- A Facile Method for the Sulfenyllactonization of Alkenoic Acids Using Dimethyl Sulfoxide Activated by Oxalyl Chloride
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A simple approach has been developed for the sulfenyllactonization of alkenoic acids using dimethyl sulfoxide activated with oxalyl chloride, in which methanesulfenyl chloride is proposed as the intermediate.
- Zhang, Ting,Dai, Yifeng,Cheng, Siwei,Liu, Yongguo,Yang, Shaoxiang,Sun, Baoguo,Tian, Hongyu
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- Stereochemical consequences in the deprotonation of enoates
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A cyclic transition structure for the deprotonation of enoates was proposed to rationalize the geometry of the deconjugated olefin and the substrate reactivity patterns.
- Galatsis, Paul,Manwell, Jeffrey J.,Millan, Scott D.
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- THE BARRIER FOR 1,2 HYDROGEN SHIFT IN DIALKYL CARBENES
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The products from the thermolysis of 4-diazirinopentanoic acid (2) allow the estimate of an experimental value for the Ea = 1.1 +/- 1 kcal.mol-1 for the barrier height for 1,2 H shift in dialkyl carbenes.
- Stevens, Ian D. R.,Liu, Michael T. H.,Soundararajan, N.,Paike, N.
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- Kinetics and Regioselectivity of Ring Opening of Substituted Cyclopropylmethyl Radicals
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Accurate analysis of the mixture of hydroxylamines 8 formed when suitable peroxides 4 undergo homolysis in the presence of the nitroxyl radical 1,1,3,3-tetramethylisoindolin-2-yloxy (T) has afforded rate constants for ring opening of the cyclopropylmethyl radicals 2a, 2c, 2dcis, 2dtrans, and 2e and cyclization of the but-3-enyl radicals 1a, 1c, and 1d.The presence of methyl substituents enhances the rates both of cyclization and of ring opening to give primary radicals.In the case of the trans-2-methylcyclopropyl radical, 2dtrans, this effect leads to preferential formation of the less thermodynamically stable possible product, 1d, below about 60 deg C.In general, the effects of substituents support the view that the transition structure for the cyclopropylmethyl-butenyl radical interconversion is dipolar.Combination of data from four sets of workers using three different kinetic techniques affords the following recommended Arrhenius equation for the cyclopropylmethyl radical clock reaction: log k1(2a) = 13.31 - 7.6/2.3RT.
- Beckwith, Athelstan L. J.,Bowry, Vincent W.
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- Highly Regioselective 5-endo-tet Cyclization of 3,4-Epoxy Amines into 3-Hydroxypyrrolidines Catalyzed by La(OTf)3
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Highly regioselective intramolecular aminolysis of 3,4-epoxy amines has been achieved. Key features of this reaction are (1) chemoselective activation of epoxides in the presence of unprotected aliphatic amines in the same molecules by a La(OTf)3 catalyst and (2) excellent regioselectivity for anti-Baldwin 5-endo-tet cyclization. This reaction affords 3-hydroxy-2-alkylpyrrolidines stereospecifically in high yields. DFT calculations revealed that the regioselectivity might be attributed to distortion energies of epoxy amine substrates. The use of this reaction was demonstrated by the first enantioselective synthesis of an antispasmodic agent prifinium bromide.
- Hoshino, Yoshihiko,Iwabuchi, Yoshiharu,Kuriyama, Yuse,Sasano, Yusuke,Uesugi, Shun-ichiro,Yamaichi, Aoto
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supporting information
p. 1961 - 1965
(2021/01/04)
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- Nickel-catalyzed electrocarboxylation of allylic halides with CO2
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Nickel-catalyzed regioselective electrocarboxylation of allylic halides with CO2at atmospheric pressure has been developed by adjusting reaction parameters, including catalyst, solvent, temperature and additive. β,γ-Unsaturated carboxylic acids were obtained in moderate to good yields and with high chain selectivity. This reaction shows tolerance to functional groups. In addition, cyclic voltammetry was performed to provide the possible mechanism of nickel-catalyzed CO2allylation.
