- Palladium Catalysis for Aerobic Oxidation Systems Using Robust Metal–Organic Framework
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Described here is a new and viable approach to achieve Pd catalysis for aerobic oxidation systems (AOSs) by circumventing problems associated with both the oxidation and the catalysis through an all-in-one strategy, employing a robust metal–organic framework (MOF). The rational assembly of a PdII catalyst, phenanthroline ligand, and CuII species (electron-transfer mediator) into a MOF facilitates the fast regeneration of the PdII active species, through an enhanced electron transfer from in situ generated Pd0 to CuII, and then CuI to O2, trapped in the framework, thus leading to a 10 times higher turnover number than that of the homogeneous counterpart for Pd-catalyzed desulfitative oxidative coupling reactions. Moreover, the MOF catalyst can be reused five times without losing activity. This work provides the first exploration of using a MOF as a promising platform for the development of Pd catalysis for AOSs with high efficiency, low catalyst loading, and reusability.
- Li, Jiawei,Liao, Jianhua,Ren, Yanwei,Liu, Chi,Yue, Chenglong,Lu, Jiaming,Jiang, Huanfeng
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- Chemopreventive potential of cyclic diarylheptanoids.
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Eleven cyclic diarylheptanoids and seven related compounds were screened as potential antitumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. In addition, the cyclic diarylheptanoid myricanone (2) was examined for antitumor initiating activity in a two-stage carcinogenesis assay of mouse skin tumors induced by peroxynitrite as an initiator and TPA as a promoter. Myricanone (2) exhibited significant antitumor-initiating effect on mouse skin. These data suggest that cyclic, as well as linear, diarylheptanoids might be valuable chemopreventors.
- Ishida, Junko,Kozuka, Mutsuo,Tokuda, Harukuni,Nishino, Hoyoku,Nagumo, Seiji,Lee, Kuo Hsiung,Nagai, Masahiro
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- Activity and selectivity of W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus in organic solvents and ionic liquids: Mono- and biphasic media
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The asymmetric reduction of hydrophobic phenyl-ring-containing ketones and the enantiospecific kinetic resolution of the corresponding racemic alcohols catalyzed by Thermoanaerobacter ethanolicus W110A secondary alcohol dehydrogenase were performed in mono- and biphasic systems containing either organic solvents or ionic liquids. Both yield and enantioselectivity for these transformations can be controlled by changing the reaction medium. The enzyme showed high tolerance to both water-miscible and -immiscible solvents, which allows biotransformations to be conducted at high substrate concentrations. The Royal Society of Chemistry.
- Musa, Musa M.,Ziegelmann-Fjeld, Karla I.,Vieille, Claire,Phillips, Robert S.
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- Efficient and facile synthesis of novel stable monodeuterium labeled ractopamine
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A novel synthetic route to stable deuterium labeled ractopamine was disclosed with 6.49% total yield and 97.7% isotopic abundance. Its structure and the isotope-abundance were confirmed according to 1H-NMR and high-resolution mass spectrometry. A novel synthetic route to stable deuterium labeled ractopamine was disclosed with 9 steps, 6.49% total yield and 97.7% isotopic abundance. Its structure and the isotope-abundance were confirmed according to 1H-NMR and high-resolution mass spectrometry.
- Su, Feifei,Wu, Fulong,Tang, He,Wang, Zhonghua,Wu, Fanhong
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- Synthesis of α-Tertiary Amine Derivatives by Intermolecular Hydroamination of Unfunctionalized Alkenes with Sulfamates under Trifluoromethanesulfonic Acid Catalysis
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An efficient and mild trifluoromethanesulfonic acid-catalyzed hydroamination of unfunctionalized alkenes to afford α-tertiary amine derivatives at temperatures as low as room temperature is reported. 2,2,2-Trifluoroethyl sulfamate was found to be the optimal nitrogen source because its good solubility in both organic solvents and water facilitated both conversion and purification. The reaction conditions were compatible with a variety of substrate functional groups and afforded moderate to good yields. The desired amine compounds could be obtained easily by means of a mild, one-pot, redox-neutral deprotection procedure. Caryolane amine was synthesized with excellent chemo- and regioselectivities by means of a cascade hydroamination reaction of β-caryophyllene.
- Fei, Jun,Wang, Zhen,Cai, Zheren,Sun, Hao,Cheng, Xu
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- Cation-Exchanged Montmorillonite-Catalyzed Facile Friedel-Crafts Alkylation of Hydroxy and Methoxy Aromatics with 4-Hydroxybutan-2-one To Produce Raspberry Ketone and Some Pharmaceutically Active Compounds
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The Friedel-Crafts alkylation of hydroxy and methoxy aromatics with 4-hydroxybutan-2-one (γ-KB) in the presence of a cation-exchanged montmorillonite (M(n+)-mont; M(n+) = Zr(4+), Al(3+), Fe(3+), and Zn(2+)) was investigated.Phenol was C-alkylated regiospecifically with γ-KB in the presence of Zr(4+)-, Al(3+)-, or Fe(3+)-mont to produce 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone) in 31-35percent GLC yield.Anisole, 2-methoxynaphthalene, and 1-methoxynaphthalene were regiospecifically C-alkylated to produce 4-(4-methoxyphenyl)butan-2-one, 4-(2-methoxy-1-naphthyl)butan-2-one (pharmaceutically active), and 4-(4-methoxy-1-naphthyl)butan-2-one, respectively.Al(3+)- and Fe(3+)-mont were the most effective catalysts in these cases (13-58percent isolated yield). γ-KB could be used as an alkylating agent instead of the highly toxic 3-buten-2-one (MVK) which also polymerizes easily.
