- Ionic crystals [M3O(OOCC6H5) 6(H2O)3]4[α-SiW 12O40] (M = Cr, Fe) as heterogeneous catalysts for pinacol rearrangement
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Complexation of trinuclear oxo-centered carboxylates with a silicododecatungstate resulted in the formation of ionic crystals of [M 3O(OOCC6H5)6(H2O) 3]4[α-SiW12O40]·nH 2O·mCH3COCH3 [M = Cr (Ia), Fe (IIa)]. Treatments of Ia and IIa at 373 K in vacuo formed guest-free phases Ib and IIb, respectively. Compounds Ib and IIb heterogeneously catalyzed the pinacol rearrangement to pinacolone with high conversion at 373 K, and the catalysis is suggested to proceed size selectively in the solid bulk.
- Uchida, Sayaka,Lesbani, Aldes,Ogasawara, Yoshiyuki,Mizuno, Noritaka
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Read Online
- The role of SET in the deprotection of (thio)ketals under photosensitization by π-acceptors
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Efficient deprotection of 2-methyl-2-tert-butyl-1,3-dithiolane and of the corresponding oxathiolane to give the ketone is obtained by photosensitization by a catalytic amount of aromatic nitriles (benzenetetracarbonitrile, TCB, and antracenedicarbonitrile, DCA the latter only in the presence of biphenyl) or of heterocyclic salts (triphenylpyrylium tetrafluoborate, TPPT, and methylacridinium perchlorate, MAP), in oxygen saturated solutions. The reaction involves SET to the excited π-acceptor and interception of the substrate radical cation either by oxygen (in the case of the heterocyclics) or by the superoxide anion (in the case of the nitriles). Triplet chloranil (Chl) acts both as oxidant and as proton acceptor, and thus deprotection is accompanied by formation of a stoichiometric amount of the hydroquinone ChlH2. The corresponding dioxolane is a weaker donor: SET occurs only with photoexcited TCB and causes C-C bond fragmentation, not deprotection. The other π-acceptors photosensitize the deprotection of the dioxolane, but in this case they act as Lewis acids (Chl gives a trimer under this condition). This method is unsatisfactory with protected aldehydes. The different reactivity of the radical cations of thioketals and of ketals and the scope of this deprotection method are discussed.
- Fasani, Elisa,Freccero, Mauro,Mella, Mariella,Albini, Angelo
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Read Online
- Acceleration of synthetic organic reactions using supercritical water: Noncatalytic Beckmann and pinacol rearrangements
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A high-pressure and high-temperature FTIR was used to study noncatalytic Beckmann and pinacol rearrangements using supercritical water (scH2O). Significant acceleration of Beckmann and pinacol rearrangements can be achieved by using scH2O, especially near the critical point, even in the absence of any acid catalysts. It has been demonstrated that scH2O acts effectively in the place of conventional acid catalysts for both the rearrangements. The rate of pinacol rearrangement using scH2O is significantly larger by a factor of 28200 than that in 0.871 M HCl solution at 46.7 MPa under distillation conditions. The activation energy for the former at 25 MPa was found to be markedly reduced to about one-third of that for the latter. The accelerated rates of reaction may be attributed to a great increase in the local proton concentration around the organic reactants. In addition, the nature of scH2O can be adjustable to weak acidity in the near-critical region, and then it does not catalyze the pinacol rearrangement, but opens a new reaction pathway from pinacol through a completely dehydrated product and then to a Diels-Alder adduct between the dehydrated products.
- Ikushima, Yutaka,Hatakeda, Kiyotaka,Sato, Osamu,Yokoyama, Toshirou,Arai, Masahiko
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Read Online
- Isomeric effects on the acidity of Al13Keggin clusters in porous ionic crystals
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We demonstrate a facile synthesis method of a porous ionic crystal (PIC) composed of the little-known δ-Keggin-type cationic polyoxoaluminum cluster ([δ-Al13O4(OH)24(H2O)12]7+, δ-Al13) with an oppositely-charged polyoxometalate, which enabled us to investigate the activity as a solid acid. The δ-Al13based PIC exhibited much higher activity in pinacol rearrangement, a typical acid-catalyzed reaction, than the PIC based on the well-known and thermodynamically stable rotational isomer (ε-Al13). This work is a rare example of rotational isomers of polyoxoaluminum clusters exhibiting remarkably different catalytic activities.
- Ogiwara, Naoki,Tamai, Nanako,Uchida, Sayaka,Weng, Zhewei,Yan, Li-Kai,Zhao, Congcong,Zhou, Wei
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supporting information
p. 8893 - 8896
(2021/09/10)
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- Catalytic Acceptorless Dehydrogenation of Aliphatic Alcohols
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We developed the first acceptorless dehydrogenation of aliphatic secondary alcohols to ketones under visible light irradiation at room temperature by devising a ternary hybrid catalyst system comprising a photoredox catalyst, a thiophosphate organocatalyst, and a nickel catalyst. The reaction proceeded through three main steps: hydrogen atom transfer from the α-C-H bond of an alcohol substrate to the thiyl radical of the photo-oxidized organocatalyst, interception of the generated carbon-centered radical with a nickel catalyst, and β-hydride elimination. The reaction proceeded in high yield under mild conditions without producing side products (except H2 gas) from various alcohols, including sterically hindered alcohols, a steroid, and a pharmaceutical derivative. This catalyst system also promoted acceptorless cross-dehydrogenative esterification from aldehydes and alcohols through hemiacetal intermediates.
- Fuse, Hiromu,Mitsunuma, Harunobu,Kanai, Motomu
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supporting information
p. 4493 - 4499
(2020/03/05)
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- Base-free oxidation of alcohols enabled by nickel(ii)-catalyzed transfer dehydrogenation
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An efficient nickel(ii)-catalyzed transfer dehydrogenation oxidation of alcohols is reported that relies on cyclohexanone as the formal oxidant and does not require the use of an external base. The synthetic utility of this protocol is demonstratedviathe facile oxidation of structurally complicated natural products.
