- A pyridylsilyl group expands the scope of catalytic intermolecular Pauson-Khand reactions
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Now even unstrained alkenes can be used in catalytic intermolecular Pauson-Khand reactions [Eq. (a)]. This is made possible by the use of the directing group dimethyl(2-pyridyl)silyl, which can be easily removed at the end of the reaction. Furthermore, one observes completely regioselective incorporation of substituents at the 4- and 5-positions of the 2-cyclopentenone structure.
- Itami, Kenichiro,Mitsudo, Koichi,Yoshida, Jun-Ichi
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Read Online
- Synthesis of Cyclopentenones through Rhodium-Catalyzed C-H Annulation of Acrylic Acids with Formaldehyde and Malonates
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An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones based on a three-component reaction of acrylic acids, formaldehyde, and malonates via vinylic C-H activation is reported. Exploratory studies showed that 5-alkylation of as-prepared cyclopentenones could be realized smoothly by the treatment of a variety of alkyl halides with a Na2CO3/MeOH solution. Excess formaldehyde and malonate led to a multicomponent reaction that afforded the multisubstituted cyclopentenones through a Michael addition.
- Yu, Shuling,Hong, Chao,Liu, Zhanxiang,Zhang, Yuhong
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supporting information
p. 5054 - 5059
(2021/07/20)
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- Aqueous chemoenzymatic one-pot enantioselective synthesis of tertiary α-aryl cycloketonesviaPd-catalyzed C-C formation and enzymatic C=C asymmetric hydrogenation
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An aqueous chemoenzymatic cascade reaction combining Pd-catalyzed C-C formation and enzymatic C=C asymmetric hydrogenation (AH) was developed for enantioselective synthesis of tertiary α-aryl cycloketones in good yields and excellent enantioselectivities. The stereopreference of the enzyme in AH of α-aryl cyclohexenones was studied. An enantiocomplementary enzyme was obtained by site-directed mutation.
- Luan, Pengqian,Liu, Yunting,Li, Yongxing,Chen, Ran,Huang, Chen,Gao, Jing,Hollmann, Frank,Jiang, Yanjun
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p. 1960 - 1964
(2021/03/26)
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- Synthesis of novel methyl jasmonate derivatives and evaluation of their biological activity in various cancer cell lines
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Warburg hypothesized that the energy consumption of cancer cells is different than the normal cells. When compared to normal conditions, cancer cells do not undergo tricarboxylic acid (TCA) cycle therefore resulting in more lactate in the cells. Glycolysis pathway is a way of cancer cells to provide energy. The first step in glycolysis is the phosphorylation of glucose to glucose-6-phosphate. This reaction is catalyzed by the hexokinase-II enzyme (HK-II) which is known to be overexpressed in tumor cells. The feeding of cancer cells can be prevented by inhibiting the hexokinase-II enzyme in the first step of aerobic glycolysis. In literature, Methyl Jasmonate (MJ) is known as a Hexokinase-II inhibitor since it disposes VDAC and HK-II interaction on mitochondrial membrane. In our study, we aimed to increase the activity by synthesizing the novel MJ analogues with appropriate modifications. Here we report Hexokinase-2 enzyme and cell viability study results in different cancer cells. Based on the three different cancer cell lines we investigated, our novel MJ analogues proved to be more potent than the original molecule. Thus this research may provide more efficacious/novel HK-II inhibitors and may shed light to develop new anti-cancer agents.
- Sucu, Bilgesu Onur,Ipek, Ozgecan Savlug,Kurtulus, Sukran Ozdatli,Yazici, Busra Emine,Karakas,Guzel, Mustafa
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- METHOD FOR SYNTHESIZING NOVEL COMPOUNDS DERIVED FROM 3-HYDROXY-CYCLOPENTYL ACETIC ACID
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The present invention relates to compounds of formula (I): in which R1 is a hydrogen atom, a phenyl radical, or a straight or branched, saturated or unsaturated hydrocarbon radical having 1 to 8 carbon atoms.
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Paragraph 0207; 0211; 0212; 0213
(2018/03/25)
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- Diastereoselective Synthesis of Planar Chiral Phosphoramidites with a Ferrocenophane Scaffold
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A new family of planar chiral phosphoramidites with a [3]ferrocenophane structure was synthesized. The synthetic strategy involved diastereoselective formation of the chiral ferrocene units from suitable substituted bis-cyclopentadienyl derivatives. Preliminary coordination studies of these ligands were undertaken with the synthesis of palladium and platinum complexes.
