- 2-Indanone and Its Enol. The Effect of a Conjugated Phenyl Group on Enol and Enolate Stability
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Rate and equilibrium constants for the interconversion of 2-indanone with its enol and enolate ion have been determined in dilute aqueous acid and base solution (ionic strength=0.10 M) at 25 deg C.These measurements provide the keto-enol equilibrium constant, pKE=3.84+-0.04; the acidity constant of the ketone ionizing as a carbon acid, pKaK=12.20+-0.08; and the acidity constant of the enol ionizing as an oxygen acid, pKaE=8.36+-0.09.Comparison of these results with values for acetone show that the effects of the benzene ring are large: a factor of 1E4.4 on KE, 1E7.0 on KaK, and 1E2.6 on KaE.Considerably smaller phenyl effects are estimated for the acyclic model ketone phenylacetone; reduced coplanarity in the latter is suggested as the major reason for the reduced effects.In terms of rate constants,the greater enol content of 2-indanone relative to acetone manifests itself in the acid-catalyzed reaction mainly as a largely reduced rate of enol ketonization and in the "uncatalyzed" reaction entirely by an increased rate of enolization.For hydroxide ion promoted enolate formation the phenyl effect appears roughly equally as an increase in the rate of enolate formation and a decrease in ketonization rate.It is suggested that the effects of a conjugated benzene ring on enol and enolate stability are fully expressed by the reactions of 2-indanone.
- Keeffe, J.R.,Kresge, A.J.,Yin, Y.
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Read Online
- Discovery, biological evaluation, and crystal structure of a novel nanomolar selective butyrylcholinesterase inhibitor
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Butyrylcholinesterase (BChE) is regarded as a promising drug target as its levels and activity significantly increase in the late stages of Alzheimer's disease. To discover novel BChE inhibitors, we used a hierarchical virtual screening protocol followed by biochemical evaluation of 40 highest scoring hit compounds. Three of the compounds identified showed significant inhibitory activities against BChE. The most potent, compound 1 (IC50 = 21.3 nM), was resynthesized and resolved into its pure enantiomers. A high degree of stereoselective activity was revealed, and a dissociation constant of 2.7 nM was determined for the most potent stereoisomer (+)-1. The crystal structure of human BChE in complex with compound (+)-1 was solved, revealing the binding mode and providing clues for potential optimization. Additionally, compound 1 inhibited amyloid β1-42 peptide self-induced aggregation into fibrils (by 61.7% at 10 μM) and protected cultured SH-SY5Y cells against amyloid-β-induced toxicity. These data suggest that compound 1 represents a promising candidate for hit-to-lead follow-up in the drug-discovery process against Alzheimer's disease.
- Brus, Boris,Ko?ak, Urban,Turk, Samo,Pi?lar, Anja,Coquelle, Nicolas,Kos, Janko,Stojan, Jure,Colletier, Jacques-Philippe,Gobec, Stanislav
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Read Online
- Ironcarbonyl Complexes of 5,6-Dimethylidene-7-oxabicyclohept-2-ene Derivatives. Synthesis of Substituted Tricarbonyl(ortho-quinodimethane)iron Complexes and 2-Indanones
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The 1-dimethoxymethyl-5,6-dimethylidene-7-oxabicyclohept-2-ene (9) has been prepared.On treatment with Fe2(CO)9, the endocyclic double bond C(2)=C(3) was coordinated first giving the corresponding exo-Fe(CO)4 complex 10.The latter reacted with Fe2(CO)9 and afforded cis heptacarbonyl-μ-hept-2-ene)>diiron (11) as a major product.On heating, 11 undervent deoxygenation of the 7-oxabicycloheptene moiety yielding tricarbonyliron (13).In MeOH, a concurrent, regioselective methoxycarbonylation was observed giving tricarbonyliron (14).Oxidative removal of the Fe(CO)3 moiety in 13 and 14 did not afford the expected ortho-quinodimethane derivatives but led to CO insertions giving 2,3-dihydro-2-oxo-1H-indene-4-carbaldehyde (2) and methyl 7-formyl-2,3-dihydro-2-oxo-1H-indene-5-carboxylate (21), respectively.
- Bonfantini, Edia,Metral, Jean-Luc,Vogel, Pierre
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Read Online
- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
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Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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supporting information
p. 8738 - 8741
(2021/09/08)
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- Bidentate Nitrogen-Ligated I(V) Reagents, Bi(N)-HVIs: Preparation, Stability, Structure, and Reactivity
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Hypervalent iodine(V) reagents are a powerful class of organic oxidants. While the use of I(V) compounds Dess-Martin periodinane and IBX is widespread, this reagent class has long been plagued by issues of solubility and stability. Extensive effort has been made for derivatizing these scaffolds to modulate reactivity and physical properties but considerable room for innovation still exists. Herein, we describe the preparation, thermal stability, optimized geometries, and synthetic utility of an emerging class of I(V) reagents, Bi(N)-HVIs, possessing datively bound bidentate nitrogen ligands on the iodine center. Bi(N)-HVIs display favorable safety profiles, improved solubility, and comparable to superior oxidative reactivity relative to common I(V) reagents. The highly modular synthesis and in situ generation of Bi(N)-HVIs provides a novel and convenient screening platform for I(V) reagent and reaction development.
- Xiao, Xiao,Roth, Jessica M.,Greenwood, Nathaniel S.,Velopolcek, Maria K.,Aguirre, Jordan,Jalali, Mona,Ariafard, Alireza,Wengryniuk, Sarah E.