- Wu, La-Xia,Deng, Fang-Jie,Wu, Lin,Wang, Huan,Chen, Tai-Jie,Guan, Ye-Bin,Lu, Jia-Xing
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p. 13137 - 13141
(2021/08/03)
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- Method for synthesizing (9Z, 12E)-9,12-tetradecadien-1-ol acetate
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The invention belongs to the technical field of green pesticide synthesis, and discloses a novel method for synthesizing (9Z, 12E)-9,12-tetradecadien-1-ol acetate. According to the method, malonic acid and 9-bromo-1-nonyl alcohol are used as two starting raw materials. The method comprises the following steps: carrying out a Knoevenagel condensation reaction on malonic acid and propionaldehyde inthe presence of piperidine acetate to generate (E)-3-pentenoic acid, then carrying out lithium aluminum hydride reduction to obtain (E)-3-penten-1-ol, carrying out bromination reaction, and refluxingwith triphenylphosphine in acetonitrile to obtain (E)-3-pentenyltriphenylphosphine bromide; carrying out a PCC oxidation reaction on 9-bromo-1-nonanol to obtain 9-bromononanal, and then reacting the 9-bromononanal with potassium acetate to obtain 9-acetoxynonanal; and finally, carrying out a Wittig reaction on (E)-3-pentenyltriphenylphosphine bromide and 9-acetoxynonanal so as to obtain (9Z, 12E)-9,12-tetradecadien-1-ol acetate. An E-type double bond is constructed by utilizing the Knoevenagel condensation reaction of malonic acid and propionaldehyde, and the method has the advantages of mildreaction conditions, environmental friendliness, simple synthetic route and the like.
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Paragraph 0011; 0026-0028
(2020/06/16)
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- Regioselective Isomerization of Terminal Alkenes Catalyzed by a PC(sp3)Pincer Complex with a Hemilabile Pendant Arm
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We describe an efficient protocol for the regioselective isomerization of terminal alkenes employing a previously described bifunctional Ir-based PC(sp3)complex (4) possessing a hemilabile sidearm. The isomerization, catalyzed by 4, results in a one-step shift of the double bond in good to excellent selectivity, and good yield. Our mechanistic studies revealed that the reaction is driven by the stepwise migratory insertion of Ir?H species into the terminal double bond/β-H elimination events. However, the selectivity of the reaction is controlled by dissociation of the hemilabile sidearm, which acts as a selector, favoring less sterically hindered substrates such as terminal alkenes; importantly, it prevents recombination and further isomerization of the internal ones.
- De-Botton, Sophie,Filippov, D.Sc. Oleg A.,Shubina, Elena S.,Belkova, Natalia V.,Gelman, Dmitri
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p. 5959 - 5965
(2020/10/15)
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- Probing the Mechanism of Photoaffinity Labeling by Dialkyldiazirines through Bioorthogonal Capture of Diazoalkanes
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Dialkyldiazirines have emerged as reagents of choice for biological photoaffinity labeling studies. The mechanism of crosslinking has dramatic consequences for biological applications where instantaneous labeling is desirable, as carbene insertions display different chemoselectivity and are much faster than competing mechanisms involving diazo or ylide intermediates. Here, deuterium labeling and diazo compound trapping experiments are employed to demonstrate that both carbene and diazo mechanisms operate in the reactions of a dialkyldiazirine motif that is commonly utilized for biological applications. For the fraction of intermolecular labeling that does involve a carbene mechanism, direct insertion is not necessarily involved, as products derived from a carbonyl ylide are also observed. We demonstrate that a strained cycloalkyne can intercept diazo compound intermediates and serve as a bioorthogonal probe for studying the contribution of the diazonium mechanism of photoaffinity labeling on a model protein under aqueous conditions.
