- Quaternary Charge-Transfer Complex Enables Photoenzymatic Intermolecular Hydroalkylation of Olefins
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Intermolecular C-C bond-forming reactions are underdeveloped transformations in the field of biocatalysis. Here we report a photoenzymatic intermolecular hydroalkylation of olefins catalyzed by flavin-dependent 'ene'-reductases. Radical initiation occurs via photoexcitation of a rare high-order enzyme-templated charge-transfer complex that forms between an alkene, α-chloroamide, and flavin hydroquinone. This unique mechanism ensures that radical formation only occurs when both substrates are present within the protein active site. This active site can control the radical terminating hydrogen atom transfer, enabling the synthesis of enantioenriched γ-stereogenic amides. This work highlights the potential for photoenzymatic catalysis to enable new biocatalytic transformations via previously unknown electron transfer mechanisms.
- Page, Claire G.,Cooper, Simon J.,Dehovitz, Jacob S.,Oblinsky, Daniel G.,Biegasiewicz, Kyle F.,Antropow, Alyssa H.,Armbrust, Kurt W.,Ellis, J. Michael,Hamann, Lawrence G.,Horn, Evan J.,Oberg, Kevin M.,Scholes, Gregory D.,Hyster, Todd K.
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supporting information
p. 97 - 102
(2021/01/12)
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- Non- C2-Symmetric Chiral-at-Ruthenium Catalyst for Highly Efficient Enantioselective Intramolecular C(sp3)-H Amidation
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A new class of chiral ruthenium catalysts is introduced in which ruthenium is cyclometalated by two 7-methyl-1,7-phenanthrolinium heterocycles, resulting in chelating pyridylidene remote N-heterocyclic carbene ligands (rNHCs). The overall chirality results from a stereogenic metal center featuring either a or Δabsolute configuration. This work features the importance of the relative metal-centered stereochemistry. Only the non-C2-symmetric chiral-at-ruthenium complexes display unprecedented catalytic activity for the intramolecular C(sp3)-H amidation of 1,4,2-dioxazol-5-ones to provide chiral -lactams with up to 99:1 er and catalyst loadings down to 0.005 mol % (up to 11 ?200 TON), while the C2-symmetric diastereomer favors an undesired Curtius-type rearrangement. DFT calculations elucidate the origins of the superior C-H amidation reactivity displayed by the non-C2-symmetric catalysts compared to related C2-symmetric counterparts.
- Zhou, Zijun,Chen, Shuming,Hong, Yubiao,Winterling, Erik,Tan, Yuqi,Hemming, Marcel,Harms, Klaus,Houk,Meggers, Eric
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supporting information
p. 19048 - 19057
(2019/12/04)
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- The organocatalytic highly enantioselective Knoevenagel condensation: applications in the synthesis of various chiral amide derivatives
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Abstract: In this work, efficient organocatalysts were designed, synthesized and successfully applied to the Knoevenagel condensation. In this reaction, different α-branched aldehydes were treated with various malonate compounds to give the desired produc
- Ashokkumar, Veeramanoharan,Siva, Ayyanar,Sankar, Balakrishnan
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p. 1939 - 1955
(2019/04/30)
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- Preparation method of carboxylic acid compound
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The invention provides a preparation method of a carboxylic acid compound. The preparation method comprises the following step of taking a lactone component to react with hydrogen in the presence of a compound catalyst to obtain the carboxylic acid compound. The compound catalyst comprises a hydrogenation catalyst and Lewis acid. In the presence of the compound catalyst comprising the hydrogenation catalyst and the Lewis acid, the lactone component is subjected to hydrogenation ring-opening reaction to obtain the carboxylic acid compound. The preparation method has the advantages of moderate reaction conditions and high yield; compared with a traditional method, less byproducts are generated, green and chemical requirements are met and the industrial value is better.