- Ye, Danfeng,Liu, Zhiyuan,Sessler, Jonathan L.,Lei, Chuanhu
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supporting information
p. 11811 - 11814
(2020/10/13)
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- Production process of dichloro pinacolone (by machine translation)
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The production process is characterized in that the specific production process is as follows: S1: 2 - Chloropentane preparation. S2: pinacolone. S3: pinacolone rectification. S4: synthesis of dichloro-pinacolone. S5: treatment of by-products. In addition, by adopting formaldehyde addition in the chlorination reaction, the reaction rate 3 times or more can be inhibited, and reaction and cooling can be completed between a general reaction requirement 70 - 75 hours by adding formaldehyde, and cooling by adopting chilled water, so that the production efficiency is greatly improved 20 - 25 hours. (by machine translation)
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Paragraph 0011
(2020/12/29)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- Transfer-dehydrogenation of secondary alcohols catalyzed by manganese NNN-pincer complexes
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Novel catalytic systems based on pentacarbonylmanganese bromide and stable NNN-pincer ligands are presented for the transfer-dehydrogenation of secondary alcohols to give the corresponding ketones in good to excellent isolated yields. Best results are obtained using di-picolylamine derivatives as ligands and acetone as an inexpensive hydrogen acceptor. Besides high activity for benzylic substrates, aliphatic alcohols, as well as steroid derivatives, are readily oxidized in the presence of the optimal phosphorus-free catalyst.
- Budweg, Svenja,Junge, Kathrin,Beller, Matthias
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supporting information
p. 14143 - 14146
(2019/12/02)
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- Synthesis method of primary amine hydrochloride
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The invention discloses a synthesis method of primary amine hydrochloride. According to the synthesis method, in the presence of a gold complex, water and alkyne carry out catalytic hydrolysis to generate ketones, and then ketones and ammonium formate are catalyzed by a rhodium complex to generate primary amine. Compared with a conventional primary amine synthesis method, the synthesis method hasthe advantages that no alkali is added during the reaction process, no side product is generated, the atomic economy is good, the reaction conditions are mild, and the synthesis method has a wide prospect.
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Paragraph 0124-0127
(2019/03/09)
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- Silica-supported orthophosphoric acid (OPA/SiO2): preparation, characterization, and evaluation as green reusable catalyst for pinacolic rearrangement
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In this paper, we report an easy-to-prepare, cost-effective, efficient, and reusable silica-supported orthophosphoric acid (OPA) catalyst for pinacolic rearrangement. The surface properties of this catalyst were successfully characterized with the help of 31P NMR, TGA, DSC, FT-IR, titration, and microscopy. OPA, hydrogen bonded on the surface, is actually the active species and the reaction seems to occur in the liquid phase embedded in the silica support. As a consequence, the extracting solvent should be chosen with cautious to guarantee the recyclability of the catalyst. As example, pinacol rearrangement reactions were successfully realized with this catalyst and OPA/SiO2 proved to be as efficient as homogeneous orthophosphoric acid to promote the reaction of pinacol derivatives. When using dichloromethane as extracting solvent, OPA/SiO2 can be reuse up to ten times without a significant loss of activity. After ten runs, no physical damage of the catalyst has been observed by microscopy proving its suitability for such application.
- Billamboz, Muriel,Banaszak, Estelle
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p. 1029 - 1040
(2019/04/10)
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- Nucleophilic Isomerization of Epoxides by Pincer-Rhodium Catalysts: Activity Increase and Mechanistic Insights
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Herein, we present the efficient isomerization of epoxides into methyl ketones with a novel pincer-rhodium complex under very mild conditions. The catalyst system has an excellent functional group tolerance and a wide array of epoxides was tested. The corresponding methyl ketones were obtained in very high yields with excellent chemo- and regioselectivity. In addition, we investigated mechanistic details like the isomerization of the catalyst, and we obtained evidence that the catalytic cycle follows a β-hydride elimination-reductive elimination pathway after the nucleophilic ring opening of the epoxide.
- Tian, Yingying,Jürgens, Eva,Mill, Katharina,Jordan, Ronja,Maulbetsch, Theo,Kunz, Doris
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p. 4028 - 4035
(2019/06/25)
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- Dichloropinacolin production process
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The invention relates to a dichloropinacolin production process, which is characterized in that the specific production process is as follows: S1: preparation of 2-chloroisopentane; S2: synthesis of pinacone; S3: rectification of the pinacone; S4: synthesis of the dichloropinacolin; S5: treatment of byproducts. Excessive chlorine gas is adopted in a pinacone chlorination reaction, so that the pinacone can completely react; and in addition, formaldehyde is adopted to be added in the chlorination reaction, so that the generation of trichloropinacolin can be inhibited, and the reaction rate can be increased by more than 3 times at the same time; the general reaction takes 70-75 hours, and the reaction can be completed in 20-25 hours by adding formaldehyde.
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Paragraph 0009
(2019/04/17)
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- Regio- and chemoselective rearrangement of terminal epoxides into methyl alkyl and aryl ketones
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The development of the highly active pincer-type rhodium catalyst 2 for the nucleophilic Meinwald rearrangement of functionalised terminal epoxides into methyl ketones under mild conditions is presented. An excellent regio- and chemoselectivity is obtained for the first time for aryl oxiranes.
- Tian, Yingying,Jürgens, Eva,Kunz, Doris
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supporting information
p. 11340 - 11343
(2018/10/31)
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- Manganese complex-catalyzed oxidation and oxidative kinetic resolution of secondary alcohols by hydrogen peroxide
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The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn-oxo species. Density functional theory calculations revealed the difference in reaction energy barriers for H-atom abstraction from the α-CH bonds of R- and S-enantiomers by a chiral high-valent manganese-oxo complex, supporting the experimental result from the OKR of secondary alcohols.