- Am Ende, Christopher W.,Asare-Okai, Papa Nii,Fox, Joseph M.,Jemas, Andrew,O'brien, Jessica G. K.
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supporting information
p. 9415 - 9420
(2020/12/21)
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- Palladium-Catalyzed Amide-Directed Enantioselective Hydrocarbofunctionalization of Unactivated Alkenes Using a Chiral Monodentate Oxazoline Ligand
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A Pd-catalyzed amide-directed enantioselective hydrocarbofunctionalization of unactivated alkenes with C-H nucleophiles has been developed using a chiral monodentate oxazoline (MOXin) ligand. Various indoles react at C3 position with aminoquinoline-coupled 3-alkenamides to give γ addition products in good to excellent yield and enantioselectivity. This study represents an important advance of the development of chiral monodentate oxazoline ligands, which have been underexplored for asymmetric catalysis.
- Wang, Hao,Bai, Zibo,Jiao, Tangqian,Deng, Zhiqiang,Tong, Huarong,He, Gang,Peng, Qian,Chen, Gong
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supporting information
p. 3542 - 3546
(2018/03/21)
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- Selective Isomerization of Terminal Alkenes to (Z)-2-Alkenes Catalyzed by an Air-Stable Molybdenum(0) Complex
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Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO)4(PPh3)2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31P NMR reveals that cis-Mo(CO)4(PPh3)2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2-alkene.
- Becica, Joseph,Glaze, Owen D.,Wozniak, Derek I.,Dobereiner, Graham E.
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p. 482 - 490
(2018/02/17)
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- Regioselective Epoxidations by Cytochrome P450 3A4 Using a Theobromine Chemical Auxiliary to Predictably Produce N-Protected β- or γ-Amino Epoxides
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N-Protected β- and γ-amino epoxides are useful chiral synthons. We report here that the enzyme cytochrome P450 3A4 can catalyze the formation of such compounds in a regio- and stereoselective manner, even in the presence of multiple double bonds or aromatic substituents. To this end, the theobromine chemical auxiliary is used not only to control the selectivity of the enzyme, but also as a masked amine, and to facilitate product recovery. Theobromine predictably directed epoxidation at the double bond of the fourth carbon from the theobromine group. Unlike with most catalysts, the selectivity did not depend on electronic or steric factors but rather on the position of the olefin relative to the theobromine group. (Figure presented.).
- Polic, Vanja,Cheong, Kin Jack,Hammerer, Fabien,Auclair, Karine
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supporting information
p. 3983 - 3989
(2017/11/30)
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- A 3 - methylthio - γ - method for preparing lactone (by machine translation)
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The invention relates to shown in the following formula of 3 - methylthio - γ - method for preparing lactone: The method comprises the steps: aliphatic aldehyde with malonic acid in dimethyl sulfoxide in acetic acid piperidine salt under the catalytic action of the 100 °C the left and the right reaction, to obtain (E)- 3 - alkane olefine acid, yield 55 - 85%; in the - 78 - 10 °C will b a asian sulphone drop added to the oxalyl chloride in dichloromethane solution, then the (E)- 3 - alkane olefine acid added, at - 78 - 30 °C reaction, to obtain 3 - methylthio - γ - lactone, yield 60 - 82%. (by machine translation)
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Paragraph 0010; 0011
(2017/04/12)
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- A 2-methyl-3-tetrahydrofuran thiol acetate method for preparing trans isomer
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The invention relates to a simple preparation method for a 2-methyl-3-tetrahydrofuranthiol acetate cis-trans-isomer which has the structural formula as shown in the specification. The simple preparation method comprises the following steps: propionaldehyde and propandioic acid are subjected to condensation through Knoevenagel to obtain (E)-3-pentenoic acid, the (E)-3-pentenoic acid is reduced through lithium aluminum hydride to obtain (E)-3-pentene-1-alcohol, and then the (E)-3-pentene-1- alcohol reacts with methylsulfonyl chloride to obtain (E)-3-pentene-1-alcohol methanesulfonate, wherein the three-step overall reaction yield is 24%; (E)-3-pentene-1-alcohol methanesulfonate is oxidized with hydrogen peroxide and methanoic acid, and are cyclizated under the alkaline condition to obtain trans-2- methyl-3-hydroxytetrahydrofuran, and hydroxyl is transformed into methanesulfonate which reacts with thioacetic acid to obtain cis-2-methyl-3-tetrahydrofuranthiol acetate, wherein the three-step overall reaction yield is 61%; (E)-3-pentene-1-alcohol methanesulfonate is oxidized with potassium permanganate to obtain cis-2-methyl-3-hydroxytetrahydrofuran, and hydroxyl is transformed into methanesulfonate which reacts with thioacetic acid to obtain trans-2-methyl-3-tetrahydrofuranthiol acetate, wherein the three-step overall reaction yield is 63%.