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p. 6566 - 6576
(2021/05/06)
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- Cycloaddition of carbon dioxide to epoxides by highly active constrained aluminum chloride complexes
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The transformation of carbon dioxide (CO2) and epoxides to cyclic carbonates has gained much interest due to its low cost, abundance, low toxicity, and renewability. Therefore, novel constrained aluminum chloride complexes were developed based on bis(salicylimine) ligands for epoxides/CO2 coupling reactions. The five-membered rings attached to the aromatic rings were designed to enlarge the coordination pocket around the aluminum center as demonstrated by single-crystal X-ray crystallography. Addition of propylene oxide (PO) to a mixture of an aluminum chloride complex and tetrabutylammonium bromide (TBAB) rapidly gave (ligand)Al-OCH(Me)CH2Cl and (ligand)Al-OCH(Me)CH2Br in similar quantities. The anion exchange between (ligand)Al-Cl and TBAB was found to be faster than the ring-opening of PO. From a series of catalyst screening and optimization, the combination of catalyst 2g having no substituent on the aromatic rings and TBAB displayed very high activity (TOF up to 10?800 h-1) for the PO/CO2 coupling reaction. This catalyst system was extended to eleven more examples of epoxides. Moreover, excellent selectivity for cyclic carbonate production was observed for both terminal and internal epoxides.
- Laiwattanapaisarn, Nattiya,Phomphrai, Khamphee,Virachotikul, Arnut
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p. 11039 - 11048
(2021/08/24)
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- g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
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g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
- Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
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p. 2292 - 2298
(2021/04/12)
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- Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
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Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
- Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
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p. 5077 - 5085
(2021/08/16)
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- Homobenzylic Oxygenation Enabled by Dual Organic Photoredox and Cobalt Catalysis
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Activation of aliphatic C(sp3)-H bonds in the presence of more activated benzylic C(sp3)-H bonds is often a nontrivial, if not impossible task. Herein we show that leveraging the reactivity of benzylic C(sp3)-H bonds to achieve reactivity at the homobenzylic position can be accomplished using dual organic photoredox/cobalt catalysis. Through a two-part catalytic system, alkyl arenes undergo dehydrogenation followed by an anti-Markovnikov Wacker-type oxidation to grant benzyl ketone products. This formal homobenzylic oxidation is accomplished with high atom economy without the use of directing groups, achieving valuable reactivity that traditionally would require multiple chemical transformations.
- McManus, Joshua B.,Griffin, Jeremy D.,White, Alexander R.,Nicewicz, David A.
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supporting information
p. 10325 - 10330
(2020/07/27)
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- Negative allosteric modulators of the GluN2B NMDA receptor with phenylethylamine structure embedded in ring-expanded and ring-contracted scaffolds
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A set of GluN2B NMDA receptor antagonists with conformationally restricted phenylethylamine substructure was prepared and pharmacologically evaluated. The phenylethylamine substructure was embedded in ring expanded 3-benzazocines 4 as well as ring-contracted tetralinamines 6 and indanamines 7. The ligands 4, 6 and 7 were synthesized by reductive alkylation of secondary amine 11, reductive amination of ketones 12 and 16 and nucleophilic substitution of nosylates 14 and 17. The moderate GluN2B affinity of 3-benzazocine 4d (Ki = 32 nM) translated into moderate cytoprotective activity (IC50 = 890 nM) and moderate ion channel inhibition (60% at 10 μM) in two-electrode voltage clamp experiments with GluN1a/GluN2B expressing oocytes. Although some of the tetralinamines 6 and indanamines 7 showed very high GluN2B affinity (e.g. Ki (7f) = 3.2 nM), they could not inhibit glutamate/glycine inducted cytotoxicity. The low cytoprotective activity of 3-benzazocines 4, tetralinamines 6 and indanamines 7 was attributed to the missing OH moiety at the benzene ring and/or in benzylic position. Docking studies showed that the novel GluN2B ligands adopt similar binding poses as Ro 25–6981 with the central H-bond interaction between the protonated amino moiety of the ligands and the carbamoyl moiety of Gln110. However, due to the lack of a second H-bond forming group, the ligands can adopt two binding poses within the ifenprodil binding pocket.
- Bechthold, Elena,Gawaskar, Sandeep,Robaa, Dina,Schepmann, Dirk,Schreiber, Julian A.,Seebohm, Guiscard,Sippl, Wolfgang,Temme, Louisa,Wünsch, Bernhard
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supporting information
(2020/02/18)
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- Synthesis method of 2-indanone
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The invention discloses a synthesis method of 2-indanone. Glacial acetic acid, hydrogen peroxide, acetic anhydride, indene and ethyl orthosilicate are used as major raw materials. The synthesis process has the advantages that under the effect of a loaded AlCl3/SBA-15 catalyst, 1,2-indene diol generated by oxidation reaction of the acetic anhydride and the indene is subjected to sulfuric acid acidification; sublimation purification is performed to obtain a high-purity 2-indanone intermediate. In the preparation process, no waste liquid or waste gas is generated; steamed acetic acid can be continuously brought into operation; the product yield is improved; meanwhile, the green production environment-protection requirements are achieved.
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Paragraph 0008-0029
(2019/02/06)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Wolff Rearrangement of Oxidatively Generated α-Oxo Gold Carbenes: An Effective Approach to Silylketenes
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Gold-catalyzed oxidations of alkynes by N-oxides offer direct access to reactive α-oxo gold carbene intermediates from benign and readily available alkynes instead of hazardous diazo carbonyl compounds. Despite various versatile synthetic methods developed based on this strategy, one of the hallmarks of α-oxo carbene/carbenoid chemistry, that is, the Wolff rearrangement, has not been realized in this context. This study discloses the first examples that show the Wolff rearrangement can be readily realized by α-oxo gold carbenes oxidatively generated from TBS-terminated alkynes (TBS=tert-butyldimethylsilyl). The thus-generated silylketenes can be either isolated pure or subsequently trapped by various internal or external nucleophiles in one pot to afford α-silylated carboxylic acids, their derivatives, or TBS-substituted allenes.