- Miao, Chengxia,Li, Xiao-Xi,Lee, Yong-Min,Xia, Chungu,Wang, Yong,Nam, Wonwoo,Sun, Wei
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p. 7476 - 7482
(2017/10/30)
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- Sustainable production of pyromellitic acid with pinacol and diethyl maleate
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Herein, we report an unprecedented and sustainable route to synthesize pyromellitic acid (PMA), a monomer of polyimide, with pinacol and diethyl maleate which can be derived from lignocellulose. Analogously, a sustainable route to trimellitic acid (TMA) was also developed using pinacol and acrylate as the feedstocks.
- Hu, Yancheng,Li, Ning,Li, Guangyi,Wang, Aiqin,Cong, Yu,Wang, Xiaodong,Zhang, Tao
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supporting information
p. 1663 - 1667
(2017/06/05)
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- Solid Acid-Catalyzed Dehydration of Pinacol Derivatives in Ionic Liquid: Simple and Efficient Access to Branched 1,3-Dienes
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The selective dehydration of pinacol derivatives to branched 1,3-dienes is extremely challenging because of the predominance of pinacol rearrangement. Herein, we successfully achieve this goal by employing a recyclable solid acid/ionic liquid catalyst system. The dehydration of alkyl- and cycloalkyl-derived diols in an Amberlyst-15/[Emim]Cl system afforded the corresponding 1,3-dienes in good yields, while a Nafion/[Emim]Cl system was demonstrated to be a better catalyst system for the dehydration of aryl-substituted substrates. Our protocol features straightforward and simple access to branched 1,3-dienes, high chemoselectivity, a recyclable catalyst system, a facile separation of dienes just by decantation, and a broad substrate scope.
- Hu, Yancheng,Li, Ning,Li, Guangyi,Wang, Aiqin,Cong, Yu,Wang, Xiaodong,Zhang, Tao
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p. 2576 - 2582
(2017/05/31)
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- Sustainable Production of o-Xylene from Biomass-Derived Pinacol and Acrolein
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o-Xylene (OX) is a large-volume commodity chemical that is conventionally produced from fossil fuels. In this study, an efficient and sustainable two-step route is used to produce OX from biomass-derived pinacol and acrolein. In the first step, the phosphotungstic acid (HPW)-catalyzed pinacol dehydration in 1-ethyl-3-methylimidazolium chloride ([emim]Cl) selectively affords 2,3-dimethylbutadiene. The high selectivity of this reaction can be ascribed to the H-bonding interaction between Cl? and the hydroxy group of pinacol. The stabilization of the carbocation intermediate by the surrounding anion Cl? may be another reason for the high selectivity. Notably, the good reusability of the HPW/[emim]Cl system can reduce the waste output and production cost. In the second step, OX is selectively produced by a Diels–Alder reaction of 2,3-dimethylbutadiene and acrolein, followed by a Pd/C-catalyzed decarbonylation/aromatization cascade in a one-pot fashion. The sustainable two-step process efficiently produces renewable OX in 79 % overall yield. Analogously, biomass-derived crotonaldehyde and pinacol can also serve as the feedstocks for the production of 1,2,4-trimethylbenzene.
- Hu, Yancheng,Li, Ning,Li, Guangyi,Wang, Aiqin,Cong, Yu,Wang, Xiaodong,Zhang, Tao
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p. 2880 - 2885
(2017/07/25)
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- Boron trifluoride facilitated transesterification of dioxaborolanes
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The direct transesterification of dioxaborolanes (alkane-1,2-diol based boronate esters) was explored. Using BF3·OEt2, alkane-1,2-diol based mono- and bis-boronate esters (i.e., pinacol and ethylene glycol) have been converted quantitatively to either benzene-1,2-diol or alkane-1,3-diol based boronate esters. In the case of pinacol esters, esterification is facilitated by the accompanying pinacol rearrangement, thus shifting the reaction equilibrium.
- Kombala, Chathuri J.,Ekanayake, Dulamini I.,Gross, Dustin E.
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p. 3782 - 3786
(2017/09/09)
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- Synthesis method of high-purity pinacolone
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The invention discloses a synthesis method of high-purity pinacolone. The synthesis method of the high-purity pinacolone comprises the following steps: adding isoamylene and 30-39% of hydrochloric acid in zinc chloride as a hydrosilylation catalyst, and reacting at the temperature of 4-8 DEG C to prepare chloro t-pentane; condensing the chloro t-pentane and formaldehyde under an acidic condition, adding a condensation catalyst, and reacting for 5-7 hours at the temperature of 60-95 DEG C to prepare a pinacolone crude product; and adding 8-12% of water in the pinacolone crude product, directly heating and distilling with steam, and rectifying in a rectifying tower. By the method, the problem that a rectifying section is large in energy consumption and low in efficiency is solved, the pinacolone with high content of 98% is increased to be 45% from 15% in total yield, and the rectifying time is shortened to be 12 hours from 16 hours.
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Paragraph 0020; 0021; 0022; 0023; 0024; 0025-0034
(2017/02/28)
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- Reactivity of Lithium β-Ketocarboxylates: The Role of Lithium Salts
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Lithium β-ketocarboxylates 1(COOLi), prepared by the reaction of lithium enolates 2(Li+) with carbon dioxide, readily undergo decarboxylative disproportionation in THF solution unless in the presence of lithium salts, in which case they are indefinitely stable at room temperature in inert atmosphere. The availability of stable THF solutions of lithium β-ketocarboxylates 1(COOLi) in the absence of carbon dioxide allowed reactions to take place with nitrogen bases and alkyl halides 3 to give α-alkyl ketones 1(R) after acidic hydrolysis. The sequence thus represents the use of carbon dioxide as a removable directing group for the selective monoalkylation of lithium enolates 2(Li+). The roles of lithium salts in preventing the disproportionation of lithium β-ketocarboxylates 1(COOLi) and in determining the course of the reaction with bases and alkyl halides 3 are discussed.