- Neel, Mathilde,Retailleau, Pascal,Voituriez, Arnaud,Marinetti, Angela
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p. 797 - 801
(2018/03/21)
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- Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems
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Developing norbornadiene-quadricyclane (NBD-QC) systems for molecular solar-thermal (MOST) energy storage is often a process of trial and error. By studying a series of norbornadienes (NBD-R2) doubly substituted at the C7-position with R = H, M
- Jorner, Kjell,Dreos, Ambra,Emanuelsson, Rikard,El Bakouri, Ouissam,Galván, Ignacio Fdez.,B?rjesson, Karl,Feixas, Ferran,Lindh, Roland,Zietz, Burkhard,Moth-Poulsen, Kasper,Ottosson, Henrik
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p. 12369 - 12378
(2017/07/10)
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- Unusual, selective, reductive, deoxygenation of cyclopentenone alcohols
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A selective, reductive, deoxygenation of 2-aryl-4-hydroxycyclopent-2-en-1-ones to afford 2-aryl-cyclopent-2-en-1-ones was achieved by NaBH4-CeCl3in methanol.
- Bavikar, Suhas R.,Lasonkar, Trupti P.,Chavan, Subhash P.,Borate, Hanumant B.
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supporting information
p. 5241 - 5243
(2015/01/09)
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- Versatile CuI/Pd0 dual catalysis for the synthesis of quaternary α-allylated carbonyl compounds: Development, mechanistic investigations and scope
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We report herein a versatile cooperative dual catalysis reaction based on a CuI/Pd0 system. Mechanistic investigation shows that every component plays a crucial role in determining the reaction outcome. The reaction is successfully extended to various substrates; such as α,β-unsaturated ketones, malonates and coumarins. The strategy tolerates different substitution patterns and affords good yields for each family of substrates.
- Nahra, Fady,Mace, Yohan,Boreux, Arnaud,Billard, Francois,Riant, Olivier
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p. 10970 - 10981
(2014/09/17)
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- Asymmetric hydrogenation of α,α′-disubstituted cycloketones through dynamic kinetic resolution: An efficient construction of chiral diols with three contiguous stereocenters
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Chiral diols with three contiguous stereocenters were synthesized by a highly enantioselective ruthenium-catalyzed asymmetric hydrogenation of racemic α,α′-disubstituted cycloketones involving dynamic kinetic resolution. This new catalytic asymmetric method provides a concise route to the alkaloid (+)-γ-lycorane. Copyright
- Liu, Chong,Xie, Jian-Hua,Li, Ya-Li,Chen, Ji-Qiang,Zhou, Qi-Lin
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supporting information
p. 593 - 596
(2013/02/23)
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- Oxidative conversion of silyl enol ethers to α,β-unsaturated ketones employing oxoammonium salts
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The oxidative conversion of silyl enol ethers to α,β-unsaturated ketones using a less-hindered class of oxoammonium salts (AZADO +BF4-) is described. The reaction proceeds via the ene-like addition of oxoammonium salts to silyl enol ethers.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 154 - 157
(2012/02/16)
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- CuCl-catalyzed reaction of zirconacyclopentenes with oxalyl chloride: a new pathway for the preparation of cyclopentenones
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Zirconacyclopentenes, which are easily prepared from alkynes and EtMgBr (or ethylene) and Cp2ZrCl2, reacted with oxalyl chloride in the presence of catalytic amount of CuCl to give cyclopentenones in high yields. The reaction was per
- Chen, Chao,Liu, Yundong,Xi, Chanjuan
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supporting information; experimental part
p. 5434 - 5436
(2009/12/06)
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- The palladium-catalyzed aerobic kinetic resolution of secondary alcohols: Reaction development, scope, and applications
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The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen as the stoichiometric oxidant. Mechanistic insights regarding the role of the base and hydrogen-bond donors have resulted in several improvements to the original system. Namely, addition of cesium carbonate and tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23°C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kinetic resolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good-toexcellent selectivity factors. This catalyst system has also been applied to the desymmetrization of meso-diols, providing high yields of enantioenriched hydroxyketones.
- Ebner, David C.,Bagdanoff, Jeffrey T.,Ferreira, Eric M.,McFadden, Ryan M.,Caspi, Daniel D.,Trend, Raissa M.,Stoltz, Brian M.