- Zheng, Yang,Zhang, Junqi,Cheng, Xinpeng,Xu, Xinfang,Zhang, Liming
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p. 5241 - 5245
(2019/04/04)
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- Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
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An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
- Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 725 - 738
(2018/10/20)
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- Sulfur and nitrogen-doped porous cobalt carbon catalyst for high efficient aerobic oxidation of hydrocarbons
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The selective oxidation of hydrocarbons to corresponding ketones under green reaction conditions is of more and more important in chemical processes due to environmental and economic pressure. In this respect, we successfully prepared high efficient sulfur and nitrogen-doped porous cobalt carbon catalyst through a simple but efficient one-pot method. Potassium thiocyanate (KSCN) is using as sulfur source and complexing agent, what's more, KSCN also acts as pore-forming agent to create larger specific surface area. In addition, the as-obtained catalyst shows high catalytic performance for oxidation of hydrocarbons under solvent-free and oxygen as oxidant conditions, especially for ethylbenzene, the conversion is up to 82% with 88% of selectivity for acetophenone, which is an exciting result due to the relative low activity of oxygen in comparison with tert-butyl hydroperoxide as oxidant. This is due to structure defect and Co4S3 by the doping of KSCN in CoNC catalysts, which may result in the improvement of the catalytic performance of the catalysts.
- Lin, Xiu,Jie, Shanshan,Liu, Zhigang
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p. 143 - 149
(2018/06/18)
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- Cobalt/N-Hydroxyphthalimide(NHPI)-Catalyzed Aerobic Oxidation of Hydrocarbons with Ionic Liquid Additive
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A highly efficient and solvent-free system of cobalt/NHPI-catalyzed aerobic oxidation of hydrocarbons was developed using imidazolium-based ionic liquid (IL) as an additive. These amphipathic ILs were found self-assemble at the interface between the organic hydrocarbons and the aqueous phase of catalyst combination (Co/NHPI), with forming a solution of reversed multilamellar vesicles for catalysis. The initial reaction rate was influenced by both the composition of microdomains and the structure of IL launched. Consequently, a proper water content (χH2O) of wet IL was requisite to reach the optimum reactivity. Besides, the interfacial boundary between aqueous and organic phase composed by C2-alkylated imidazolium ILs, such as [bdmim]SbF6 and [C12dmim]SbF6, not only has ternary aggregates (hydrocarbons/IL/H2O) of higher stability but renders O2 a faster diffusion rate and higher concentration, thereby offering a high reactivity of the protocol towards hydrocarbon oxidation.
- Mahmood, Sajid,Xu, Bao-Hua,Ren, Tian-Lu,Zhang, Zhi-Bo,Liu, Xiao-Min,Zhang, Suo-Jiang
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- N-Hydroxyphthalimide Anchored on Diamond Nanoparticles as a Selective Heterogeneous Metal-free Oxidation Catalyst of Benzylic Hydrocarbons and Cyclic Alkenes by Molecular O2
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N-hydroxyphthalimide (NHPI) derived from trimellitic anhydride has been covalently anchored (4 wt %) through ester bonds to the surface of commercial diamond nanoparticles previously functionalized by chemical and thermal treatments (DH). IR spectroscopy of the NHPI/DH solid shows the presence of a characteristic peak at 1735 cm?1 attributable to the ester bond, while solid-state MAS 13C NMR spectroscopy shows two broad bands corresponding to carbon atoms of carbonyl groups (167 ppm) and aromatic carbons (127 ppm). NHPI/DH promotes autoxidation of isobutylbenzene involving superoxide (O2 .?) and hydroperoxide (HOO?) radicals; NHPI/DH can be reused at least three times and reach a minimum turnover number as high as 20 600, which is probably due to the inertness of the diamond surface, allowing free diffusion of reactive oxygen species. Analogous materials in which NHPI was anchored on activated carbon and multiwall carbon nanotubes were inefficient as autoxidation catalysts. NHPI/DH is able to promote also selective aerobic oxidation of other benzylic hydrocarbons and cycloalkenes.
- Blandez, Juan F.,Navalón, Sergio,álvaro, Mercedes,García, Hermenegildo
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p. 198 - 205
(2017/09/13)
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- Multipotent AChE and BACE-1 inhibitors for the treatment of Alzheimer's disease: Design, synthesis and bio-analysis of 7-amino-1,4-dihydro-2H-isoquilin-3-one derivates
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In this paper, the preparation of a new class of multi-target-directed ligands (MTDLs) based on a 7-amino-1,4-dihydro-2H-isoquilin-3-one, whose lead (compound I) showed promising properties in acetylcholinesterase (AChE) inhibitory activity [1], is described. The results of in vitro activities and molecular docking demonstrated that the target molecule (compounds 10a-n) with three parts of aromatic moieties and appropriate structural length can interact with aromatic residues in catalytic active site (CAS), peripheral anionic site (PAS) and the channel of AChE. And the introduce of connecting amide bonds, enables the target molecules provide sufficient hydrogen bond donors and acceptors to interact with the catalytic site of BACE-1. Notably, compound 10d exerted excellent AChE inhibition (IC50 = 18.93 ± 1.02 pM, 181-fold more inhibitory effect compared with donepezil), BACE-1 inhibition (97.68 ± 8.01% at 20 μM), and good metal chelating property, which can be chosen as lead compound for further optimization of novel small ligand for the treatment of Alzheimer's disease.
- Zhao, Xiong-jie,Gong, Da-min,Jiang, Yu-ren,Guo, Dong,Zhu, Yao,Deng, You-chao
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p. 738 - 747
(2017/07/22)
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- Acceptorless Dehydrogenation of Alcohols Catalyzed by CuI N-Heterocycle Thiolate Complexes
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CuI N-heterocycle thiolate clusters efficiently catalyze the acceptorless dehydrogenation of alcohols at 70 °C. A variety of secondary/primary benzylic, allylic, and aliphatic alcohols are dehydrogenated to the corresponding ketones and aldehydes in high yields of isolated product upon release of H2. This simple catalytic system is involved in the synthesis of imines through the one-pot reaction of alcohols and amines.