- Berton, Mateo,Mello, Rossella,Williard, Paul G.,González-Nú?ez, María Elena
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supporting information
p. 17414 - 17420
(2017/12/15)
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- Ketone Formation from Carboxylic Acids by Ketonic Decarboxylation: The Exceptional Case of the Tertiary Carboxylic Acids
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For the reaction mechanism of the ketonic decarboxylation of two carboxylic acids, a β-keto acid is favored as key intermediate in many experimental and theoretical studies. Hydrogen atoms in the α-position are an indispensable requirement for the substrates to react by following this mechanism. However, isolated observations with tertiary carboxylic acids are not consistent with it and these are revisited and discussed herein. The experimental results obtained with pivalic acid indicate that the ketonic decarboxylation does not occur with this substrate. Instead, it is consumed in alternative reactions such as disintegration into isobutene, carbon monoxide, and water (retro-Koch reaction). In addition, the carboxylic acid is isomerized or loses carbon atoms, which converts the tertiary carboxylic acid into carboxylic acids bearing α-proton atoms. Hence, the latter are suitable to react through the β-keto acid pathway. A second substrate, 2,2,5,5-tetramethyladipic acid, reacted by following the same retro-Koch pathway. The primary product was the monocarboxylic acid 2,2,5-trimethyl-4-hexenoic acid (and its double bond isomer), which might be further transformed into a cyclic enone or a lactone. The ketonic decarboxylation product, 2,2,5,5-tetramethylcyclopentanone was observed in traces (0.2 % yield). Therefore, it can be concluded that the observed experimental results further support the proposed mechanism for the ketonic decarboxylation via the β-keto acid intermediate.
- Oliver-Tomas, Borja,Renz, Michael,Corma, Avelino
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p. 12900 - 12908
(2017/09/25)
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- Preparation method of 4, 4-dimethyl-3-oxo-methyl pentanoate
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The invention discloses a preparation method of 4, 4-dimethyl-3-oxo-methyl pentanoate. The method includes: taking pinacolone, sodium hydrogen and dimethyl carbonate as the raw materials, and using toluene as the solvent, carrying out stirring reaction at 55-60DEG C, then performing cooling, and at a pH of 4-5, preparing a 4, 4-dimethyl-3-oxo-methyl pentanoate crude product; and subjecting the 4, 4-dimethyl-3-oxo-methyl pentanoate crude product to distillation under the conditions of a vacuum degree of less than 10mm Hg and a temperature of 90-95DEG C. By means of the method provided by the invention, the 4, 4-dimethyl-3-oxo-methyl pentanoate has high distillation yield, the product purity is high, the main content is up to more than 98%, and the total yield is up to 96%.
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Paragraph 0016-0021
(2017/07/01)
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- Site-selective oxidation, amination and epimerization reactions of complex polyols enabled by transfer hydrogenation
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Polyoxygenated hydrocarbons that bear one or more hydroxyl groups comprise a large set of natural and synthetic compounds, often with potent biological activity. In synthetic chemistry, alcohols are important precursors to carbonyl groups, which then can be converted into a wide range of oxygen- or nitrogen-based functionality. Therefore, the selective conversion of a single hydroxyl group in natural products into a ketone would enable the selective introduction of unnatural functionality. However, the methods known to convert a simple alcohol, or even an alcohol in a molecule that contains multiple protected functional groups, are not suitable for selective reactions of complex polyol structures. We present a new ruthenium catalyst with a unique efficacy for the selective oxidation of a single hydroxyl group among many in unprotected polyol natural products. This oxidation enables the introduction of nitrogen-based functional groups into such structures that lack nitrogen atoms and enables a selective alcohol epimerization by stepwise or reversible oxidation and reduction.
- Hill, Christopher K.,Hartwig, John F.
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p. 1213 - 1221
(2017/11/28)
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- Ketone synthesis method through alkyne hydrolysis
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The invention discloses a ketone synthesis method through alkyne hydrolysis. The method comprises the following steps: adding alkyne, a catalyst [(IPr)AuCl], a solvent methanol, and water into a reactor, carrying out reactions for several hours at a temperature of 110 to 120 DEG C, cooling to the room temperature, carrying out rotary evaporation to remove the solvent, and performing column separation to obtain target compounds. Compared with conventional ionic gold catalyst, the provided method directly uses gold chloride [(IPr)AuCl] as the catalyst, alkyne is hydrolyzed into ketone, the yield is high, the selectivity is complete, and thus the method has an important meaning for organic synthesis and environment protection.
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Paragraph 0098-0101
(2017/05/02)
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- Introverted Phosphorus-Au Cavitands for Catalytic Use
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A preparative synthesis of an inwardly directed phosphoramidite-Au complex is described and a description of some of its catalytic performance. The molecular structure was determined by crystallographic analysis, which disclosed that the phosphoramidite ligand points “out” and places the complexed Au “in”. We investigated its catalytic activities and found that the inwardly directed Au is surrounded by three inert walls that provide new opportunities for supramolecular catalysis and study of reactive intermediates.