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supporting information; experimental part
p. 12978 - 12992
(2010/06/19)
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- A Pd(II)-catalyzed ring-expansion reaction of cyclic 2-azidoalcohol derivatives: Synthesis of azaheterocycles
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(Chemical Equation Presented) A Pd(II)-catalyzed ring expansion-reaction of cyclic 2-azidoalcohol derivatives was found to proceed via an unprecedented C-C bond cleavage-C-N bond formation sequence, providing substituted azaheterocycles.
- Chiba, Shunsuke,Xu, Yan-Jun,Wang, Yi-Feng
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supporting information; experimental part
p. 12886 - 12887
(2009/12/06)
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- Palladium-catalyzed enantioselective oxidation of chiral secondary alcohols: Access to both enantiomeric series
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(Chemical Equation Presented) Rapid resolution: A new catalyst system for the oxidative kinetic resolution of secondary alcohols leads to dramatic rate increases. This system allows the use of a diamine to provide access to either enantiomer of a range of alcohols with good selectivity factors (see scheme). This method has been applied to the formal total synthesis of (-)-amurensinine.
- Ebner, David C.,Trend, Raissa M.,Genet, Cedric,McGrath, Matthew J.,O'Brien, Peter,Stoltz, Brian M.
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scheme or table
p. 6367 - 6370
(2009/03/11)
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- The α-arylation of α-bromo- and α-chloroenones using palladium-catalysed cross-coupling
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The palladium-catalysed cross-coupling reaction of various arylboronic acids with α-bromoenones and α-chloroenones offers an operationally simple approach to the synthesis of both cyclic and acyclic α-arylenones.
- Banks, James C.,Mele, David Van,Frost, Christopher G.
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p. 2863 - 2866
(2007/10/03)
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- Practical and efficient Suzuki-Miyaura cross-coupling of 2-iodocycloenones with arylboronic acids catalyzed by recyclable Pd(0)/C
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The first Suzuki-Miyaura cross-coupling of 2-iodocycloenones with arylboronic acids catalyzed by 10% Pd(0)/C is described as an interesting alternative to classical homogeneous conditions. Most of the substrate reacted under mild condition at 25 °C under air in aqueous DME. The conditions described tolerate a wide range of iodoenones and boronic acids. Notably, the procedure features inexpensive reagents and solvents with low toxicity rendering the method environmentally benign. Additionally 10% Pd(0)/C could be recovered and efficiently reused at least five times without significant alteration of the yields of the cross-coupled product.
- Felpin, Francois-Xavier
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p. 8575 - 8578
(2007/10/03)
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- Cyclopropyl alkynes as mechanistic probes to distinguish between vinyl radical and ionic intermediates
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(Chemical Equation Presented) The reactions of (trans-2-phenylcyclopropyl) ethyne, 1a, (trans,trans-2-methoxy-3-phenylcyclopropyl)-ethyne, 1b, and (trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)ethyne, 1c, with either aqueous sulfuric acid or tris(trimethylsilyl)silane (or tributyltin hydride) and AIBN have been investigated. Protonation and addition of the silyl (or stannyl) radical occurred at the terminal position of the alkyne giving an α-cyclopropyl-substituted vinyl cation or radical, respectively. Under both reaction conditions, 1a yielded products derived from ring opening toward the phenyl substituent. Alkynes 1b and 1c, however, gave different products depending on whether radical or cationic conditions were used. When radical conditions were employed, products derived from regioselective ring opening toward the phenyl substituent were obtained. In contrast, when cationic conditions were employed, products derived from selective ring opening toward the methoxy substituent were isolated. The corresponding α-cyclopropyl- substituted vinyllithium derivatives were also synthesized and were found to be stable toward rearrangement. An estimate of the rate constants for ring opening of the α-cyclopropylvinyl cations was also made: values of 10 10-1012 s-1 were found for the vinyl cations derived from protonation of the terminal carbon of alkynes 1a-c. Based on these results, cyclopropyl alkynes 1a-c can be classified as hypersensitive mechanistic probes for the detection of vinyl radical or cationic intermediates generated adjacent to the cyclopropyl ring and, in the case of 1b and 1c, the distinction between a radical or cationic intermediate is possible.
- Gottschling, Stephen E.,Grant, Tina N.,Milnes, Kaarina K.,Jennings, Michael C.,Baines, Kim M.