- Tan, Da-Wei,Li, Hong-Xi,Zhang, Meng-Juan,Yao, Jian-Lin,Lang, Jian-Ping
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p. 1113 - 1118
(2017/03/27)
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- Cuprous compound based on nitrogen heterocyclic thiol ligand and preparation method and application of cuprous compound
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The invention discloses a cuprous compound based on a nitrogen heterocyclic thiol ligand and a preparation method and application of the cuprous compound. The cuprous compound based on the nitrogen heterocyclic thiol ligand is shown as a chemical formula [Cu6(pyt)6], wherein pyt refers to a negative ion formed by proton loss of sulfydryl in 2-mercaptopyridine. The cuprous compound based on the nitrogen heterocyclic thiol ligand is capable of catalyzing conversion of alcohol compounds into aldehyde compounds and ketone compounds, and has the advantages of high conversion efficiency, wide applicable range, mild reaction conditions and the like.
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Paragraph 0043
(2017/05/13)
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- Ionic Pathways in the Photochemistry of Cyclic Sulfite Esters
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The photochemistry of cyclic carbonate esters proceeds by the photochemical extrusion of carbon dioxide to give 1, 3-diradicals which produce oxiranes as well as other radical derived species. The corresponding cyclic sulfite esters, upon irradiation, give intermediates that are trapped by alcohols yet generate no oxiranes. These results are consistent with ionic intermediates.
- White, Rick C.,Arney Jr, Benny E.,Perry, Jacob,Thompson, Nathan,Pithan, Phil M.,von Gradowski, Sebastian,Ihmels, Heiko
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p. 1656 - 1659
(2017/03/27)
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- Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
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Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
- Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 12037 - 12040
(2016/09/28)
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- 7-amino-1,4-dihydroisoquinoline-3(2H)-one derivative, synthetic method and application thereof
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A 7-amino-1,4-dihydroisoquinoline-3(2H)-one derivative, a synthetic method and an application thereof. The invention belongs to the technical field of medicines and relates to the 7-amino-1,4-dihydroisoquinoline-3(2H)-one compound, the synthetic method, and the application thereof in medicine The compound is represented as the general formula (I), wherein X is (CH2)CO, n = 1-10; or is NH(CH2)CO, n = 2-10; or is NHCO(CH2)CO, n = 3-10; Y is CO(CH2), n = 1-10; or is CO(CH2)NH, n = 2-10; or is CO(CH2)CONH, n = 3-10, wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 refers to different substituent groups. The invention also discloses the structures and synthetic methods of these compounds and in-vitro acetylcholin esterase inhibition activity of the compounds. The compounds can be further developed into a novel drug for treating Alzheimer's disease.
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Paragraph 0028; 0030; 0031
(2016/10/08)
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- Oxidation of olefins using atmospheric oxygen atoms initiated by tert -butylhydroperoxide or hydrogen peroxide with silver nanoparticles deposited on MCM-41 as catalysts
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Silver nanosized particles were grown on the surface and in the channels of mesoporous silica (MCM-41) by stirring a mixture of AgNO3 and polyvinylpyrrolidone (PVP) in ethylene glycol in a 1:20 weight ratio with MCM-41 for 1 h. The heterogeneous product was analysed by BET surface area and X-ray powder diffraction measurements, as well as TEM images which indicated that 5 to 20 nm sized Ag particles were on the surface of MCM-41. The dried material, suspended in a mixture of 1,2-dichloroethane and acetonitrile and in the presence of tBuOOH held at 80 °C for 24 h, was capable of the oxidation of the olefins (Z)-cyclooctene, cyclohexene, styrene and indene resulting in a variety of oxidized products. Comparable oxidation was also accomplished in a green solvent mixture consisting of 3% NaCl dissolved in H2O and tBuOH (1:1 by volume). The catalyst was active for five sequential cycles. After the first cycle, H2O2 instead of tBuOOH could be used as the radical initiator as the Ag nanoparticles were passivated by the formation of AgCl on the surface. This research illustrates a method of oxygen activation allowing for the transfer of an oxygen atom from the atmosphere onto an olefin, presumably via the formation of a peroxide radical.
- Chen, Zhichao,Luck, Rudy L.
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p. 3354 - 3359
(2016/06/13)
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- Copper(II) and cobalt(II) tetrazole-saccharinate complexes as effective catalysts for oxidation of secondary alcohols
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Mononuclear Cu(II) and Co(II) complexes comprising 2-methyltetrazole-saccharinate bidentate N,N-chelating ligand have been synthesized for the first time and tested as homogeneous catalysts for oxidation of secondary alcohols in a solvent-free and microwave assisted protocol using aqueous tert-butyl hydroperoxide (TBHP) as oxidant. The developed catalytic system exhibits broad functional group compatibility, allowing efficient and selective conversion of a variety of secondary alcohols, including allylic ones, into the corresponding ketones. With typical 0.2 mol% content of the catalyst and under 20–50 W microwave irradiation, most reactions are complete within 10 min, presenting TONs up to 5.5 × 102 and TOFs up to 1.1 × 104 h?1. No additives and co-oxidants have been used, while TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl) acts as inhibitor in most cases. A plausible reaction mechanism involving the new catalytic systems is outlined.
- Frija, Luís M.T.,Alegria, Elisabete C.B.A.,Sutradhar, Manas,Cristiano, M. Lurdes S.,Ismael, Amin,Kopylovich, Maximilian N.,Pombeiro, Armando J.L.
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p. 283 - 290
(2016/11/04)
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- Oxone-acetone mediated Wacker-type oxidation of benzo-fused olefins
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Herein we disclose a novel application of the oxone-acetone combination for the Wacker-type oxidation of indenes and dihydronaphthalenes leading, respectively, to indan-2-ones and 2-tetralones. The amount of the base employed in the reaction seems to switch the reaction path from dioxygenation to Wacker-type oxidation. Control experiments suggest that the reaction is not proceeding via the epoxide route and also that there is no role of trace amounts of metals present in the reagents on the current oxidation.