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Paragraph 0010; 0011
(2016/12/01)
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- Enantioselective syntheses and sensory properties of 2-methyl-tetrahydrofuran-3-thiol acetates
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The enantioselective synthesis of four stereoisomers of 2-methyl-tetrahydrofuran-3-thiol acetate was achieved. The two enantiomers of the important intermediate cis-2-methyl-3-hydroxy-tetrahydrofuran were obtained by Sharpless asymmetric dihydroxylation (AD), whereas the two enantiomers of trans-2-methyl-3-hydroxy-tetrahydrofuran were derived from the corresponding optically active cis-isomers by Mitsunobu reaction. Each stereoisomer of 2-methyl-3-hydroxy-tetrahydrofuran went through mesylation and nucleophilic substitution to afford the corresponding product with specific configuration. (2R,3S)- and (2R,3R)-2-methyl-tetrahydrofuran-3-thiol acetate were obtained in 80% ee, whereas the (2S,3R)- and (2S,3S)-isomers were in 62% ee. The odor properties of the synthesized four stereoisomers were evaluated by gas chromatography - olfactometry (GC-O), which revealed perceptible di fferences among stereoisomers both in odor features and in intensities.
- Dai, Yifeng,Shao, Junqiang,Yang, Shaoxiang,Sun, Baoguo,Liu, Yongguo,Ning, Ting,Tian, Hongyu
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p. 464 - 468
(2015/01/30)
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- Isothiourea-mediated asymmetric functionalization of 3-alkenoic acids
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Isothiourea HBTM-2.1 promotes the catalytic asymmetric α- functionalization of 3-alkenoic acids through formal [2 + 2] cycloadditions with N-tosyl aldimines and formal [4 + 2] cycloadditions with either 4-aryltrifluoromethyl enones or N-aryl-N-aroyl diazenes, providing useful synthetic building blocks in good yield and with excellent enantiocontrol (up to >99% ee). Stereodefined products are amenable to further synthetic elaboration through manipulation of the olefinic functionality.
- Morrill, Louis C.,Smith, Samuel M.,Slawin, Alexandra M. Z.,Smith, Andrew D.
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p. 1640 - 1655
(2014/03/21)
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- Preparation and odour of cis- and trans-2-methyltetrahydrofuran-3-thiol acetates
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The preparation of cis- and trans-2-methyltetrahydrofuran-3-thiol acetates from (E)-3-penten-1-ol is reported. The mesylate of (E)-3-penten-1-ol was converted into trans- or cis-2-methyl-3-hydroxytetrahydrofuran by oxidation with H2O2 and HCOOH or with KMnO4. cis- or trans-2-Methyltetrahydrofuran-3-thiol acetate was prepared by mesylation and an SN2 nucleophilic substitution with AcSH from trans- or cis-2-methyl-3-hydroxytetrahydrofuran respectively. The configuration of the products was confirmed by their synthesis. Olfactory evaluation of cis- and trans-2-methyltetrahydrofuran-3-thiol acetates indicated some differences both in odour feature and intensity.