- Schramm, Michael P.,Kanaura, Mao,Ito, Kouhei,Ide, Masataka,Iwasawa, Tetsuo
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p. 813 - 820
(2017/01/18)
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- Control of Polymorphisms and Functions in All-Inorganic Ionic Crystals Based on Polyaluminum Hydroxide and Polyoxometalates
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Two kinds of polymorphs of all-inorganic ionic crystals were obtained by the combination of oppositely charged molecular ions (macroions) with Td symmetry, Keggin-type polyaluminum hydroxide [?-Al13O4(OH)24(H2O)12]7+ (Al13) and polyoxometalates (POMs) [α-CoW12O40]6- (POM6), [α-1,2,3-SiVV3W9O40]7- (POM7), or [α-1,2,3-SiVIVVV2W9O40]8- (POM8) in aqueous solutions. The needle-type crystals were grown by dissolution-recrystallization of the precipitates, which formed immediately by combining Al13 and POMs. On the other hand, the plate-type crystals were grown by adding inorganic salts (e.g., NaCl) into the aqueous solution containing the needle-type crystals: Dissolution of the needle-type crystals occurred followed by precipitation of the plate-type crystals, which is the more insoluble and stable polymorph with larger numbers of hydrogen bonds between the constituent ions. The plate-type crystals possess one-dimensional channels with large apertures (ca. 12 ? × 6 ?) and showed high activities as heterogeneous solid acid catalysts in pinacol rearrangement.
- Mizuno, Kosuke,Mura, Takuto,Uchida, Sayaka
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p. 4968 - 4974
(2016/11/04)
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- Palladium-Catalyzed Chemo- and Enantioselective C?O Bond Cleavage of α-Acyloxy Ketones by Hydrogenolysis
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A chemoselective C?O bond cleavage of the ester alkyl side-chain of α-acyloxy ketones was realized for the first time by a highly efficient palladium-catalyzed hydrogenolysis (S/C=6000, the highest catalytic efficiency by far). Furthermore, a kinetic resolution of α-acyloxy ketones was first developed by enantioselective hydrogenolysis with good yields and up to 99 % ee.
- Chen, Jianzhong,Zhang, Zhenfeng,Liu, Delong,Zhang, Wanbin
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p. 8444 - 8447
(2016/07/19)
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- Thiaporphyrin-mediated photocatalysis using red light
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Penetration of light through biological tissue improves in the near-IR windows beyond 650 nm. In an effort to explore the chemical reactivity accessible using this low-energy radiation, this study reveals catalysts and reactions that are experimentally viable with red light. Thiophene-containing porphyrin compounds are capable of catalytic, photo-reductive dehalogenation on an array of α-halo ketone model substrates with low catalyst loadings (0.1 mol%), in the presence of low energy, red light (>645 nm).
- Lee, Jingyu,Papatzimas, James W.,Bromby, Ashley D.,Gorobets, Evgueni,Derksen, Darren J.
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p. 59269 - 59272
(2016/07/06)
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- Synthetic method for tert-butyl methyl ketone
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The invention provides a synthetic method for tert-butyl methyl ketone. See the synthetic route in the description. According to the method, 2-chloro-2-methylbutane is used as a starting raw material, added into a reaction container and dissolved into solvent, then a certain amount of hydrochloric acid is added, a polymerization inhibitor of a certain quantity and a catalyst of a certain quantity are added, then solid paraformaldehyde is added into a reaction solution in batches at the reaction temperature of 50 DEG C-90 DEG C, and stirred for reaction until the reaction is complete, and the reaction time is 3-10 h; aftertreatment is carried out, and an organic phase of steam distillation reaction liquid is used for preparing tert-butyl methyl ketone. According to the synthetic method for tert-butyl methyl ketone, the reaction condition is mild, the tar content is low, the product yield is high, aftertreatment is simple, the adopted technical hydrochloric acid can be applied repeatedly and mechanically, and the synthetic method is suitable for industrialized production.
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Paragraph 0063; 0064; 0065
(2016/10/08)
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- Oxidation catalysis in air with CpIr: Influence of added ligands and reaction conditions on catalytic activity and stability
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We describe the systematic evaluation of CpIr catalysts for the aerobic oxidation of alcohols. Our results demonstrate turnover numbers up to 270 per [CpIrCl2]2 which have not been previously achieved for this reaction. Using air as the sole oxidant under base-free conditions, the effects of solvent systems and additives on the catalytic activity are documented systematically. We further elucidate the role of additives in catalyst decomposition processes and establish a novel buffer system which results in significant catalyst stabilization upon prolonged reaction times.
- Gunay, Ahmet,Mantell, Mark A.,Field, Kathleen D.,Wu, Wenbo,Chin, Michael,Emmert, Marion H.
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p. 1198 - 1205
(2015/02/19)
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- Regioselective hydration of terminal alkynes catalyzed by a neutral gold(I) complex [(IPr)AuCl] and one-pot synthesis of optically active secondary alcohols from terminal alkynes by the combination of [(IPr)AuCl] and Cp?RhCl[(R, R)-TsDPEN]
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A neutral gold(I) complex [(IPr)AuCl] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) was found to be a highly effective catalyst for the hydration of terminal alkynes, including aromatic alkynes and aliphatic alkynes. The desired methyl ketones were obtained in high yields with complete regioselectivities. Furthermore, a series of optically active secondary alcohols could be obtained in high yield with good to excellent enatioselectivities via one-pot sequential hydration/asymmetric transfer hydrogenation (ATH) from terminal alkynes by the combination of of [(IPr)AuCl] and Cp?RhCl[(R,R)-TsDPEN] (Cp? = pentamethylcyclopentadienyl, TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine). Notably, this research exhibited the potential of the direct use of neutral gold(I) complexes instead of cationic ones as catalysts for the activation of multiple bonds for organic synthesis.
- Li, Feng,Wang, Nana,Lu, Lei,Zhu, Guangjun
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p. 3538 - 3546
(2015/04/14)
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- Decarboxylation and simultaneous reduction of silver(I) β-ketocarboxylates with three types of coordinations
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A series of silver(I) β-ketocarboxylates were prepared by reaction of β-ketocarboxylic acids with silver nitrate in the presence of diethanolamine. The silver(I) β-ketocarboxylates decomposed over a narrow temperature range to form metallic silver, CO2, and the corresponding ketones. In addition, products derived from radical intermediates were detected by mass spectroscopic analysis for some silver(I) β-ketocarboxylates. Infrared and solid state 13C-NMR spectra of silver(I) β-ketocarboxylates suggested the presence of two types of structures involving a carbonyl group in addition to the dimeric eight-membered ring structure as in the structure of silver(I) stearate. The silver(I) β-ketocarboxylate model compound used was HCOCH2COOAg and its structures were determined using density functional theory (DFT) and atoms-in-molecules (AIM) methods. Three types of coordinations around the Ag ion differing significantly in Ag-O bond strengths were found. Based on the calculated structures and experimental results, the relationships between the structures and decomposition temperatures are discussed in terms of the thermal decomposition process.