- Phatake, Ravindra S.,Ramana, Chepuri V.
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supporting information
p. 3868 - 3871
(2015/06/08)
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- V-doped titanium mixed oxides as efficient catalysts for oxidation of alcohols and olefins
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V/TiO2 nanoparticles were synthesized by a one-pot solution combustion method using ammonium metavanadate and titanyl nitrate as a source of vanadium and titanium, respectively. Atomic absorption spectroscopy (AAS), FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the physicochemical properties of this compound. This compound shows efficient catalytic reactivity for epoxidation of olefins and oxidation of alcohols in the presence of H2O2 as an oxidant.
- Amini, Mojtaba,Naslhajian, Hadi,Farnia, S. Morteza F.
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p. 1581 - 1586
(2014/05/06)
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- OXONE-ACETONE MEDIATED METAL FREE PREPARATION OF SYN-DIOLS
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The present invention disclose a simple and high yielding process of Oxone-acetone mediated metal free syn-dihydroxylation of benzo fused olefins of formula (II) to obtain library of dioxolo compounds of formula (I). The invention further disclsoe a simple and high yielding process of Oxone-acetone mediated metal free syn-dihydroxylation of stilbene and its derivatives of formula (III) thereof. Also disclosed herein is Wacker-type oxidation of benzo-fused olefins of formula (X). The invention further disclose compounds of formula (I) which can be useful for the treatment of HIV, cancer or malaria.
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Page/Page column 30; 40
(2015/01/16)
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- Ruthenium(IV) porphyrin catalyzed highly selective oxidation of internal alkenes into ketones with Cl2pyNO as terminal oxidant
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A new method for the conversion of internal alkenes into ketones without cleavage of CC bond by using dichlororuthenium(IV) meso-tetrakis(2,6- dichlorophenyl)porphyrin [RuIV(TDCPP)Cl2] as catalyst and 2,6-dichloropyridine N-oxide(Cl2pyNO) as oxidant is developed.
- Wang, Zhi-Ming,Sang, Xue-Ling,Che, Chi-Ming,Chen, Jian
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supporting information
p. 1736 - 1739
(2014/03/21)
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- Transfer of 1-alkenyl groups between secondary amines. Relative stability and reactivity of enamines from popular organocatalysts
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Enamines from 3-methylbutanal and several Pro- and Phe-derived secondary amines were prepared in DMSO-d6, CD3CN, and CDCl 3. For the first time, the relative thermodynamic stabilities of these and other enamines were compared, and rapid exchanges of 1-alkenyl groups were demonstrated. Competition experiments showed that the most favored enamines (without significant steric inhibition of resonance) react more rapidly with electrophiles.
- Carneros, Hector,Sanchez, Dani,Vilarrasa, Jaume
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p. 2900 - 2903
(2014/06/23)
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- Thermochemistry and photochemistry of spiroketals derived from indan-2-one: Stepwise processes versus coarctate fragmentations
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Coarctate reactions are defined as reactions that include atoms at which two bonds are made and two bonds are broken simultaneously. In the pursuit of the discovery of new coarctate reactions we investigate the fragmentation reactions of cyclic ketals. Three ketals with different ring sizes derived from indan-2-one were decomposed by photolysis and pyrolysis. Particularly clean is the photolysis of the indan-2-one ketal 1, which gives o-quinodimethane, carbon dioxide and ethylene. The mechanism formally corresponds to a photochemically allowed coarctate fragmentation. Pyrolysis of the five-ring ketal yields a number of products. This is in agreement with the fact that coarctate fragmentation observed upon irradiation would be thermochemically forbidden, although this exclusion principle does not hold for chelotropic reactions. In contrast, fragmentation of the seven-ring ketal 3 is thermochemically allowed and photochemically forbidden. Upon pyrolysis of 3 several products were isolated that could be explained by a coarctate fragmentation. However, the reaction is less clean and stepwise mechanisms may compete.
- Bucher, Goetz,Heitmann, Gernot,Herges, Rainer
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p. 1668 - 1676
(2013/10/22)
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- Biarylphosphonite gold(I) complexes as superior catalysts for oxidative cyclization of propynyl arenes into indan-2-ones
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Striking gold: A series of variously functionalized propynyl arenes was smoothly converted into indan-2-ones by a new gold(I)-catalyzed oxidative cyclization process. [LAu]NTf2 (Tf=trifluoromethanesulfonyl) is a superior catalyst both in terms of yield and kinetics for the present transformation. Copyright
- Henrion, Guilhem,Chavas, Thomas E. J.,Le Goff, Xavier,Gagosz, Fabien
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supporting information
p. 6277 - 6282
(2013/07/11)
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- Cyclic seleninate esters as catalysts for the oxidation of sulfides to sulfoxides, epoxidation of alkenes, and conversion of enamines to α-hydroxyketones
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Cyclic seleninate esters serve as catalysts for the rapid oxidation of sulfides to sulfoxides, alkenes to epoxides, and enamines to α-hydroxyketones. Optimal conditions were found that minimize the overoxidation of the product sulfoxides to sulfones and the hydrolysis of epoxides to diols. In some examples such as styrene derivatives, oxidative cleavage was observed instead of epoxidation. The enamine oxidations proceed via the initial formation of dimeric 2,5-diamino-1,4-dioxane species, which were hydrolyzed in situ to the final products. The structure of one such dimer was confirmed by X-ray crystallography.
- Mercier, Eric A.,Smith, Chris D.,Parvez, Masood,Back, Thomas G.