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p. 2686 - 2695
(2007/10/03)
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- A Pauson-Khand-type reaction between alkynes and olefinic aldehydes catalyzed by rhodium/cobalt heterobimetallic nanoparticles: An olefinic aldehyde as an olefin and CO source
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Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co 2Rh2(CO)12 react with alkynes and α,β-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. α,β-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.
- Park, Kang Hyun,Jung, Il Gu,Chung, Young Keun
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p. 1183 - 1186
(2007/10/03)
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- Phosphine Catalyzed α-Arylation of Enones and Enals Using Hypervalent Bismuth Reagents: Regiospecific Enolate Arylation via Nucleophilic Catalysis
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Exposure of enones and enals to 20 mol % tributylphosphine in the presence of triarylbismuth(V) dichlorides results in regiospecific aryl transfer to the α-position of the enone or enal pronucleophile. These results represent the first examples of enolate
- Koech, Phillip K.,Krische, Michael J.
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p. 5350 - 5351
(2007/10/03)
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- Catalytic intermolecular Pauson-Khand-type reaction: Strong directing effect of pyridylsilyl and pyrimidylsilyl groups and isolation of Ru complexes relevant to catalytic reaction
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Some circumstantial evidence for the directing effect of the 2-pyhdylsilyl group in the Ru-catalyzed intermolecular Pauson-Khand-type reaction (PKR) of alkenyl(2-pyridyl)silane, alkyne, and carbon monoxide has been provided. Most importantly, we have succeeded in isolating several monometallic Ru complexes relevant to the catalytic reaction: Ru(vinylsilane)(CO)3 complexes and ruthenacyclopentene. While the stoichimetric reaction of the Ru(vinylsilane)(CO)3 complex with an alkyne led to the formation of the corresponding cyclopentenone (PKR product) at 100 °C, the ruthenacyclopentene intermediate was quantitatively produced at 50 °C. This complex was also converted to a cyclopentenone upon heating at 100 °C. Moreover, it was also found that the Ru(vinylsilane)(CO)3 complex and ruthenacyclopentene serve as catalysts in intermolecular PKR.
- Itami, Kenichiro,Mitsudo, Koichi,Fujita, Kazuyoshi,Ohashi, Youichi,Yoshida, Jun-Ichi
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p. 11058 - 11066
(2007/10/03)
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- Synthesis and structure-antifungal activity relationships of 3-aryl-5-alkyl-2,5-dihydrofuran-2-ones and their carbanalogues: Further refinement of tentative pharmacophore group
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Two series of 3-(substituted phenyl)-5-alkyl-2,5-dihydrofuran-2-ones related to a natural product, (-)incrustoporine, were synthesized and their in vitro antifungal activity evaluated. The compounds with halogen substituents on the phenyl ring exhibited selective antifungal activity against the filamentous strains of Absidia corymbifera and Aspergillus fumigatus. On the other hand, the influence of the lenghth of the alkyl chain at C(5) was marginal. The antifungal effect of the most active compound against the above strains was higher than that of ketoconazole, and close to that of amphotericin B. In order to verify the hypothesis about a possible relationship between the Michael-accepting ability of the compounds and their antifungal activity, a series of simple carbanalogues, 2-(substituted phenyl)cyclopent-2-enones, was prepared and subjected to antifungal activity assay as well.
- Pour, Milan,Spulak, Marcel,Balsanek, Vojtech,Kunes, Jiri,Kubanova, Petra,Buchta, Vladimir
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p. 2843 - 2866
(2007/10/03)
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- The utility of vinyl ethers and vinyl esters in the Khand reaction. The value of vinyl esters as ethylene equivalents and a modified synthesis of (+)-taylorione as an example
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The behaviour of various oxygenated alkenes in the Khand cyclisation reaction has been studied. Although several vinyl ethers reacted to give the expected oxygenated cyclopentenone products, usually with good levels of regioselectivity, the use of vinyl esters was found to afford, as the major products, reduced cyclopentenones in which the carbon-oxygen bond had been cleaved. This unexpected reaction was developed into an alternative procedure to using ethylene gas in the Khand reaction and was found to be applicable with a variety of alkyne substrates. The method was then extended to form the key step in the synthesis of the natural product (+)-taylorione (and (+)-nortaylorione).
- Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.,Robertson, Sarah M.