- Hatamura, Mariko,Yamaguchi, Shunro,Takane, Shin-Ya,Chen, Yu,Suganuma, Katuaki
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p. 8993 - 9003
(2015/05/20)
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- A crystalline porous coordination polymer decorated with nitroxyl radicals catalyzes aerobic oxidation of alcohols
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A porous coordination polymer (PCP) has been synthesized employing an organic ligand in which a stable free radical, isoindoline nitroxide, is incorporated. The crystalline PCP possesses one-dimensional channels decorated with the nitroxyl catalytic sites. When O2 gas or air was used as the oxidant, this PCP was verified to be an efficient, recyclable, and widely applicable catalyst for selective oxidation of various alcohols to the corresponding aldehydes or ketones.
- Li, Liangchun,Matsuda, Ryotaro,Tanaka, Iku,Sato, Hiroshi,Kanoo, Prakash,Jeon, Hyung Joon,Foo, Maw Lin,Wakamiya, Atsushi,Murata, Yasujiro,Kitagawa, Susumu
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supporting information
p. 7543 - 7546
(2014/06/10)
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- In Situ Preparation of Au-SH@SO3H-SBA-15 Catalyst with Enhanced Activity and Durability in Alkyne Hydration
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A facile approach was developed for synthesizing Au-SH@SO3H-SBA-15 with ordered mesoporous channels by reducing Au3+ to Au nanoparticles with SH-group bonded to silica support, followed by in situ coordinating Au with the unreacted SH-groups. This catalyst exhibited high efficiency in alkyne hydration owing to the high activity of uniformly dispersed ultrasmall Au nanoparticles, the diminished diffusion limit due to the mesoporous structure, and the promoting effect of acidic SO3H-groups resulting from oxidation of the SH-group by Au3+. Meanwhile, the catalyst could be easily recycled and displayed strong durability owing to the strong hydrothermal stability of mesoporous structure and the enhanced stability against Au leaching due to the Au-SH coordination bond.
- Zhu, Fengxia,Li, Hexing
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p. 1072 - 1076
(2016/02/18)
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- New extraction procedure for protonated polyoxometalates prepared in aqueous-organic solution and characterisation of their catalytic ability
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Although POMs prepared in aqueous-organic solutions have been reported to exhibit interesting chemical properties and may be efficient catalysts, they could not be isolated in their protonated form using the normal extraction method. In this study, a new procedure of isolating protonated POMs, [S 2VxM18-xO62](4+x)- and [AsVxM12-xO40](3+x)- (M = Mo, W; x = 0-2), which were prepared in an aqueous-organic mixed solution, was developed by modifying and optimising the extraction conditions. Isolated protonated POMs were characterised using IR and Raman spectroscopy, and their acidity was measured using a Hammett indicator. The acidity of H4S 2W18O62, H5S2VW 17O62, H4S2Mo18O 62, and H3As2W18O62 was stronger than that of H3PW12O40. Their catalytic ability was investigated in multiple types of organic reactions, including pinacol rearrangement, acetal formation with benzaldehyde and ethylene glycol, and the Friedel-Crafts acylation of anisole with ethyl pyruvate. They exhibited greater catalytic ability than commercially available POMs such as H3PM12O40 and H4SiM 12O40 (M = Mo, W).
- Ueda, Tadaharu,Yamashita, Keisuke,Onda, Ayumu
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p. 181 - 187
(2014/11/08)
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- Zinc-acetic acid promoted reductive carbon-nitrogen bond cleavage reaction of α-aminoketones
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Scope and limitation of the reductive cleavage reaction of α-aminoketone systems with zinc-acetic acid are described. The carbon-nitrogen bond cleavage reaction was applicable to a wide range of α-aminoalkyl aryl ketones possessing various substituents on the aromatic ring. In contrast, α-aminoalkyl alkyl ketones with protons at the α'-position or α-aminoesters were sluggish to the carbon-nitrogen cleavage reaction.
- Ishikawa, Kyoko,Tomatsu, Miyuki,Nagase, Hiroshi,Fujii, Hideaki
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p. 1051 - 1063
(2014/01/17)
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- Catalysts for convenient aerobic alcohol oxidations in air: Systematic ligand studies in Pd/pyridine systems
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We report highly convenient Pd catalysts for the aerobic oxidation of alcohols, which are generated in situ by combining commercially available catalyst precursors. Systematic optimizations of the L- and X-type ligand environment and the employed additive allow the use of air as the sole oxidant without formation of Pd black. The resulting novel protocol provides quantitative yields of a broad variety of ketones and aldehydes.
- John, Lukas C.,Gunay, Ahmet,Wood, Andrew J.,Emmert, Marion H.
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p. 5758 - 5764
(2013/07/25)
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- Mechanistic investigations of a stable, highly active, extremely sterically shielded molecular gold catalyst
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An N-heterocyclic carbene gold complex IPr**AuNTf2 has been synthesized, spectroscopically investigated, structurally characterized, and used as a highly active and stable catalyst in the Hashmi phenol synthesis (IPr=1,3-di-p-tolylimidazol-2-ylidene with four di-tert-butylbenzhydryl ortho substituents, Tf=trifluoromethansulfonyl). A side reaction comprises an irreversible arene oxide ring opening with subsequent 1,2 methyl shift. The advantage of the steric demand of the ancillary ligand was explained by higher equilibrium concentrations of the cationic gold species, the circumvention of inactive dinuclear intermediates, and the inhibition of catalyst decomposition pathways. The methanol addition-hydration of alkynes featured a turnover-limiting proton transfer step of an alkenylgold catalyst resting state, indicated by a large primary kinetic isotope effect and an alkyne competition experiment.
