexylamine is shown to give trans-3-t-butylcyclopentylmethyl derivatives, defining the conformational requirements and stereochemical course of the rearrangement.In similar reactions 2-butylamine and 3-pentylamine give, in small yield, derivatives of primary alcohols.Cyclohexyl toluenesulphonate probably gives a very small yield of cyclopentylmethyl acetate.All these reactions involve the formation of products formally derived from carbonium ions much less stable than those initially generated, and yields, though small, are much larger than can be accounted for by classical descriptions.It is proposed that corner-protonated cyclopropanes ('non-classical carbonium ions') are 'intermediates' of very short lifetime in these reactions; the extent to which it is possible to regard species of very short lifetime as intermediates is discussed.
- Cooper, Catherine N.,Jenner, Peter J.,Perry, Nigel B.,Russel-King, Jonquil,Storesund, Hans J.,Whiting, Mark C.
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p. 605 - 612
(2007/10/02)
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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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