- Tateiwa, Jun-ichi,Horiuchi, Hiroki,Hashimoto, Keiji,Yamauchi, Takayoshi,Uemura, Sakae
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- A scalable two-step continuous flow synthesis of nabumetone and related 4-aryl-2-butanones
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Three different continuous flow strategies for the generation of important 4-aryl-2-butanone derivatives including the anti-inflammatory drug nabumetone [4-(6-methoxy-2-naphthalenyl)-2-butanone] and the aroma compounds raspberry ketone [4-(4-hydroxyphenyl)-2-butanone] and its methyl ether [4-(4-methoxyphenyl)-2-butanone] were evaluated. All three protocols involve the initial preparation of the corresponding 4-aryl-3-buten-2-ones via Mizoroki-Heck, Wittig, or aldol strategies, which is then followed by selective hydrogenation of the C=C double bond to the desired 4-aryl-2-butanones. The synthetic routes to 4-aryl-3-buten-2-ones were first optimized/intensified on small scale to reaction times of 1-10 min using batch microwave heating technology and then translated to a scalable continuous flow process employing commercially available stainless steel capillary tube reactors. For the synthesis of 4-(4-methoxyphenyl)-3-buten-2-one a further scale-up using a custom-built mesofluidic mini-plant flow system capable of processing several liters per hour was designed to further expand the scale of the process. The final hydrogenation step was performed using a fixed-bed continuous flow hydrogenator employing Ra/Ni as a catalyst.
- Viviano, Monica,Glasnov, Toma N.,Reichart, Benedik,Tekautz, Guenter,Kappe, C. Oliver
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- A chemoselective hydrogenation of the olefinic bond of α,β- unsaturated carbonyl compounds in aqueous medium under microwave irradiation
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A microwave-assisted mild and ecofriendly catalytic transfer hydrogenation process was developed to reduce various α,β-unsaturated carbonyl compounds into the corresponding saturated carbonyl compounds in the presence of silica-supported palladium chloride as catalyst and a combination of MeOH/HCOOH/H2O (1:2:3) as hydrogen source within 22-55 minutes in moderate to excellent yields with 100% chemoselectivity.
- Sharma, Anuj,Kumar, Vinod,Sinha, Arun K.
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- Iridium(I)-catalyzed regioselective C-H activation and hydrogen-isotope exchange of non-aromatic unsaturated functionality
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Isotopic labelling is a key technology of increasing importance for the investigation of new C-H activation and functionalization techniques, as well as in the construction of labelled molecules for use within both organic synthesis and drug discovery. Herein, we report for the first time selective iridium-catalyzed C-H activation and hydrogen-isotope exchange at the β-position of unsaturated organic compounds. The use of our highly active [Ir(cod)(IMes)(PPh3)][PF6] (cod = 1, 5-cyclooctadiene) catalyst, under mild reaction conditions, allows the regioselective β-activation and labelling of a range of α, β-unsaturated compounds with differing steric and electronic properties. This new process delivers high levels of isotope incorporation over short reaction times by using low levels of catalyst loading.
- Kerr, William J.,Mudd, Richard J.,Paterson, Laura C.,Brown, Jack A.
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- Synthesis and neuroprotective evaluation of (E)-3,4-dihydroxystyryl p-substituted-phenethyl ketone derivatives against inflammatory and oxidative injury
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(E)-3,4-dihydroxystyryl p-substituted-phenethyl ketones and their 3,4-diacetylated derivatives were synthesized and examined their neuroprotective activities to further study the effect of p-substituents on the aromatic ring. The results revealed that steric hindrance effect of p-substituents has impact on neuroprotective activities against inflammatory and oxidative injury. Introduction of the bulkier groups are more beneficial to improve the neuroprotective activities than smaller groups. Compounds (4–5h, 4–5i and 4–5e) with p-substituted trifluoromethyl, isopropyl and t-butyl groups exhibited the best effects among all the target compounds.
- Cheng, Can,Ning, Xianling,Luo, Yongming,Tian, Chao,Wang, Xiaowei,Guo, Ying,Liu, Junyi,Zhang, Zhili
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- Selectivity in palladium catalyzed arylation: Synthetic application leading to aromatized ionone natural products
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The selectivity in aromatic substitution vs conjugate addition during palladium catalyzed reactions has been controlled simply by changing the base. These reaction conditions have been applied to the syntheses of aromatized β-ionone natural products 1 and its dihydroderivatives 7.
- Hagiwara, Hisahiro,Eda, Yasushi,Morohashi, Kimie,Suzuki, Toshio,Ando, Masayoshi,Ito, Nobuhiko
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- H-type zeolite-catalyzed 1,4-addition of benzene derivatives to labile acrolein
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The 1,4-addition of benzene derivatives to acrolein is a straightforward way to synthesize 3-arylpropanals. A survey of acid catalysts for the 1,4-addition of methoxy-substituted benzenes to acrolein revealed that H-Beta and H-Y were the most suitable catalysts. We hypothesized three side-reactions: (1) the double 1,4-addition of acrolein to the starting benzene derivatives, (2) the Friedel-Crafts-type alkylation to the desired product, and (3) the self-polymerization of acrolein. The type (3) side-reaction was inhibited by two different methods which kept the concentration of acrolein low in the reaction mixture or in the zeolite pores. First, acrolein monomers were in situ generated through the gradual monomerization of an acrolein cyclic trimer. Second, using a reaction solvent lowered the acrolein concentration in the zeolite pores due to the competitive adsorption. We discovered that the content of monomeric acrolein in a solvent was closely related to the polarity of the solvent. Actually, both methods improved the yields for the 1,4-additions of 1,3-dimethoxybenzene to acrolein. Other electron-rich benzene derivatives, such as phenol and N, N-dimethylaniline, were also applicable to the 1,4-addition reactions.
- Hayashi, Daijiro,Narisawa, Tomoyuki,Masui, Yoichi,Onaka, Makoto
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- Asymmetric reduction and oxidation of aromatic ketones and alcohols using W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus
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An enantioselective asymmetric reduction of phenyl ring-containing prochiral ketones to yield the corresponding optically active secondary alcohols was achieved with W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus (W110A TESADH) in Tris buffer using 2-propanol (30%), v/v) as cosolvent and cosubstrate. This concentration of 2-propanol was crucial not only to enhance the solubility of hydrophobic phenyl ring-containing substrates in the aqueous reaction medium, but also to shift the equilibrium in the reduction direction. The resulting alcohols have S-configuration, in agreement with Prelog's rule, in which the nicotinamide-adenine dinucleotide phosphate (NADPH) cofactor transfers its pro-R hydride to the re face of the ketone. A series of phenyl ring-containing ketones, such as 4-phenyl-2-butanone (1a) and 1-phenyl-1,3-butadione (2a), were reduced with good to excellent yields and high enantioselectivities. On the other hand, 1-phenyl-2-propanone (7a) was reduced with lower ee than 2-butanone derivatives. (R)-Alcohols, the anti-Prelog products, were obtained by enantiospecific oxidation of (S)-alcohols through oxidative kinetic resolution of the rac-alcohols using W110A TESADH in Tris buffer/acetone (90:10, v/v).