- Dai, Yifeng,Sun, Baoguo,Yang, Shaoxiang,Liu, Yongguo,Tian, Hongyu,Shao, Junqiang
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p. 236 - 239
(2014/05/06)
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- Rh2(R -TPCP)4-catalyzed enantioselective [3+2]-cycloaddition between nitrones and vinyldiazoacetates
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Rhodium-catalyzed reaction of vinyldiazoacetates with nitrones results in a formal [3+2]-cycloaddition to generate 2,5-dihydroisoxazoles with high levels of asymmetric induction. The cascade reaction begins with a vinylogous addition event, followed by an iminium addition ring-closure/hydride migration/alkene isomerization cascade. Dirhodium tetrakis(triarylcyclopropanecarboxylates) are the optimum catalysts for this process.
- Qin, Changming,Davies, Huw M. L.
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supporting information
p. 14516 - 14519
(2013/10/22)
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- Enantiodivergent and γ-selective asymmetric allylic amination
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Double agent: The title reaction using the guanidine catalyst 1 can deliver both enantiomers of the product with excellent enantioselectivity by judicious choice of the double bond geometry of the the β,γ-unsaturated carbonyl compound. Computational studies reveal the possible origin of the inversed enantioselectivity, and the potential for enantiodivergent synthesis chiral amine-containing substrates is attractive. Copyright
- Wang, Jianmin,Chen, Jie,Kee, Choon Wee,Tan, Choon-Hong
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p. 2382 - 2386
(2012/05/19)
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- Regioselective ring opening and isomerization reactions of 3,4-epoxyesters catalyzed by boron trifluoride
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Efficient ring opening of 3,4-epoxyesters with alcohols to produce 4-alkoxy-3-hydroxyesters and their isomerization into 4-ketoesters using boron trifluoride as the catalyst are presented. Both transformations are simple and efficient methods for the synthesis of the above named synthetically useful compounds.
- Izquierdo, Javier,Rodriguez, Santiago,Gonzalez, Florenci V.
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supporting information; experimental part
p. 3856 - 3859
(2011/09/19)
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- New reactions of anticancer-platinum complexes and their intriguing behaviour under various experimental conditions
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The anticancer platinum complexes here described react with organic substrates (such as acids, alkenes, alkynes) and catalyze transformations that can occur in biomolecules which contain unsaturated functions. We have analyzed the role of the platinum complexes in the observed reactions and studied the progress of the detected transformations upon variation of the reaction conditions. The Royal Society of Chemistry 2010.
- Aleman, Jose,Del Solar, Virginia,Cubo, Leticia,Quiroga, Adoracion G.,Navarro Ranninger, Carmen
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scheme or table
p. 10601 - 10607
(2011/01/05)
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- Method for regio- and stereoselective synthesis of (E)-Β,γ- unsaturated acids from aldehydes under solvent-free conditions
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Synthesis of (E)-β,-γunsaturated acids from aldehydes with malonic acid has been explored under solvent-free conditions. The modified Knoevenagel condensation reaction with N-methyl morpholine (NMM) as catalyst exhibits highly β,-γ regioselectivity and exclusively E-stereoselectivity. A mechanism accounting for both regio- and stereoselectivity has been proposed and preliminarily studied. Copyright Taylor & Francis Group, LLC.
- Zhang, Shi-Jie,Hu, Wei-Xiao
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experimental part
p. 3093 - 3100
(2010/12/19)
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- Anticancer platinum complexes as non-innocent compounds for catalysis in aqueous media
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An efficient cyclization of alkyne-acids to enol-lactones catalyzed by anticancer platinum(ii) and platinum(iv) compounds is described. These compounds are not only DNA-binding complexes; they can also catalyze reactions in solvents such as acetone, methanol, water or blood plasma.