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experimental part
p. 3508 - 3517
(2012/06/04)
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- Phenyl substituted indenylphosphine ruthenium complexes as catalysts for dehydrogenation of alcohols
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Thermal treatment of (1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (1) and (3-mesityl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (3) with tBuONa followed by [(η6-cymene) RuCl2)]2 in methanol gave the adduct {(η6- cymene)RuCl2[(1H-inden-3-yl)PCy2]} (6) and {(η6-cymene)RuCl2[(3-mesityl-1H-inden-3-yl)PCy 2]} (7), respectively. Thermal treatment of (2-phenyl-1H-inden-3-yl) dicyclohexylphosphinium tetrafluoroborate (4) with tBuONa followed by [(η6-cymene)RuCl2)]2 or RuCl 3·3H2O in methanol gave {Ru[κ(P): (η6-2-phenyl-1H-inden-3-yl)PCy2]Cl2} (8). Whereas (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (5) reacted with [(η6-cymene)RuCl2)]2 (in toluene) or RuCl3·3H2O (in ethanol) to afford {Ru[κ(P):(η6-2-mesityl-1H-inden-3-yl)PCy 2]Cl2} (9). The molecular structures of complexes 6, 8 and 9 have been determined by single-crystal X-ray diffraction analysis. In addition, complexes 8 and 9 have been found to catalyze the acceptorless dehydrogenation of alcohols in toluene. 9 displayed high activity and different substrates, including cyclic and linear alcohols, were efficiently oxidized to ketones by using 2.0 mol% of catalyst.
- Yuan, Jia,Sun, Yue,Yu, Guang-Ao,Zhao, Cui,She, Neng-Fang,Mao, Shu-Lan,Huang, Peng-Shou,Han, Zhi-Jun,Yin, Jun,Liu, Sheng-Hua
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p. 10309 - 10316
(2013/01/14)
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- Efficient biocatalysis for the production of enantiopure (S)-epoxides using a styrene monooxygenase (SMO) and Leifsonia alcohol dehydrogenase (LSADH) system
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Herein we report the production of enantiopure epoxides through biocatalysis using recombinant Escherichia coli cells expressing Rhodococcus sp. ST-10 styrene monooxygenase (SMO) and Leifsonia sp. S749 alcohol dehydrogenase (LSADH) genes are described. Rhodococcus sp. ST-10 SMO catalyzed the epoxidation of various alkenes, including styrene derivatives, vinyl pyridines, and linear alkenes, to give (S)-epoxides. NADH was regenerated by the reduction of NAD + by LSADH with 2-propanol. The E. coli biocatalyst was used in an aqueous/organic biphasic reaction system and the reaction conditions were optimized. Under the optimized conditions, 170 mM of (S)-styrene oxide was obtained from styrene in the organic phase with excellent enantiomeric excess (99.8%). This biocatalytic process was used to synthesize various (S)-epoxides.
- Toda, Hiroshi,Imae, Ryouta,Itoh, Nobuya
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p. 1542 - 1549
(2013/02/21)
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- Relative tendency of carbonyl compounds to form enamines
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Equilibria between carbonyl compounds and their enamines (from O-TBDPS-derived prolinol) have been examined by NMR spectroscopy in DMSO-d 6. By comparing the exchange reactions between pairs (enamine A + carbonyl B → carbonyl A + enamine B), a quite general scale of the tendency of carbonyl groups to form enamines has been established. Aldehydes quickly give enamines that are relatively more stable than those of ketones, but there are exceptions to this expected rule; for example, 1,3-dihydroxyacetone acetals or 3,5-dioxacyclohexanones (2-phenyl-1,3-dioxan-5-one and 2,2-dimethyl-1,3- dioxan-5-one) show a greater tendency to afford enamines than many α-substituted aldehydes.
- Sanchez, Dani,Bastida, David,Bures, Jordi,Isart, Carles,Pineda, Oriol,Vilarrasa, Jaume
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supporting information; experimental part
p. 536 - 539
(2012/03/26)
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- Formation of five- and seven-membered rings enabled by the triisopropylsilyl auxiliary group
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A highly convenient synthetic pathway to 2-indanones from aldehydes was established. The introduction of a triisopropylsilyl group greatly facilitated Meinwald rearrangement of the intermediate epoxides and alleviated the necessity of polysubstitution for the clean formation of indenes and cyclopentadienes via cyclodehydration of allylic alcohols; unprecedented freedom with respect to the product structure was thus achieved. The developed methodology could also be applicable to the formation of seven-membered rings leading to dibenzo[7]annulenes and dibenzosuberones.
- Usanov, Dmitry L.,Yamamoto, Hisashi
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supporting information; experimental part
p. 414 - 417
(2012/02/15)
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- Gold(I)-catalyzed cyclodehydration enabled by the triisopropylsilyl group: A synthetically versatile methodology
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Introduction of a triisopropylsilyl group into allyl and allenyl carbinols greatly enhances the efficiency of gold(I)-catalyzed cyclodehydration, which can provide rapid access to a library of various compounds including 1H-indenes (Table 2 and Scheme 5), benzofulvenes (Table 3), indan-2-ones (Scheme 2), fulvenes (Table 4), cyclopentadienes (Table 4), 5H-dibenzo[a,c][7]annulenes (Scheme 6) and dibenzosuberones (Scheme 6). The developed method enables unprecedented product generality for several classes of cyclodehydration reactions, which is particularly notable for the preparation of 1H-indenes. The first synthesis of non-benzo-fused fulvenes via cyclodehydration of allenyl vinyl carbinols could be accomplished. The protocol is remarkable for mild conditions, operational convenience, and easy access to starting materials. Copyright
- Usanov, Dmitry L.,Naodovic, Marina,Brasholz, Malte,Yamamoto, Hisashi
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p. 1773 - 1789,17
(2012/12/12)
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- Gold(III) complexes catalyze deoximations/transoximations at neutral pH
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Golden solution: A neutral solution of AuBr3, containing [AuBr2(OH)2]- in equilibrium with [AuBr 3(OH)]- and [AuBr4]-, promotes the chemoselective hydrolysis of robust oximes into carbonyl compounds without racemization (see scheme). The food additive diacetyl acts as a NH 2OH-trapping agent, thus avoiding the formation of gold nanoparticles and allows the reaction to run catalytically. Copyright
- Isart, Carles,Bastida, David,Bures, Jordi,Vilarrasa, Jaume
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experimental part
p. 3275 - 3279
(2011/05/12)
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- Synthesis of poly(indene carbonate) from indene oxide and carbon dioxide - A polycarbonate with a rigid backbone
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The catalytic coupling of carbon dioxide with indene oxide utilizing (salen)Co(III)-2,4-dinitrophenoxide in the presence of an onium salt is presented. X-ray structural data for indene oxide monomer as well as cisindene carbonate display near planarity of the fused cyclopentene and benzene rings. Low temperature (0 °C) is required to selectively afford copolymer vs cyclic carbonate from the coupling reactions of CO2 and indene oxide. The produced poly(indene carbonate) samples have molecular weights of up to 7100 Da, with corresponding glass transition temperatures of up to 134 °C, the highest yet reported for polycarbonates produced from CO2/epoxides coupling. Poly(indene carbonate) is thermally stable up to 249 °C. The polymerizations are well controlled, with PDI values ≤1.3.