- Musa, Musa M.,Ziegelmann-Fjeld, Karla I.,Vieille, Claire,Zeikus, J. Gregory,Phillips, Robert S.
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- Pd-aminoclay nanocomposite as an efficient recyclable catalyst for hydrogenation and suzuki cross coupling reactions
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A highly water dispersible Pd-aminoclay nanocomposite is found to be effective catalytic system for the hydrogenation of α,β-unsaturated carbonyl compounds and Suzuki coupling reactions in aqueous media. The catalytic hydrogenation of α,β-unsaturated carbonyl compounds proceeds at room temperature to afford the corresponding products in excellent yields with high chemoselectivity. The cross coupling of aryl bromides and iodides with aryl boronic acids proceeds efficiently under aqueous conditions at 90 °C to afford the corresponding biaryls in excellent yields with high selectivity. The Suzuki reaction proceeds smoothly even in the absence of external base due to the basic nature of the catalyst support. The catalyst could be easily recovered and recycled three times without a significant loss of activity in hydrogenation and Suzuki cross coupling reactions. Copyright
- Kumar, A. Sravanth,Datta,Rao, T. Srinivasa,Raghavan,Eswaramoorthy,Reddy, B.V. Subba
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- Cobalt bromide as catalyst in electrochemical addition of aryl halides onto activated olefins
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The consumable anode process permits the electrochemical arylation of activated olefins from functionalized aryl halides when cobalt halide is used as catalyst, either associated with bipyridine and pyridine as ligands in DMF as solvent, or with only pyridine in acetonitrile as solvent. (C) 2000 Published by Elsevier Science Ltd.
- Gomes, Paulo,Gosmini, Corinne,Nédélec, Jean-Yves,Périchon, Jacques
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- New synthesis of 1,4-diketones via rhodium-catalysed 1,4 carbonylative addition of arylboronic acids to α,β-unsaturated ketones
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The reaction of various arylboronic acids with α,β-unsaturated ketones under CO pressure and in the presence of rhodium catalyst yields 1,4-diketones.
- Sauthier, Mathieu,Castanet, Yves,Mortreux, Andre
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- A facile and chemoselective conjugate reduction using polymethylhydrosiloxane (PMHS) and catalytic B(C6F5) 3
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A highly chemoselective conjugate reduction of electron-deficient Michael acceptors, including Α, β-unsaturated ketones, carboxylic esters, nitriles and nitro compounds with PMHS in the presence of catalytic B(C 6F5)3 was investigated. When attempts were made to improve the yields by increasing the amount of catalyst, the result was a complex mixture of saturated and unsaturated compounds, with partial reduction of the ketone moiety to the methylene functionality. PMHS along with a catalytic amount of B(C6F5)3 was found to be a unique reagent system for the conjugate reduction of Michael acceptors.
- Chandrasekhar, Srivari,Chandrashekar, Gudise,Reddy, Marepally Srinivasa,Srihari, Pabbaraja
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- Palladium-catalyzed arylation of allylic alcohols with aryl iodides in water
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Palladium-catalyzed arylation of allylic alcohols with aryl iodides are shown to occur in the presence of sodium bicarbonate and tetra-n-butylammonium chloride in pure water using palladium acetate as catalyst. β-aromatic carbonyl compounds are obtained in good yields.
- Zhao,Cai,Hu,Song
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- Catalyzed Reactions of Enolates and Cations: A Novel Method for Enolate Alkylation
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The first tertiary alkylations, alkoxyalkylations, and aldehyde enolate allylations are described proceeding with low catalyst loading (0.1 mol % to 5 mol %). The reactions proceed in short times, can be performed without solvent and under ambient conditions.
- Gansaeuer, Andreas,Fielenbach, Doris,Stock, Christoph
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- Carbonylative 1,4-addition of potassium aryltrifluoroborates to vinyl ketones
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Potassium aryltrifluoroborates have proven to be useful reagents for the carbonylative aroylation of vinyl ketones; this study broadens the scope of potassium aryltrifluoroborates in homogeneous catalysis and shows that the solvent can act as the proton s
- Sauthier, Mathieu,Lamotte, Nicolas,Dheur, Julien,Castanet, Yves,Mortreux, Andre
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- 8-Hydroxyquinolin-2(1H)-one analogues as potential β2-agonists: Design, synthesis and activity study
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β2-Agonists that bind to plasmalemmal β2-adrenoceptors causing cAMP accumulation are widely used as bronchodilators in chronic respiratory diseases. Here, we designed and synthesized a group of 8-hydroxyquinolin-2(1H)-one analogues and studied their β2-agonistic activities with a cellular cAMP assay. Compounds B05 and C08 were identified as potent (EC50 2-agonists among the compounds tested. They behaved as partial β2-agonists in non-overexpressed HEK293 cells, and possessed rapid smooth muscle relaxant actions and long duration of action in isolated guinea pig tracheal strip preparations. In summary, B05 and C08 are β2-agonists with potential applicability in chronic respiratory diseases.
- Xing, Gang,Zhi, Zhengxing,Yi, Ce,Zou, Jitian,Jing, Xuefeng,Yiu-Ho Woo, Anthony,Lin, Bin,Pan, Li,Zhang, Yuyang,Cheng, Maosheng
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- Shuttle arylation by Rh(I) catalyzed reversible carbon–carbon bond activation of unstrained alcohols
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The advent of transfer hydrogenation and borrowing hydrogen reactions paved the way to manipulate simple alcohols in previously unthinkable manners and circumvented the need for hydrogen gas. Analogously, transfer hydrocarbylation could greatly increase the versatility of tertiary alcohols. However, this reaction remains unexplored because of the challenges associated with the catalytic cleavage of unactivated C–C bonds. Herein, we report a rhodium(I)-catalyzed shuttle arylation cleaving the C(sp2)–C(sp3) bond in unstrained triaryl alcohols via a redox-neutral β-carbon elimination mechanism. A selective transfer hydrocarbylation of substituted (hetero)aryl groups from tertiary alcohols to ketones was realized, employing benign alcohols as latent C-nucleophiles. All preliminary mechanistic experiments support a reversible β-carbon elimination/migratory insertion mechanism. In a broader context, this novel reactivity offers a new platform for the manipulation of tertiary alcohols in catalysis.