- Aleman, Jose,Del Solar, Virginia,Navarro-Ranninger, Carmen
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supporting information; experimental part
p. 454 - 456
(2010/04/30)
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- A supramolecular catalyst for regioselective hydroformylation of unsaturated carboxylic acids
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(Chemical Equation Presented) The quest to capture the catalytic power of enzymes is one of the great challenges of modern chemistry. A novel system inspired by the principles of enzymatic catalysis combines recognition of the substrate and transition-metal catalysis (see scheme; Do = donor, FG = functional group) and mimics enzyme properties - high efficiency, substrate selectivity, and reaction-site selectivity.
- Smejkal, Tomas,Breit, Bernhard
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p. 311 - 315
(2008/09/19)
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- Stereoselective access to functionalized β-γ unsaturated acids
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Stereoselective synthesis of vinylstannanes bearing a carboxylic acid function was achieved from β-γ alkynoic acids via hydrostannation, stannylcupration or silastannation reactions. Regioselectivity is highly dependent on the nature of the stannylanions used and on protection of the carboxylic acid function.
- Thibonnet, Jér?me,Abarbri, Mohamed,Parrain, Jean-Luc,Duchêne, Alain
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p. 4433 - 4441
(2007/10/03)
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- Process for the preparation of 3-pentenoic acid from allylic butenyl alcohols or esters using a nickel catalyst
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Process for making 3-pentenoic acid acid by reacting an allylic butenyl alcohol or its corresponding ester with carbon monoxide in the presence of nickel, and a source of iodide.
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- Processes for producing aldehyde acids or salts
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This invention relates in part to processes for producing one or more substituted or unsubstituted aldehyde acids or salts, e.g., 5-formylvaleric acid or salt, which comprises subjecting one or more substituted or unsubstituted alkadienes, e.g., butadiene, to hydroxycarbonylation in the presence of a hydroxycarbonylation catalyst, e.g., a metal-organophosphorus ligand complex catalyst, and optionally neutralization with a base to produce one or more substituted or unsubstituted unsaturated acids or salts, e.g., pentenoic acid or salt, and subjecting said one or more substituted or unsubstituted unsaturated acids or salts to hydroformylation in the presence of a hydroformylation catalyst, e.g., a metal-organophosphorus ligand complex catalyst, to produce said one or more substituted or unsubstituted aldehyde acids or salts and/or one or more substituted or unsubstituted epsilon caprolactam precursors. This invention also relates in part to reaction mixtures containing one or more substituted or unsubstituted aldehyde acids or salts as the principal product(s) of reaction.
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- Process for the preparation of 3-pentenoic acid from butadiene using a nickel catalyst
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Process for making 3-pentenoic acid by reacting butadiene with carbon monoxide in the presence of nickel and an iodide source.
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- Synthesis of γ-hydroxy α,β-unsaturated amides by base induced isomerization of epoxy amides
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Treatment of 3,4-epoxyamides with LDA affords γ-hydroxy-α,β- unsaturated amides, usually with high (E)-selectivity. The 3,4-epoxyamides were prepared by the epoxidation of β,γ-unsaturated amides with meta- chloroperbenzoic acid.
- Brooks, Peter B.,Marson, Charles M.