- Darensbourg, Donald J.,Wilson, Stephanie J.
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supporting information; experimental part
p. 18610 - 18613
(2012/01/31)
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- Novel polyaniline supported cobalt catalyzed aerobic oxidation of unsaturated organic compounds
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The oxidation of organic compounds with carbon-carbon double bond with molecular oxygen under atmospheric pressure in the presence of new polyaniline supported catalyst 1 has been studied. This catalyst turned out to be efficient and selective for oxidation of some unsaturated organic compounds. Oxidation of alkenes, cycloalkenes and terpenes give corresponding epoxy derivatives, whereas organic compounds with carbon carbon double bond in benzylic position give ketones as a main product. Taylor & Francis Group, LLC.
- Pielichowski, Jan,Kowalski, Grzegorz
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experimental part
p. 105 - 111
(2011/08/03)
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- New catalysts based on poly(aspartic acid) for oxidation reaction
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In the current work we describe synthesis of novel poly(D, L-aspartic acid) catalysts for oxidation reactions. The catalysts were prepared by a three-step reaction procedure. First, poly(D, L-aspartic acid) (PAA) was synthesized by polycondensation reaction D, L-aspartic acid with propylene carbonate under microwave irradiation. In the second stage, poly(aspartic acid) sodium salt (PAA-Na) was obtained during the reaction of hydrolysis of cyclic forms of PAA in water solutions of sodium. The last stage of catalysts synthesis were reaction of poly(aspartic acid) sodium salt with cobalt or copper acetate. FTIR, 1H NMR, SEM, SEM-EDS, and SIMS were employed for characterization of the obtained catalysts were employed for characterization of the obtained catalysts. Oxidation reactions of some compounds were carried out on synthesized catalysts at atmospheric pressure in the presence of molecular oxygen. As the main products epoxides and ketone were obtained with very high yield and selectivity. Taylor & Francis Group, LLC.
- Hebda,Orlicki,Pielichowski
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scheme or table
p. 75 - 81
(2011/08/03)
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- New poly(organophosphazene) - Supported cobalt or copper (II) catalysts for the oxidation of alkenes
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Polymer-supported heterogeneous catalysts in form of complexes of poly[bis(pyridine-2-oxy)phosphazene] with cobalt(II) or copper(II) acetate were synthesized. The catalysts were prepared by a three-step reaction procedure. First, poly(dichlorophosphazene) was synthesized by thermal polymerization of cyclic trimer of hexachlorocyclotriphosphazene. In the second stage, the poly(dichlorophosphazene) structure was converted into the 2-hydroxypyridine by a nucleophilic substitution reaction. The last stage of the catalyst synthesis was the reaction of poly[bis(pyridine-2-oxy)phosphazene] with cobalt acetate or copper acetate. FTIR, 31P NMR, AAS, BET, SEM, SEM-EDS and TG were employed for characterization of the obtained catalysts. The complexes were applied as heterogeneous catalysts in oxidation of dodecene, indene, limonene in the presence of molecular oxygen in acetonitrile (as solvent) at 60C, using isobutyraldehyde as an oxygen transfer agent. Oxidation reactions of aliphatic and aromatic hydrocarbons let to formation of epoxides or ketones with good yield and high selectivity.
- Blaz,Pielichowski
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experimental part
p. 345/[711]-355/[721]
(2009/10/11)
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- Organocatalytic asymmetric conjugate addition to allenic esters and ketones
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The first example of an organocatalytic enantioselective conjugate addition of cyclic β-ketoesters and glycine imine derivatives to electron-deficient allenes is described. We disclose that the corresponding chiral β,γ-unsaturated carbonyl compounds are formed exclusively under phase-transfer conditions using either cinchona-alkaloid-derived or biphenyl-based chiral quaternary ammonium salts as catalysts. The scope of the reaction for β-ketoesters is outlined for allenes having a ketone or ester motif as electron-withdrawing group as well as different substituents in the 3-position, giving the optically active products in high yields and excellent diastereo- and enantioselectivities (90-96% ee). The conjugate addition also proceeds for a number of cyclic β-ketoesters having different ring sizes, ring systems, and substituents in high yields and enantioselectivities. Glycine imine derivatives also undergo the asymmetric conjugate addition to electron-deficient allenes in high yields and with enantioselectivities in the range of 60-88% ee, thus providing a rapid entry to optically active α-vinyl-substituted α-amino acid derivatives. It is shown that the enantioselectivity is strongly dependent on the size of the ester moiety of the nucleophile in combination with the catalytic system used. The high synthetic value of the chiral products arising from these new catalytic processes is demonstrated by two straightforward transformations leading in one case to optically active hexahydrobenzopyranones and in the other to substituted pyroglutamates (γ-lactames).