- Lutz, Marius D.R.,Gasser, Valentina C.M.,Morandi, Bill
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supporting information
p. 1108 - 1119
(2021/04/19)
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- Iron powder and tin/tin chloride as new reducing agents of Meerwein arylation reaction with unexpected recycling to anilines
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Simple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO2 from an excess of NaNO2/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture.
- Abdelwahab, Ahmed B.,El-Sawy, Eslam R.,Kirsch, Gilbert
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supporting information
p. 526 - 538
(2020/01/08)
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- One-Pot, Tandem Wittig Hydrogenation: Formal C(sp3)-C(sp3) Bond Formation with Extensive Scope
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A one-pot, tandem Wittig hydrogenation of aldehydes with stabilized ylides is reported, representing a formal C(sp3)-C(sp3) bond construction. The tandem reaction operates under mild conditions, is high yielding, and is broad in scope. Chemoselectivity for olefin reduction is observed, and the methodology is demonstrated in the synthesis of lapatinib analogues and a formal synthesis of (±)-cuspareine. Early insights suggest that the chemoselectivity observed in the reduction step is due to partial poisoning of the catalyst, after step one, thus adding to the power of the one-pot procedure.
- Devlin, Rory,Jones, David J.,Mcglacken, Gerard P.
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supporting information
p. 5223 - 5228
(2020/07/14)
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- Highly productive α-alkylation of ketones with alcohols mediated by an Ir-oxalamidato/solid base catalyst system
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An Ir-oxalamidato complex in combination with a solid base (e.g., magnesium aluminometasilicate/Ca(OH)2) significantly improved the catalyst productivity in α-alkylation of methyl ketones with primary alcohols. Optimization through systematic variation of the oxalamidato ligand led to a practical turnover number (TON) of 10 000.40 000.
- Maeda, Hironori,Nara, Hideki,Shimizu, Hideo
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supporting information
p. 2772 - 2779
(2020/12/29)
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- Direct Access to Isotopically Labeled Aliphatic Ketones Mediated by Nickel(I) Activation
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An extensive range of functionalized aliphatic ketones with good functional-group tolerance has been prepared by a NiI-promoted coupling of either primary or secondary alkyl iodides with NN2 pincer NiII-acyl complexes. The latter were easily accessed from the corresponding NiII-alkyl complexes with stoichiometric CO. This Ni-mediated carbonylative coupling is adaptable to late-stage carbon isotope labeling, as illustrated by the preparation of isotopically labelled pharmaceuticals. Preliminary investigations suggest the intermediacy of carbon-centered radicals.
- Donslund, Aske S.,Pedersen, Simon S.,Gaardbo, Cecilie,Neumann, Karoline T.,Kingston, Lee,Elmore, Charles S.,Skrydstrup, Troels
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supporting information
p. 8099 - 8103
(2020/03/16)
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- Deracemization and Stereoinversion of Alcohols Using Two Mutants of Secondary Alcohol Dehydrogenase from Thermoanaerobacter pseudoethanolicus
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We developed a one-pot sequential two-step deracemization approach to chiral alcohols using two mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). This approach relies on consecutive non-stereospecific oxidation of alcohols and stereoselective reduction of their prochiral ketones using two mutants of TeSADH with poor and good stereoselectivities, respectively. More specifically, W110G TeSADH enables a non-stereospecific oxidation of alcohol racemates to their corresponding prochiral ketones, followed by W110V TeSADH-catalyzed stereoselective reduction of the resultant ketone intermediates to enantiopure (S)-configured alcohols in up to > 99 percent enantiomeric excess. A heat treatment after the oxidation step was required to avoid the interference of the marginally stereoselective W110G TeSADH in the reduction step; this heat treatment was eliminated by using sol-gel encapsulated W110G TeSADH in the oxidation step. Moreover, this bi-enzymatic approach was implemented in the stereoinversion of (R)-configured alcohols, and (S)-configured alcohols with up to > 99 percent enantiomeric excess were obtained by this Mitsunobu-like stereoinversion reaction.
- Hamdan, Samir M.,Musa, Musa M.,Nafiu, Sodiq A.,Takahashi, Etsuko,Takahashi, Masateru
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- Preparation method of 4-p-hydroxyphenyl-2-butanone
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The invention discloses a preparation method of 4-p-hydroxyphenyl-2-butanone. The preparation method comprises the following steps of using anisaldehyde from a natural source as a raw material, preparing to obtain anisalcohol through a reduction reaction, preparing to obtain p-methoxybenzyl chloride through a chlorination reaction, next preparing to obtain 2-acetyl-3-(4-methoxyphenyl)ethyl propionate through a substitution reaction with ethyl acetoacetate from a biomass source, next preparing to obtain 4-(4-methoxyphenyl)-2-butanone through hydrolysis and decarboxylation reactions, and finallypreparing to obtain the 4-p-hydroxyphenyl-2-butanone through a demethylation reaction. The preparation method can be used for realizing the preparation of all-natural carbon-source raspberry ketone,and has the advantages of being simple and direct in route, easy to operate, environmentally friendly and high in yield and the like.
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Paragraph 0022; 0045; 0047; 0049; 0051; 0052; 0054
(2019/02/10)
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- Catalytic Generation and Use of Ketyl Radical from Unactivated Aliphatic Carbonyl Compounds
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Generation of a ketyl radical from unactivated aliphatic carbonyl compounds is an important strategy in organic synthesis. Herein, catalytic generation and use of a ketyl radical for the reductive coupling of aliphatic carbonyl compounds and styrenes by organic photoredox catalysis is described. The method is applicable to both aliphatic ketones and aldehydes to afford the corresponding tertiary and secondary alcohols in continuous flow and batch. Preliminary mechanistic investigation suggests the catalytic formation of a ketyl radical intermediate.