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p. 9613 - 9622
(2007/10/03)
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- An in-depth study of the biotransformation of nitriles into amides and/or acids using Rhodococcus rhodochrous AJ270
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A variety of aliphatic, aromatic and heterocyclic nitriles have been readily hydrolysed into the corresponding amides and/or acids under very mild conditions using Rhodococcus sp. AJ270. The nitrile hydratase involved in this novel nitrile-hydrolysing microorganism efficiently hydrates most nitriles tested, irrespective of the electronic and steric effects of the substituents, to form the amides. Conversion of amides into acids catalysed by the associated amidase is rapid and efficient in most cases. Substrates bearing an adjacent substituent (which may be an ortho substituent on an aromatic nitrile, an adjacent heteroatom in a heterocyclic ring or a geminal substituent in an α,β-unsaturated nitrile) undergo slow hydrolysis of the amides allowing efficient amide isolation. The scope, limitations and reaction mechanism of this enzymatic process have been systematically studied. A molecular size of >7 A diameter and the presence of functions capable of metal complexation near to the nitrile inhibit hydrolysis.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1099 - 1104
(2007/10/03)
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- Activation of C-O and C-N Bonds in Allylic Alcohols and Amines by Palladium Complexes Promoted by CO2. Synthetic Applications to Allylation of Nucleophiles, Carbonylation, and Allylamine Disproportionation
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The direct activation of the C-O bonds in allylic alcohols catalyzed by palladium complexes has been accelerated by carrying out the reactions under CO2. On reaction with diethylamine, allyl alcohol can be converted into N,N-diethylallylamine in the presence of palladium complexes at room temperature under normal pressure of carbon dioxide. Allylation of various carbon nucleophiles such as β-keto esters and β-diketones can be achieved by using allylic alcohols directly in the presence of palladium complexes and CO2. Direct carbonylation of allylic alcohols into unsaturated carboxylic acids can be catalyzed by palladium complexes under the pressure of CO and CO2. Disproportionation of diallylamine into triallylamine and allylamine is also catalyzed by palladium complexes in the presence of CO2. On the basis of studies on the behavior of η3-allylpalladium hydrogencarbonate complexes with the nucleophiles, mechanisms are proposed to account for the palladium-catalyzed allylation processes influenced by CO2.
- Sakamoto, Masato,Shimizu, Isao,Yamamoto, Akio
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p. 1065 - 1078
(2007/10/03)
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- Regioselective Synthesis of β,γ-Unsaturated Acids by the Electrochemical Carboxylation of Allylic Bromides Using a Reactive-metal Anode
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Electrolysis of γ-mono and disubstituted allylic bromides in the presence of atmospheric pressure of carbon dioxide using a platinum cathode and a magnesium anode gave regioselectively the corresponding γ-mono and disubstituted β,γ-unsaturated carboxylic acids in 34-71percent yields.
- Tokuda, Masao,Kabuki, Takashi,Katoh, Yoshitaka,Suginome, Hiroshi
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p. 3345 - 3348
(2007/10/02)
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- Palladium-Catalyzed, Atmospheric Pressure Carbonylation of Allylic Halides under the Influence of Sodium Hydroxide or Alkoxides. A Facile Synthesis of β,γ-Unsaturated Acids
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The palladium-catalyzed, atmospheric-pressure carboxylation of allylic halides occurs readily in an aqueous sodium hydroxide/organic solvents two-phase system, giving β,γ-unsaturated acids.Phosphine complexes (I, L=m-(Ph2P)C6H4SO3Na; II, L=Ph3P) or Na2 (III) can be used as the catalyst.Atmospheric-pressure alkoxycarbonylation is realized under the influence of a homogeneous alcoholic solution of sodium alkoxide.Phosphine-free palladium complexes, such as 2 or III, are the favored catalyst. β,γ-Unsaturated esters are obtained in high yields.
- Okano, Tamon,Okabe, Nobuyuki,Kiji, Jitsuo
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p. 2589 - 2593
(2007/10/02)
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- The Thermal Decomposition of Diazirines: 3-(3-Methyldiazirin-3-yl)propan-1-ol and 3-(3-Methyldiazirin-3-yl)propanoic Acid
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The thermolyses of 3-(3-methyldiazirin-3-yl)propan-1-ol (1) and 3-(3-methyldiazirin-3-yl)propanoic acid (2) have been studied in solution over the temperature range 96-125 deg C.The reactions are unimolecular and fit linear Arrhenius plots with k(1)=1013.85+/-0.69exp-1/RT>s-1 and k(2)=1012.38+/-0.43exp-1/RT>s-1.The major products are the alkenes derived from the corresponding carbenes MeC2.CH2CH2CH2OH (3) and MeC2.CH2CH2CO2H (4).The new rate data, taken together with previous work, tend to confirm that diazirine thermolysis involves ring opening to a "complex" followed either by nitrogen loss or by isomerization to a diazo compound.Whereas (1) gives no product of closure onto oxygen, the acid (2) affords about 5percent γ-valerolactone.