- Weber, Simone G.,Zahner, David,Rominger, Frank,Straub, Bernd F.
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p. 2330 - 2335
(2013/09/02)
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- Effect of increasing the common anion concentration on the acid hydrolysis of glycosides
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Acid hydrolysis of glycoside compounds, methyl α-and β-d-glucopyranosides, was accelerated when KCl or KBr was added to an HCl or HBr system, respectively, consisting of H2O or aqueous 1,4-dioxane. The proton activity and solvent dissociation power of the system were not changed by the addition of the salt. These results confirm our previous suggestion that Br- and Cl- directly participate in the hydrolysis reaction. The extent of participation of the anions was also estimated.
- Phan, Hung Duy,Yokoyama, Tomoya,Matsumoto, Yuji
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p. 223 - 239
(2013/08/23)
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- Rhodium-catalyzed synthesis of 2,3-diaryl-1,4-diketones via oxidative coupling of benzyl ketones using α-thioketone oxidizing reagent
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RhH(PPh3)4 and 1,2-bis(diphenylphosphino)benzene (dppBz) catalyzed the oxidative coupling reaction of aryl benzyl ketones giving 2,3-diaryl-1,4-diketones in high yields. 3,3-Dimethyl-1-methylthio-2-butanone was used as the oxidizing
- Arisawa, Mieko,Li, Guangzhe,Yamaguchi, Masahiko
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supporting information
p. 1298 - 1301
(2013/03/13)
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- Mono, di and trifunctional cyclic organic peroxides: The effect of substituents and ring size on their thermolysis in 1,4-dioxan
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The thermal decomposition reaction of cyclic organic peroxides was studied in 1,4-dioxan at initial concentrations between ~10-4 and 10-2molL-1 and at a temperature interval between 100 and 170°C, according to the thermal stability of each compound. The kinetic behaviour observed in all systems studied follows a pseudo first order kinetic law up to at least ~86% of peroxide conversion. An important substituent effect is operative on the rate constant values and consequently on the activation parameters of the thermal decomposition reaction. The application of different treatments (compensation affect or a statistical treatment) on the kinetic data shows the existence of two sets of cyclic peroxides with comparable kinetic behaviour. Different peroxide-solvent interaction mechanisms can be considered within each series.
- Nesprias, Rosa,Eyler, Gladys,Canizo, Adriana
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p. 1080 - 1087
(2013/09/24)
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- Room-Temperature oxidation of secondary alcohols by bromate-bromide coupling in acidic water
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The use of environmentally benign reactions is currently an important topic in the field of synthetic chemistry. Here we report a high-yielding method to oxidize aliphatic or aromatic secondary alcohols into corresponding ketones using nonhazardous and inexpensive BrOH reagent at room temperature in water. BrOH reagent was derived from NaBr and NaBrO3 in aqueous acid. Based on the presented results, a mechanism was proposed for this oxidation. The reported method offers a facile, efficient procedure to produce various ketones with a low amount of side products. Taylor & Francis Group, LLC.
- Paeaekkoenen, Sanna,Pursiainen, Jouni,Lajunen, Marja
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experimental part
p. 534 - 540
(2011/12/04)
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- Ruthenium complexation in an aluminium metal-organic framework and its application in alcohol oxidation catalysis
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A ruthenium trichloride complex has been loaded into an aluminium metal-organic framework (MOF), MOF-253, by post-synthetic modification to give MOF-253-Ru. MOF-253 contains open bipyridine sites that are available to bind with the ruthenium complex. MOF-253-Ru was characterised by elemental analysis, N2 sorption and X-ray powder diffraction. This is the first time that a Ru complex has been coordinated to a MOF through post-synthetic modification and used as a heterogeneous catalyst. MOF-253-Ru catalysed the oxidation of primary and secondary alcohols, including allylic alcohols, with PhI(OAc) 2 as the oxidant under very mild reaction conditions (ambient temperature to 40 C). High conversions (up to >99 %) were achieved in short reaction times (1-3 h) by using low catalyst loadings (0.5 mol % Ru). In addition, high selectivities (>90 %) for aldehydes were obtained at room temperature. MOF-253-Ru can be recycled up to six times with only a moderate decrease in substrate conversion. In the frame: A ruthenium trichloride complex is loaded into an aluminium metal-organic framework by post-synthetic modification (see figure). This material is used in the heterogeneous catalysis of the oxidation of primary and secondary alcohols, including allylic alcohols, with PhI(OAc)2 as the oxidant under mild reaction conditions. High selectivities for aldehydes are obtained at room temperature. Copyright
- Carson, Fabian,Agrawal, Santosh,Gustafsson, Mikaela,Bartoszewicz, Agnieszka,Moraga, Francisca,Zou, Xiaodong,Martin-Matute, Belen
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supporting information
p. 15337 - 15344
(2013/01/15)
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- Organic reactivity of alcohols in superheated aqueous salt solutions: An overview
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The low dielectric constant and high self-dissociation constant of water in a temperature range between 150 and 250 °C make it a very appealing solvent for synthesis. Surprisingly, while organic chemistry in water at low temperature or around its critical point has been investigated in detail, very little seems to be known about the behaviour of organic molecules under hydrothermal conditions. The present work thus aims at shading some light on this field. As a start, we decided to investigate the reactions in which alcohols can undergo in water in the above-mentioned temperature range. Knowing that very strong salt effects on organic reactions have already been observed in super critical water, the impact of salt on the outcome of our tests was also investigated in detail.