- Seo, Hyowon,Jamison, Timothy F.
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supporting information
p. 10159 - 10163
(2019/12/24)
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- Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor
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The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5867 - 5872
(2019/08/26)
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- Methanol as hydrogen source: Chemoselective transfer hydrogenation of α,β-unsaturated ketones with a rhodacycle
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Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.
- Aboo, Ahmed H.,Begum, Robina,Zhao, Liangliang,Farooqi, Zahoor H.,Xiao, Jianliang
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p. 1795 - 1799
(2019/11/11)
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- KETONES AND METHOD FOR MANUFACTURING ANALOG THEREOF
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PROBLEM TO BE SOLVED: To provide a technique for efficiently producing ketones by using cellulose after extracting chitin and chitosan extracted from the crustacean or sucrose from the beet in order to effectively using wastes, such as a crustacean or a beat to prepare a solid catalyst. SOLUTION: A method for manufacturing 1-phenyl-3-ketones and an analog (a compound 3) comprises using at least one kind selected from a group consisting of cellulose, chitin and chitosan as a carrier and reacting benzyl alcohols (a compound 1) with ketones (a compound 2) in the presence of a solid catalyst obtained by supporting a group 8-10 transition metal and a base. The following chemical formula 1 is shown. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0101; 0107-0109
(2019/04/05)
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- Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts
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It is shown how secondary alcohols are oxidized to provide the corresponding ketones by use of Oxone and solid-supported hypervalent iodine catalysts. Under experimentally simple conditions with acetonitrile at elevated temperatures, excellent conversions were achieved with low catalyst loadings (0.2-5 mol%) when employing the conjugates 5 and 6 derived from IBX and IBS. The catalysts are broadly applicable to a range of alcohol substrates. Of primary importance with respect to sustainability issues, the metal-free catalysts are easily removed from the reaction mixture through filtration, and they can be re-used in oxidation processes for multiple times, without loss of catalytic activity.
- Ballaschk, Frederic,Kirsch, Stefan F.
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supporting information
p. 5896 - 5903
(2019/11/11)
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- New photocatalytic fixed-point deuteration method for carbon-carbon unsaturated bonds
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The invention relates to a new photocatalytic fixed-point deuteration method for carbon-carbon unsaturated bonds. The method is characterized in that an olefin or alkyne compound and a deuterium source undergoes a deuteration reaction under the catalysis of a light source and a photocatalyst to obtain a deuterated product, wherein the deuterium source is deuterated water, deuterated alcohol or deuterated acid, and the reaction temperature is between room temperature and 80 DEG C. The fixed-point deuteration reaction of the olefin or alkyne compound is realized under the photocatalysis action of the photocatalyst with environmentally-friendly and cheap deuterated water or a deuteration reagent as a deuterium source to substitute deuterium gas. Compared with traditional deuteration reactions, the method has a higher selectivity, milder reaction conditions and higher economical suitability, and is suitable for large-scale deuterated chemical substance production.
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Paragraph 0055; 0057; 0058; 0061
(2019/01/21)
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- Rhenium-catalyzed α-alkylation of enol acetates with alcohols or ethers
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When benzylic and allylic alcohols were treated with enol acetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enol acetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonyl compounds were obtained in good yields. When ethers were used instead of alcohols as the alkylated agent, two alkyl moieties on the ethers were utilized on the reaction.
- Umeda, Rui,Takahashi, Yuuki,Yamamoto, Takaaki,Iseki, Hideki,Osaka, Issey,Nishiyama, Yutaka
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supporting information
p. 92 - 101
(2018/11/01)
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- Two efficient pathways for the synthesis of aryl ketones catalyzed by phosphorus-free palladium catalysts
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Allylic alcohols, 1-buten-3-ol, 1-penten-3-ol and 1-octen-3-ol, reacted with aryl iodides (iodotoluene, 4-iodotoluene, 4-iodophenol and 4-iodanisole) under Heck reaction conditions to form corresponding saturated aryl ketones in one step. The same products were obtained in a two-step tandem reaction consisted of the Heck coupling of allylic alcohols with aryl iodides, followed by hydrogenation. Reactions were catalyzed by phosphorus-free palladium precursors modified with the menthol-substituted imidazolium chlorides. Formation of crystalline palladium nanoparticles, of the diameter up to 65 nm, in the reaction mixture was evidenced by TEM.
- Wirwis,Feder-Kubis,Trzeciak
-
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- Simple Synthesis of Phytochemicals by Heterogeneous Pd- and Ir-Catalyzed Hydrogen-Borrowing C–C Bond Formation
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Chitin-supported palladium and iridium catalysts (i.e., Pd/chitin, Ir/chitin) successfully promote the hydrogen borrowing C–C bond formation reaction to afford phytochemicals and aroma compounds in excellent yields.
- Hori, Yoji,Suruga, Chiharu,Akabayashi, Yuta,Ishikawa, Tomoka,Saito, Marina,Myoda, Takao,Toeda, Kazuki,Maeda, Yuna,Yoshida, Yutaka
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supporting information
p. 7295 - 7299
(2018/01/02)
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- Multifunctional supported bimetallic catalysts for a cascade reaction with hydrogen auto transfer: Synthesis of 4-phenylbutan-2-ones from 4-methoxybenzyl alcohols
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We report the one-pot tandem synthesis of 4-(4-methoxyphenyl)butan-2-one directly from 4-methoxybenzyl alcohol and acetone using a multifunctional supported AuPd nanoalloy catalyst. This one-pot synthesis involves dehydrogenation, aldol condensation and hydrogenation of CC. In this supported AuPd catalyst, the bimetallic sites catalyse the dehydrogenation and hydrogenation steps and, in combination with the support, catalyse the C-C coupling (aldol) process. This supported bimetallic catalyst is also effective in utilizing hydrogen from the dehydrogenation reaction for the hydrogenation of 4-(4-methoxyphenyl)but-3-en-2-one to 4-(4-methoxyphenyl)butane-2-one via a hydrogen auto transfer route. These multifunctional catalysts were characterised using transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy.