- Stevens, Ian D. R.,Liu, Michael T. H.,Soundararajan, N.,Paike, N.
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p. 661 - 667
(2007/10/02)
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- Main Group Conjugated Organic Anion Chemistry. 3. Application of Magnesium-Anthracene Compounds in the Synthesis of Grignard Reagents
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Reaction of magnesium-arene compounds, , 1, and some silylanthracene, and/or tertiary amine analogues, with benzylic and allylic chlorides or bromides, and (Me3Si)3CCl, afford Grignard reagents, RMgX, in modest to high yield for chlorides and negligible to high yield for the bromides, in THF, toluene, and hexane at -10 to 20 deg C.Novel benzylic-type Grignard reagents prepared in high yield include those of 9-(chloromethyl)anthracene, 2-(chloromethyl)pyridine and 8-(chloro(or bromo)methyl)quinoline, and poly-Grignard reagents derived from 1,8-bis(chloromethyl)naphthalene, 2,2'-bis(chloromethyl)-1,1'-binaphthyl, and 1,3,5,-tris(chloro(or bromo)methyl)benzene.Grignard reagent formation occurs via electron-transfer reactions.Aryl and alkyl halides yield mainly products derived from addition of the halide across the 9,10-positions of the anthracenes, via nucleophilic substitution or collapse of a diradical cage 2+, (anthracene)-anion radical, RX-anion radical.>
- Harvey, Stephen,Junk, Peter C.,Raston, Colin L.,Salem, Geoffrey
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p. 3134 - 3140
(2007/10/02)
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- Hydrocarboxylation of butadiene to 3-pentenoic acid
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The preparation of 3-pentenoic acid by hydrocarboxylating butadiene with carbon monoxide and water in the presence of a rhodium-containing catalyst, an iodide promoter and certain inert halocarbon solvents, e.g., methylene chloride.
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- Temperature-Dependent Alkylation of γ-Phenyl β,γ-Unsaturated Acid and Ester Systems in Hexamethylphosphortriamide-Tetrahydrofuran Solutions Using Lithium Diisopropylamide
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The reactivities of some β,γ-unsaturated carboxylic acids and their methyl esters toward alkylation with methyl iodide using the lithium diisopropylamide-hexamethylphosphortriamide (LDA-HMPT) systems in THF have been investigated.The methylation selectivity of pent-3-enoic acid (2) and (1,2-dihydro-3-naphtyl)acetic acid (6) on using 1.0 equiv. of methyl iodide is high, the α-mono- to α,α-dimethylation ratios at -78 deg C being >20.The selectivity is substantially lower for styrylacetic acid (4) and increases with increasing temperature from 2.3 at -78 deg C to 8.5 at -10 deg C.The occurrence of dimethylation is ascribed to intermolecular proton exchange between the monomethylated species IIa and the nonmethylated species Ia.For the β,γ-unsaturated esters the methylation selectivity is somewhat higher than that for the corresponding carboxylic acids.
- Veen, Reinout H. van der,Cerfontain, Hans
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p. 342 - 346
(2007/10/02)
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- The electrosynthesis of carboxylic acids from carbon dioxide and butadiene
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Electroreduction of carbon dioxide in acetonitrile in the presence of butadiene gives rise to the formation of 3-pentenoic acid (2), 3-hexenedioic acid (3), and 3,7-decadienedioic and two isomeric C10-dicarboxylic acids (4) in high chemical yields.
- Tilborg, W. J. M. van,Smit, C. J.
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p. 437 - 438
(2007/10/02)
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