- Elsner, Petteri,Bernardi, Luca,Della Sala, Giorgio,Overgaard, Jacob,J?rgensen, Karl Anker
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p. 4897 - 4905
(2008/09/21)
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- Activation of DMSO by phosphonitrilic chloride: An efficient method for oxidation of alcohols
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A variety of alcohols have been oxidized under mild conditions by a dimethylsulfoxide (DMSO)-chlorophosphazene complex. Sensitive groups such as silyl and tetrahydropyranyl (THP) ethers are stable under this condition. Copyright Taylor & Francis Group, LLC.
- Pandey, Sanjay K.,Bisai, Alakesh,Singh, Vinod K.
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p. 4099 - 4103
(2008/03/13)
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- Daucus carota and baker's yeast mediated bio-reduction of prochiral ketones
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Stereoselective reduction of prochiral ketones to the corresponding alcohols using biocatalysts has attracted much attention, from the viewpoint of green chemistry. Asymmetric reduction of indanone, tetralone and hydroxyl trimonoterpene ketones to the corresponding enantiomerically pure (S)-alcohols, using Daucus carota plant homogenate and fermented baker's yeast cells, is described. The present study illustrates the broad substrate selectivity of the dehydrogenase enzymes present in the D. carota in the synthesis of a wide range of chiral secondary alcohols of biological importance.
- Yadav, Jhillu S.,Reddy, Garudammagari S.K.K.,Sabitha, Gowravaram,Krishna, Avvaru D.,Prasad, Attaluri R.,Hafeez-U-R-Rahaman,Vishwaswar Rao, Katta,Bhaskar Rao, Adari
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p. 717 - 723
(2008/02/02)
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- Substrate specificity and reaction mechanism of recombinant styrene oxide isomerase from Pseudomonas putida S12
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To clarify the substrate specificity of the recombinant styrene oxide isomerase, various epoxides were subjected to the reaction. From the substituent effect on the rate of isomerization, the mechanism of the isomerase catalyzed reaction was estimated.
- Miyamoto, Kenji,Okuro, Kou,Ohta, Hiromichi
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p. 3255 - 3257
(2008/02/02)
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- Studies of reactions of o-xylylene-α,α′-dihalides with palladium complexes and the catalytic synthesis of 3-isochromanone
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Homogeneous catalysis by palladium complexes with phosphorus(III) ligands of the carbonylation of o-xylylene dihalides in the presence of water to form 3-isochromanone has been studied. Triphenylphosphine was found to provide the most effective catalyst, and by-products and intermediates of systems containing this ligand have been investigated. 2-Indanone is one by-product but is unstable to decomposition under catalytic conditions. Excess PPh3 is necessary to prolong activity of the catalyst but is also transformed to bis-phosphonium compound [o-C6H4(CH2PPh3)2]X2 (X = Cl or Br); this quaternization has been investigated and the structure of the bromide salt determined by X-ray diffraction. An unstable oxidative addition product of Pd(PPh3)4 was detected as a probable intermediate and related to the previously reported but catalytically-inactive complex trans-Pd(o-CH2C6H4CH2Cl)Cl(PMe3)2, which has been structurally characterized by X-ray diffraction in this work.
- Jones, Ray V.H.,Lindsell, W. Edward,Paddon-Jones, Greg C.,Palmer, Daniel D.,Preston, Peter N.,Rosair, Georgina M.,Whitton, Alan J.
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p. 2378 - 2385
(2007/10/03)
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- Liquid phase oxidation of alkenes with nitrous oxide to carbonyl compounds
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A variety of substrates including linear, cyclic, heterocyclic alkenes and their derivatives were tested in the liquid phase non-catalytic oxidation with nitrous oxide (N2O). The structure and composition of the alkenes have a significant effect on the reaction selectivity. With many alkenes, N 2O oxidation provides a selective way for the preparation of carbonyl compounds. The generation of carbene (or diazomethane) species is a remarkable feature of the oxidation of terminal alkenes.
- Starokon,Dubkov,Babushkin,Parmon,Panov
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p. 268 - 274
(2007/10/03)
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- Bismuth compounds in organic synthesis. Deprotection of ketoximes using bismuth bromide-bismuth triflate
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Ketoximes undergo deprotection in CH3CN/acetone/H2O (3:6:1) in the presence of 20-40 mol percent BiBr3/5 mol percent Bi(OTf)3. Bismuth(III) salts are relatively non-toxic, insensitive to air and inexpensive. These features coupled with the use of a relatively non-toxic solvent system make this method an attractive alternative to existing routes for deprotection of ketoximes.
- Arnold, Joshua N.,Hayes, Patrick D.,Kohaus, Robert L.,Mohan, Ram S.
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p. 9173 - 9176
(2007/10/03)
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- Solvent-free oxidation of alcohols by t-butyl hydroperoxide catalyzed by water-soluble copper complex
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The catalytic system composed of CuCl2 and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC), was found to be highly efficient for the selective oxidation of secondary benzylic, allylic and propargylic alcohols to the corresponding ketones, with aqueous t-butyl hydroperoxide under phase-transfer catalysis conditions. The catalytic system is stable and can be recycled and reused several times without loss of activity.
- Ferguson, Gabriel,Ajjou, Abdelaziz Nait
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p. 9139 - 9142
(2007/10/03)
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- A new polyaniline-based catalyst for the oxidation of alkenes
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Polymer-supported heterogeneous catalysts based on cobalt acetate and Co(II)Salen were synthesized. As a support, conjugated polymers were used: polyaniline, poly-o-toluidine or poly-o-anisidine. Oxidation reactions of alkenes were carried out on synthesized polymer-supported catalysts at atmospheric pressure in the presence of molecular oxygen. Epoxides or ketones were obtained as main products. Oxidation reactions were carried out under very mild conditions, at room temperature, and the desired products were obtained in very high selectivity and relatively high yields.
- Kowalski, Grzegorz,Pielichowski, Jan
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p. 2107 - 2109
(2007/10/03)
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