- Morad, Moataz,Nowicka, Ewa,Douthwaite, Mark,Iqbal, Sarwat,Miedziak, Peter,Edwards, Jennifer K.,Brett, Gemma L.,He, Qian,Morgan, David,Alshammari, Hamed,Bethell, Donald,Knight, David W.,Sankar, Meenakshisundaram,Hutchings, Graham J.
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p. 1928 - 1936
(2017/07/15)
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- A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters
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We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron-deficient olefins via radical addition to efficiently form C?C coupled products in a redox-neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.
- Lima, Fabio,Sharma, Upendra K.,Grunenberg, Lars,Saha, Debasmita,Johannsen, Sandra,Sedelmeier, Joerg,Van der Eycken, Erik V.,Ley, Steven V.
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supporting information
p. 15136 - 15140
(2017/11/20)
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- Iridium(I) N-Heterocyclic Carbene (NHC)/Phosphine Catalysts for Mild and Chemoselective Hydrogenation Processes
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The directed chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity. The directed, chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity.
- Kerr, William J.,Mudd, Richard J.,Brown, Jack A.
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supporting information
p. 4738 - 4742
(2016/04/05)
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- Catalytic Ring-Opening of Cyclic Alcohols Enabled by PCET Activation of Strong O-H Bonds
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We report a new photocatalytic protocol for the redox-neutral isomerization of cyclic alcohols to linear ketones via C-C bond scission. Mechanistic studies demonstrate that key alkoxy radical intermediates in this reaction are generated via the direct homolytic activation of alcohol O-H bonds in an unusual intramolecular PCET process, wherein the electron travels to a proximal radical cation in concert with proton transfer to a weak Br?nsted base. Effective bond strength considerations are shown to accurately forecast the feasibility of alkoxy radical generation with a given oxidant/base pair.
- Yayla, Hatice G.,Wang, Huaiju,Tarantino, Kyle T.,Orbe, Hudson S.,Knowles, Robert R.
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supporting information
p. 10794 - 10797
(2016/09/09)
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- Deracemization of Secondary Alcohols by using a Single Alcohol Dehydrogenase
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We developed a single-enzyme-mediated two-step approach for deracemization of secondary alcohols. A single mutant of Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase enables the nonstereoselective oxidation of racemic alcohols to ketones, followed by a stereoselective reduction process. Varying the amounts of acetone and 2-propanol cosubstrates controls the stereoselectivities of the consecutive oxidation and reduction reactions, respectively. We used one enzyme to accomplish the deracemization of secondary alcohols with up to >99 % ee and >99.5 % recovery in one pot and without the need to isolate the prochiral ketone intermediate.
- Karume, Ibrahim,Takahashi, Masateru,Hamdan, Samir M.,Musa, Musa M.
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p. 1459 - 1463
(2016/05/02)
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- Sunlight-driven trifluoromethylation of olefinic substrates by photoredox catalysis: A green organic process
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The principles and utility of photoredox catalysis in organic synthesis are described. After a brief description of the features of the two types of catalytic photoredox processes following the reductive quenching cycle (RQC) and the oxidative quenching cycle (OQC), the discussion is focused on organic transformations based on OQC, in particular the trifluoromethylation of olefinic substrates with electrophilic trifluoromethylating reagents furnishing solvolytic addition products and substitution products. It is concluded that catalytic photoredox systems are green from the point of view of harmfulness, safety, and energy source (visible light, including sunlight). Future prospects of photoredox catalysis will be also discussed.
- Akita, Munetaka,Koike, Takashi
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p. 742 - 751
(2015/07/15)
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- Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase mutants with improved racemization activity
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Controlled racemization of enantiopure alcohols is a key step in dynamic kinetic resolution. We recently reported the racemization of enantiopure phenyl-ring-containing alcohols using W110A Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase (W110A TeSADH), which relies on selectivity mistakes. Trp-110 lines the large pocket of the active site of TeSADH, which allows W110A TeSADH mutant to accommodate phenyl-ring-containing substrates in Prelog mode, albeit with selectivity mistakes. Here, we report the racemization of enantiopure phenyl-ring-containing alcohols using several Trp-110 mutants of TeSADH in the presence of the oxidized and reduced forms of nicotinamide-adenine dinucleotide. We observed a noticeable enhancement in racemization efficiency when W110G TeSADH was used compared with W110Q, W110M, W110L, W110I, and W110V. This observation was anticipated because the W110G mutation is expected to open the large pocket of the active site to a greater extent compared to other mutants of TeSADH at W110. Both enantiomers of 1-phenyl-2-propanol and 4-phenyl-2-butanol were fully racemized by W110G TeSADH. We also constructed a triple mutant of TeSADH, W110A/I86A/C295A, by site-directed mutagenesis with the aim of opening the two pockets of the active site of TeSADH. The W110A/I86A/C295A mutant was employed to racemize enantiopure phenyl-ring-containing alcohols. The current study demonstrates that W110G and W110A/I86A/C295A TeSADH are more efficient catalysts for the racemization of enantiopure secondary alcohols than the previously reported mutant W110A TeSADH [6].
- Musa, Musa M.,Patel, Jay M.,Nealon, Christopher M.,Kim, Chang Sup,Phillips, Robert S.,Karume, Ibrahim
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supporting information
p. 155 - 159
(2015/03/30)
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- Oxidation and β-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands
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The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for C-C bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and β-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3)(cod)(MeIm(2- methoxybenzyl))][BF4] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0) of 1283 h-1, and also in the β-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new C-C bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde.
- Jiménez, M. Victoria,Fernández-Tornos, Javier,Modrego, F. Javier,Pérez-Torrente, Jesús J.,Oro, Luis A.
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supporting information
p. 17877 - 17889
(2015/12/08)
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- Rational design, synthesis and structure-activity relationships of 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues as novel tyrosinase inhibitors
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In continuing our program aimed to search for potent compounds as highly efficient tyrosinase inhibitors, here a series of novel 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues were designed, synthesized and their biological activities on mushroom tyrosinase were evaluated. Notably, most of compounds displayed remarkable tyrosinase inhibitory activities with IC50 value of lower than 1.0 μM. Furthermore, the structure-activity relationships (SARs) were discussed and the inhibition mechanism and the inhibitory kinetics of selected compounds 7k and 8d were also investigated. Taken together, these results suggested that such compounds could serve as the promising candidates for the treatment of tyrosinase-related disorders and further development of such compounds might be of great interest.