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p. 104 - 117
(2007/10/03)
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- Preparation of cycloalkanone oxime ethers via a free radical acylation approach
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Abstract: Radical-mediated annulation approaches for the formation of cycloalkanone oxime ethers are described. Based on radical acylation approaches, α-functionalized cycloalkanone oxime ethers, 1,3- and 1,4-cyclohexanedione oxime ethers are prepared.
- Kim,Kim,Yoon,Oh
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p. 1148 - 1150
(2007/10/03)
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- Catalytic intermolecular Pauson - Khand reactions in supercritical ethylene
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Ethylene is not only a substrate, but also a solvent: Catalytic intermolecular Pauson - Khand reactions of terminal alkynes were carried out in supercritical ethylene to provide 2-substituted cyclopentenones in moderate to high yields. Under these conditions, even a low pressure of CO (5 atm) is sufficient for the reaction to take place.
- Jeong, Nakcheol,Hwang, Sung Hee
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p. 636 - 638
(2007/10/03)
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- Vinyl esters as ethylene equivalents in the Khand annulation reaction
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A preparatively convenient and mild method for modified Khand cycloadditions is described; vinyl esters are employed as the olefinic reaction partner to provide cyclopentenone products more normally obtained with ethylene.
- Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.,Robertson, Sarah M.
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p. 2171 - 2172
(2007/10/03)
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- Synthesis of 2-phenyl-2-cycloalkenones via palladium-catalyzed tandem epoxide isomerization-intramolecular aldol condensation
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We have extended the scope of our palladium-catalyzed tandem epoxide isomerization/aldol condensation reaction to encompass intramolecular condensations, which provide facile access to conjugated cycloalkenones from epoxy aldehydes or diepoxides. For example, reaction of 5,6-epoxy-6- phenylhexanal with Pd(OAc)2-PBu3 catalyst in the presence of NaHCO3 and 3A molecular sieves forms 2-phenyl-2-cyclopentenone (80%). Similarly, 1,2;5,6-diepoxy-1-phenylhexane affords 3-methyl-2-phenyl-2-cyclopentenone (72%). The observation of dicarbonyl intermediates (e.g., 1-phenyl-2,5- hexanedione in the latter case) demonstrates that the reaction proceeds via Pd-catalyzed isomerization of the diepoxide to the diketone, followed by base-catalyzed aldol condensation.
- Kim, Ji-Hyun,Kulawiec, Robert J.
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p. 3107 - 3110
(2007/10/03)
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- Development of modified Pauson-Khand reactions with ethylene and utilisation in the total synthesis of (+)-taylorione
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Two complementary Pauson-Khanol annulation protocols for use with the gaseous alkene, ethylene, are described. These N-oxide promoted reactions (10 examples) are shown to proceed under both mild autoclave condition or, more conveniently, at atmospheric pressure. The developed methodology has been utilised as the key transformation in the total synthesis of the sesquiterpene (+)-taylorione which has been realised in a good overall yield from readily available (+)-2-carene.
- Donkervoort, Johannes G.,Gordon, Alison R.,Johnstone, Craig,Kerr, William J.,Lange, Udo
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p. 7391 - 7420
(2007/10/03)
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- Syntesis of 2-Cycloalken-1-ones
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The bromination of 2-alkyl- and 2-phenyl-1-cycloalkanones with N-bromosuccinimide and subsequent dehydrobromination with aniline gave the corresponding 2-cycloalken-1-ones.
- Shimazaki, Makoto,Huang, Zhi-Hui,Goto, Mikiko,Suzuki, Noriko,Ohta, Akihiro
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p. 677 - 678
(2007/10/02)
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- The effect of ultrasound and of phosphine and phosphine-oxides on the Khand reaction
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Ultrasonic irradation allows the Khand reaction to be conducted rapidly at low temperatures.Addition of phosphine oxides to the reaction mixture significantly increases yields in most cases.