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Paragraph 0113; 0181-0183
(2017/08/29)
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- A Comprehensive Study on Metal Triflate-Promoted Hydrogenolysis of Lactones to Carboxylic Acids: From Synthetic and Mechanistic Perspectives
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Direct hydrogenolysis of lactone to carboxylic acid (i.e., hydrogenolysis of the Calkoxy-O bond with the carbonyl group untouched) is generally difficult, as the current strategies employing Br?nsted acids as the catalyst usually require harsh conditions such as a high temperature and a high H2 pressure. Herein, we report a developed solvent-free catalytic transformation, in which W(OTf)6 is believed to promote the hydrogenolysis process. This strategy could efficiently hydrogenate lactones to carboxylic acids under extra mild conditions (e.g., a reaction temperature of 2) and showed a broad substrate scope. In addition, the catalytic protocol can be further applied to the hydrogenolysis of polyhydroxyalkanoate, as a renewable polymer, to the corresponding straight-chain carboxylic acids. An extensive mechanistic study was subsequently performed, and the density functional theory calculations revealed a reaction pattern, including the complete cleavage of the C=O bond with the assistance of the W(OTf)6 catalyst. Moreover, the key intermediate created in the mechanism, as an oxonium with an OTf moiety, was successfully detected by electrospray ionization mass spectra. Through a comparison with the Br?nsted acid-catalyzed system, the study confirmed that the existence of the OTf moiety can significantly lower the barriers associated with the rearrangement and elimination processes. Meanwhile, emphasis was placed on the critical role that the anion plays, as well as the fact that the anion effect is directly related to the chemoselectivity.
- Zhu, Rui,Jiang, Ju-Long,Li, Xing-Long,Deng, Jin,Fu, Yao
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p. 7520 - 7528
(2017/11/10)
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- BETA-TETRAZOLYL-PROPIONIC ACIDS AS METALLO-BETA-LACTAMASE INHIBITORS
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The present invention relates to compounds of formula I that are metallo-β-lactamase inhibitors, the synthesis of such compounds, and the use of such compounds for use with β-lactam antibiotics for overcoming resistance.
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- Enantioselective iridium-catalyzed hydrogenation of β,γ- unsaturated carboxylic acids: An efficient approach to chiral 4-alkyl-4-aryl butanoic acids
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Chiral acids: A highly enantioselective iridium-catalyzed hydrogenation of β,γ-unsaturated carboxylic acids is developed for the preparation of chiral 4-alkyl-4-aryl butanoic acids (see scheme). Copyright
- Song, Song,Zhu, Shou-Fei,Yang, Shuang,Li, Shen,Zhou, Qi-Lin
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supporting information; experimental part
p. 2708 - 2711
(2012/04/17)
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- Chemoselective rhodium-carbenoid reaction with the aromatic nucleus: An efficient methodology for 2-indanones, 2- Tetralones and 2-benzosuberones and its application in the synthesis of (±)-ar-Himachalene
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Rhodium-carbenoid species derived from rhodium acetate- catalyzed decomposition of aryl alkyl α- diazoke-tones have been shown to display a chemoselective addition into the aromatic nucleus, instead of insertion into an aliphatic C-H site. The synthetic u
- Sudrik,Nanjundiah,Sonawane
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p. 1103 - 1112
(2007/10/03)
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- Direct Synthesis of Carboxylic Acids from Organoboranes
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Direct Synthesis of carboxylic acids through a two carbon atom homologation from organoboranes has been achieved, by the reaction with the dianion of phenoxyacetic acid.It is now possible to synthesize alkanoic, alkenoic, or alkynoic acids, from the corresponding alkenes, dienes, or enynes, respectively, via hydroboration.The reaction is tolerant of various functional groups present in alkenes, thus giving the corresponding carboxylic acids with chloro, sulfide, ether, acetal, and thioacetal functionalities in good yields.
- Hara, Shoji,Kishimura, Kotaro,Suzuki, Akira,Dhillon, Ranjit S.
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p. 6356 - 6360
(2007/10/02)
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- CYANOETHYLATION OF HYDROCARBONS, INITIATED BY AUTOOXIDATION
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Oxygen was used as an initiator of the free-radical cyanoethylation of alkylbenzenes (toluene, o-, m-, and p-xylenes, mesitylene, ethylbenzene, p-cymene) and tetralin (0.25-0.66 liter of oxygen to 1 liter of the hydrocarbon) The reactions were carried out in an autoclave at 150-350 deg C with a carbon-acrylonitrile ratio of 100:1.The initiation evidently results mainly from homolytic dissociation of the hydroperoxide formed during the autooxidation of the hydrocarbons.The effectiveness of oxygen for the initiation of the cyanoethylation of hydrocarbons depends on the oxidizability of the hydrocarbons.
- Galust'yan, G. G.
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p. 811 - 815
(2007/10/02)
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