- You, Ao,Zhou, Jie,Song, Senchuan,Zhu, Guoxun,Song, Huacan,Yi, Wei
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p. 924 - 931
(2015/03/04)
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- Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols
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The reaction of enol acetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)5, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.
- Umeda, Rui,Takahashi, Yuuki,Nishiyama, Yutaka
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supporting information
p. 6113 - 6116
(2015/01/09)
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- Controlling olefin isomerization in the heck reaction with neopentyl phosphine ligands
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The use of neopentyl phosphine ligands was examined in the coupling of aryl bromides with alkenes. Di-tert-butylneopentylphosphine (DTBNpP) was found to promote Heck couplings with aryl bromides at ambient temperature. In the Heck coupling of cyclic alkenes, the degree of alkene isomerization was found to be controlled by the choice of ligand with DTBNpP promoting isomerization to a much greater extent than trineopentylphosphine (TNpP). Under optimal conditions, DTBNpP provides high selectivity for 2-aryl-2,3-dihydrofuran in the arylation of 2,3-dihydrofuran, whereas TNpP provided high selectivity for the isomeric 2-aryl-2,5-dihydrofuran. A similar complementary product selectivity is seen in the Heck coupling of cyclopentene. Heck coupling of 2-bromophenols or 2-bromoanilides with 2,3-dihydrofurans affords 2,5-epoxybenzoxepin and 2,5-epoxybenzazepins, respectively.
- Lauer, Matthew G.,Thompson, Mallory K.,Shaughnessy, Kevin H.
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p. 10837 - 10848
(2015/01/08)
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- Enantioselective oxidation of secondary alcohols by Candida parapsilosis ATCC 7330
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Optically pure allylic alcohols and 4-phenylbutan-2-ols were prepared by oxidative kinetic resolution using whole cells of Candida parapsilosis ATCC 7330. Only the 'S' enantiomer is selectively oxidized to the corresponding keto compound (yield, 37-46%) leaving the 'R' alcohol (yield, 37-52% and ee 46 to >99%). The biocatalytic method is carried out under mild conditions at 20°C, pH 6.5 in phosphate buffer.
- Sivakumari, Thakkellapati,Preetha, Radhakrishnan,Chadha, Anju
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p. 2257 - 2262
(2014/01/06)
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- Aerobic oxidative coupling between carbon nucleophiles and allylic alcohols: A strategy to construct β-(hetero)aryl ketones and aldehydes through hydrogen migration
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Wacker heck of a reaction: A highly efficient PdII-catalyzed intermolecular oxidative-coupling reaction is reported, inspired by the fundamental Heck and Wacker processes. The (hetero)aryl-PdX species, originating from C-H activation step or desulfonyl hydrazides, coupled with allylic alcohols by using oxygen as the sole oxidant (see scheme). Copyright
- Huang, Liangbin,Qi, Ji,Wu, Xia,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 15462 - 15466
(2013/11/19)
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- Palladium nanoparticles in glycerol: A versatile catalytic system for C-X bond formation and hydrogenation processes
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Palladium nanoparticles stabilised by tris(3-sulfophenyl)phosphine trisodium salt in neat glycerol have been synthesised and fully characterised, starting from both Pd(II) and Pd(0) species. The versatility of this innovative catalytic colloidal solution has been proved by its efficient application in C-X bond formation processes (X=C, N, P, S) and C-C multiple bond hydrogenation reactions. The catalytic glycerol phase could be recycled more than ten times, preserving its activity and selectivity. The scope of each of these processes has demonstrated the power of the as-prepared catalyst, isolating the corresponding expected products in yields higher than 90%. The dual catalytic behaviour of this glycerol phase, associated to the metallic nanocatalysts used in wet medium (molecular- and surface-like behaviour), has allowed attractive applications in one-pot multi-step transformations catalysed by palladium, such as C-C coupling followed by hydrogenation, without isolation of intermediates using only one catalytic precursor. Copyright
- Chahdoura, Faouzi,Pradel, Christian,Gomez, Montserrat
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p. 3648 - 3660
(2014/01/06)
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- Synthesis of β-aryl ketones by heck arylation of allylic alcohols catalysed by a MCM-41-supported bidentate nitrogen palladium complex
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The Heck arylation reaction of aryl iodides with allylic alcohols catalysed by an mesoporous silica (MCM-41)-supported bidentate nitrogen palladium complex [MCM-41-2N-Pd(OAc)2] proceeded smoothly in the presence of tetrabutylammonium chloride (TBAC) in DMF to afford β-aryl ketones in good to excellent yields. This heterogeneous palladium catalyst can be recovered by simple filtration and reused several times without any decrease in activity.