- Billington, David C.,Helps, I. Malcolm,Pauson, Peter L.,Thomson, William,Willison, Debra
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p. 233 - 242
(2007/10/02)
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- REACTION OF α,β-UNSATURATED ALDEHYDES WITH HYDROGEN PEROXIDE CATALYSED BY BENZENESELENINIC ACIDS AND THEIR PRECURSORS
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Oxidation of α,β-unsaturated aldehydes with hydrogen perixide catalysed by benzeneselenic acids and their precursors has been investigated.Bis 2-nitrophenyl diselenide has proved to be the most effective catalyst.The major products resulting from the oxidation are vinyl formates (a) which on hydrolysis give saturated aldehydes or ketones (g) having the carbon chain shortened by one carbon atom, compared with the starting aldehydes.The minor products are formyloxyoxiranes (b), α-hydroxycarbonyl (e) and α-formyloxycarbonyl (f) compounds with the carbon chain shortened by one carbon atom.Carbonyl compounds d, formally derived from an oxidative fission of the carbon-carbon double bond, have been also isolated.Diformyloxy (4c) and formyloxyacetoxy phenylmethane (5c) have been isolated when cinnamaldehyde (4) or 1-phenyl-2-formyloxypropane (5a) were oxidized, respectively.Possible mechanisms of formation of these products are discussed.Similar products resulted when α,β-unsaturated aldehydes were oxidized with organic peroxy acids.
- Syper, Ludwik
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p. 2853 - 2872
(2007/10/02)
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- Oxidation of Styrene Derivatives by S2O82--CuII in Acetic Acid and Acetonitrile. Reaction Paths in Oxidations via Radical Cations
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β-Aryl carbonyl compounds are major products in the oxidation of a variety of styrene derivatives by S2O82--CuII.Evidence is presented that they arise via oxidation to a radical cation, nucleophilic addition of water to give a β-hydroxyalkyl radical, CuII oxidation to epoxide, and finally acid-catalyzed rearrangement.Data on oxidation of alkyl aromatics with additional functional groups are presented.With ether and amino groups, oxidation occurs at the functional group even when it is remote from the aryl nucleus.These and previous data are summarized to give a coherent picture of the various paths by which aryl side chains may be degraded via initial radical cation intermediates.
- Walling, Cheves,El-Taliawi, Gamil M.,Amarnath, Kalyani
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p. 7573 - 7578
(2007/10/02)
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- Ring Expansion of Succinoin Derivatives. New Synthetic Routes to Cyclopentenones
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Acid-catalysed ring expansion reactions of cyclobutane derivatives bearing a vicinal substituted-diol group give α-aryl and α-vinyl substituted cyclopentenones in good yields.
- Nakamura, Eiichi,Shimada, Jun-ichi,Kuwajima, Isao
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p. 498 - 499
(2007/10/02)
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- A NEW SYNTHESIS OF CYCLOPENTANONES BY THE RING EXPANSION OF 1-ACYL-1-CYCLOBUTANES
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A new ring expansion of 1-acyl-1-cyclobutanes to give 2-cyclopentanones and its application to the synthesis of 2-, 2,4-, or 2,5-substituted cyclopentanones were studied.
- Yamashita, Mitsuo,Onozuka, Junko,Tsuchihashi, Gen-ichi,Ogura, Katsuyuki
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- FACILE SYNTHESIS OF 2-SUBSTITUTED CYCLOPENTENONES
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An efficient synthesis of 2-substituted cyclopentenones is reported.Key reactions are the cyclopropanation of 2,2-dimethyl-3(2H)-furanone and subsequent conversion to the title compounds by oxidative fragmentation.
- Baldwin, S. W.,Blomquist, H. R.
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p. 3883 - 3886
(2007/10/02)
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- γ- and δ-epoxy sulfones. Formation of different ring-sized products upon reaction with CH3MgI or LiN2
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γ-Epoxy sulfones in which the epoxide function is terminal yield cyclopropylmethanol derivatives on reaction with methylithium or lithium diisopropylamide.In contrast, treatment of these epoxides with two equivalents of CH3MgI gives only cis-3-phenylsulfonylcyclobutanols.The cis-relationship between the OH and sulfonyl groups was proven in one instance by an X-ray stucture determination.Inernal γ-epoxy sulfones yield cyclopropylmethanols with all bases studied.All δ-epoxy sulfones studied furnished cis-3-phenylsulfonylcyclopentanols upon reaction with the Grignard reagent.These same epoxides gave either cyclopentanols or noncyclic products upon reaction with LDA; no cyclobutane ring containing products were obtained contrary to the expectations based on Stork's results with the corresponding epoxy nitriles (ref. 2).The mechanism of the Grignard-mediated reaction involves epoxide opening by iodide ion, α-sulfonyl Grignard formation, and, finally, cyclization.When LDA or CH3Li is used the products are formed by an intramolecular SN2 opening of the epoxide by an α-lithio sulfone.
- Decesare, John M.,Corbel, Bernard,Durst, Tony,Blount, John F.
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p. 1415 - 1424
(2007/10/02)
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