- Huang, Yixiang,Wang, Pingping,Liu, Jiaqin,Cai, Mingzhong
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p. 333 - 336
(2013/07/26)
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- Vinyl polymerization versus [1,3] O to C rearrangement in the ruthenium-catalyzed reactions of vinyl ethers with hydrosilanes
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Two reactions, vinyl polymerization and [1,3] O to C rearrangement of vinyl ethers, are investigated in the ruthenium-catalyzed reaction with hydrosilanes. The reaction pathways are dependent on the substituents of the vinyl ether, in particular, those of the alkoxy group. Primary-, secondary-, and tertiary-alkyl vinyl ethers, ROCHCH2, are polymerized with ease to give the corresponding polymer in good yields. When R is electron-donating benzyl groups, the reaction does not give the polyvinyl ether but results in [1,3] O to C rearrangement to give the corresponding aldehyde, RCH2CHO in moderate to good yields. The rearrangement selectively proceeds when vinyl ethers having α-substituents are used as the starting materials to give the corresponding ketones in high yields. With catalytic amounts of hydrosilanes, the rearrangement gives ketones or aldehydes selectively. In sharp contrast, use of excess amounts of hydrosilanes leads to the rearrangement followed by reduction of the formed carbonyl group to give the corresponding silyl ethers in good yields. Nature of catalytically active species is discussed. Crown Copyright
- Harada, Nari-Aki,Nishikata, Takashi,Nagashima, Hideo
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supporting information; experimental part
p. 3243 - 3252
(2012/06/01)
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- Malononitrile-assisted highly chemoselective bismuth triflate catalyzed conjugate reduction of α,β-unsaturated ketones
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A very simple, direct, bismuth-catalyzed conjugate reduction protocol that allows for the catalytic regioselective formation of substituted ketones from enones under mild conditions has been developed. We have shown for the first time that the combined poly(methylhydro)siloxane-malononitrile system can serve as an efficient reductant/reagent in 1,4-conjugate reduction of enones. The regioselectivity, efficiencies, and experimental simplicity of the present method complements the more complex methods previously employed in copper or palladium-catalyzed reduction. This method should prove attractive because of its mild reaction conditions and the interesting chemistry of combining the use of poly(methylhydro)siloxane and malononitrile for selective reduction. Copyright
- Shang, Jun-Yan,Li, Fei,Bai, Xing-Feng,Jiang, Jian-Xiong,Yang, Ke-Fang,Lai, Guo-Qiao,Xu, Li-Wen
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supporting information; scheme or table
p. 2809 - 2815
(2012/06/18)
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- A facile synthesis of 2h-chromenes and 9-functionalized phenanthrenes through reactions between α,β-unsaturated compounds and arynes
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Facile syntheses of 2H-chromenes or 9-functionalized phenanthrenes under mild conditions in moderate to good yields have been developed. They each involve annulations of arynes with α,β-unsaturated compounds bearing different electron-withdrawing groups (EWGs). Depending on the natures of the different EWGs, the reactions proceed by different pathways: enals react with arynes through a tandem [2+2] cycloaddition/thermal electrocyclic ring-opening/6e-electrocyclization sequence to afford 2H-chromenes, whereas acyl-/ethoxycarbonyl-/cyano-substituted styrenes undergo Diels-Alder reactions with arynes followed by aromatization to afford 9-functionalized phenanthrenes. The scope, limitations, regioselectivities and mechanisms have been studied and are discussed in detail. Depending on the natures of different EWGs in α,β-unsaturated compounds, the reactions between arynes and α,β-unsaturated compounds proceed by different tandem pathways to afford either 2H-chromenes or 9-functionalized phenanthrenes in a selective manner, which is of potential pharmaceutical interest.
- Zhang, Tiexin,Huang, Xian,Wu, Luling
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experimental part
p. 3507 - 3519
(2012/07/30)
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- Preparation, hydrogen bonds, and catalytic activity in metal-promoted addition of arylboronic acids to enones of a rhodium complex containing an NHC ligand with an alcohol function
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The complex RhCl(COD){3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazol-2- ylidene} has been prepared by reaction of the dimer [Rh(μ-OMe)(COD)] 2 with 3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazolium chloride and characterized by X-ray diffraction analysis. The structure reveals that 75% of the molecules are associated through intermolecular O-H...Cl hydrogen bonds between the OH group of the NHC substituent of one molecule and the chloride ligand of the adjacent molecule. This complex catalyzes the addition of arylboronic acids to cyclic and acyclic enones in anhydrous toluene. The alcohol function of the substituent of the NHC ligand plays the role assigned to water in previous cases.
- Penafiel, Itziar,Pastor, Isidro M.,Yus, Miguel,Esteruelas, Miguel A.,Olivan, Montserrat
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p. 6154 - 6161
(2012/10/29)
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- Oxidation with a photolabile carbonyl protecting group
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A novel oxidation approach utilizing a robust photolabile carbonyl protecting group reagent (1) as the oxidizing reagent has been developed. Different from existing methods, this approach oxidizes primary alcohols to the photosensitive acetals (e.g., 3), providing another unique approach to the protected aldehydes. Thus, for the first time, oxidation and protection are achieved in one reaction. Secondary alcohols are oxidized to the corresponding ketones. Moreover, the photolabile protecting group (PPG) also oxidizes ethers and esters. The oxidation is presumably via hydride abstraction by the tritylium ion generated from 1 under acidic conditions. However, the mechanisms for primary alcohols and secondary alcohols are slightly different.
- Yang, Haishen,Mu, Feng,Wang, Pengfei
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experimental part
p. 8955 - 8961
(2011/12/15)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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experimental part
p. 2981 - 2988
(2010/07/05)
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- New one-pot multistep process with multifunctional catalysts: Decreasing the e factor in the synthesis of fine chemicals
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The synthesis of a series of fine chemicals (4-(4-methoxyphenyl)-2- butanone, 4-(6,6-dimethylbicyclo[3,1,1]hept-2-en-2-yl)-2-butanone, and 2-cyclopentylcylopentanone) has been performed through a simple process that involves one-pot multi-step reactions (condensation-dehydration-reduction) using multifunctional base-acid-metal catalysts. The E factor for the specific process, as well as for the global process that includes the manufacturing of the reactants, has been calculated and compared with those obtained using conventional methods. In various cases, it is demonstrated that by means of process intensification with multifunctional solid catalysts, it is possible to decrease the E factor by one order of magnitude or more with respect to any of the manufacturing routes reported to date.
- Climent, Maria J.,Corma, Avelino,Iborra, Sara,Mifsud, Maria,Velty, Alexandra
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experimental part
p. 99 - 107
(2010/05/18)
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- PHOTO-ACTIVATABLE THERAPEUTIC AGENTS AND METHODS OF USING
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Novel photo-activatable pro-therapeutic agents and methods for their synthesis and use are described. The photo-activatable pro-therapeutic agents are inactive pro-forms of compounds that can be activated in situ, for example, by providing a pro-therapeutic agent to a subject and photo-activating the pro-therapeutic agent at a selected area of the subject. Also disclosed are methods for administering the photo-activatable pro-therapeutic agents to a subject then activating the pro-therapeutic agents at a selected area of the subject by exposing that area to light.
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Page/Page column 21
(2010/04/28)
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- Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds
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Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds is described. The rhodium-catalyzed reaction was carried out in aqueous N-methy-2-pyrrolidinone (NMP) to give 1,4-conjugate adduct exclusively, while t
- Kakusawa, Naoki,Yasuike, Shuji,Kurita, Jyoji
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experimental part
p. 1269 - 1283
(2010/10/03)
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