- Avola, Sabine,Goettmann, Frederic,Antonietti, Markus,Kunz, Werner
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scheme or table
p. 1568 - 1573
(2012/10/07)
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- Direct participation of counter anion in acid hydrolysis of glycoside
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The mechanism of acid hydrolysis of glycoside has been investigated since the end of the 19th century accompanied by lots of literatures published on the mechanism, although little attention has surprisingly been paid to the action of counter anion of acid. In this paper, it was investigated whether or not counter anion of acid directly participates in acid hydrolysis of glycosides, methyl α- and β-d-glucopyranosides (MGP) in water, aqueous 74%, and 82% 1,4-dioxane systems. Because proton activity of a reaction system is the important rate-determining parameter in the universally acknowledged mechanism, it was carefully estimated in this study. The results suggested that bromide anion directly participates in the acid hydrolysis reaction of MGP in a water solvent system and the participation of bromide anion is further pronounced in aqueous 74% and 82% 1,4-dioxane solvent systems. It was also suggested that chloride anion directly participates in these dioxane solvent systems.
- Phan, Hung Duy,Yokoyama, Tomoya,Matsumoto, Yuji
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experimental part
p. 7382 - 7391
(2012/10/08)
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- Enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(iii)-salen complexes with N-bromosuccinimide as a powerful oxidant
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We demonstrate an efficient enantioselective oxidation of secondary alcohols catalyzed by Mn(iii)-salen complex using N-bromosuccinimide (NBS) as the oxidant. The new protocol is very efficient for the oxidative kinetic resolution of a variety of secondary alcohols, including ortho-substituted benzylic alcohols. The Royal Society of Chemistry 2012.
- Xu, Daqian,Wang, Shoufeng,Shen, Zhiqiang,Xia, Chungu,Sun, Wei
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supporting information
p. 2730 - 2732
(2012/11/07)
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- Efficient silver-free gold(I)-catalyzed hydration of alkynes at low catalyst loading
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The use of [(IPr)AuOH] as versatile, air- and moisture-stable pre-catalyst permits the in situ generation of the cationic gold(I) species [(IPr)Au]X after reaction with a Br?nsted acid. This catalytic system presents as a main advantage the lack of use of a silver salt activator or co-catalyst which is often air-, light- and moisture-sensitive. A general gold(I)-catalyzed procedure using this in situ activation at very low catalyst loading is reported for the hydration of a broad range of internal and terminal alkynes.
- Nun, Pierrick,Ramón, Rubén S.,Gaillard, Sylvain,Nolan, Steven P.
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experimental part
p. 7 - 11
(2011/02/17)
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- Polymer-mediated pinacol rearrangements
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Both poly(3,4-ethylenedioxythiophene) and poly(pyrrole) mediate a pinacol rearrangement of 1,2-diols. The yields of ketone or aldehyde products are comparable to those observed for treatment with mineral acids or Lewis acids. The advantage of this protocol is a two-phase reaction medium in hydrocarbon solvents that allows facile recovery of the products by simple filtration of the polymer and removal of solvents. Both the polymer and the hydrocarbon solvent may be recovered and used in subsequent reactions. Georg Thieme Verlag Stuttgart · New York.
- Pavlik, Christopher,Morton, Martha D.,Smith, Michael B.
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experimental part
p. 2191 - 2194
(2011/11/06)
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- Structure-reactivity relationship for alcohol oxidations via hydride transfer to a carbocationic oxidizing agent
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Second-order rate constants were determined for the oxidation of 27 alcohols (R1R2CHOH) by a carbocationic oxidizing agent, 9-phenylxanthylium ion, in acetontrile at 60°C. Alcohols include open-chain alkyl, cycloalkyl, and unsaturated alcohols. Kinetic isotope effects for the reaction of 1-phenylethanol were determined at three H/D positions of the alcohol (KIEα-D=3.9, KIEβ-D3=1.03, KIE OD=1.10). These KIE results are consistent with those we previously reported for the 2-propanol reaction, suggesting that these reactions follow a hydride-proton sequential transfer mechanism that involves a rate-limiting formation of the α-hydroxy carbocation intermediate. Structure-reactivity relationship for alcohol oxidations was deeply discussed on the basis of the observed structural effects on the formation of the carbocationic transition state (Cδ+-OH). Efficiencies of alcohol oxidations are largely dependent upon the alcohol structures. Steric hindrance effect and ring strain relief effect win over the electronic effect in determining the rates of the oxidations of open-chain alkyl and cycloalkyl alcohols. Unhindered secondary alkyl alcohols would be selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C7-C11 cycloalkyl alcohols react faster than cyclohexyl alcohol, whereas the strained C5 and C12 alcohols react slower. Aromatic alcohols would be efficiently and selectively oxidized in the presence of aliphatic alcohols of comparable steric requirements. This structure-reactivity relationship for alcohol oxidations via hydride-transfer mechanism is hoped to provide a useful guidance for the selective oxidation of certain alcohol functional groups in organic synthesis. Copyright
- Lu, Yun,Bradshaw, Joshua,Zhao, Yu,Kuester, William,Kabotso, Daniel
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p. 1172 - 1178
(2013/01/12)
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- EFFICIENT PROCESS FOR PRODUCING EPOXIDES BY OXIDATION OF OLEFINS IN THE HOMOGENEOUS GAS PHASE
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An economical one-step process is provided for the preparation of epoxides by oxidation of olefins in a homogeneous gas phase reaction, wherein the olefin is reacted in a flow reactor with a gas mixture of ozone and NO2 and/or NO as oxidants without use of a catalyst, and wherein ozone and NO2 and/or NO are mixed in a mixing chamber connected upstream to the flow reactor. The process is characterized in that the olefin in the reaction zone of the flow reactor is reacted at a reaction temperature of approximately 150° C. to approximately 450° C. and a pressure of 250 mbar to 10 bar with the gas mixture of the oxidant, that the carrier gas flow containing the olefin is heated in a preheating zone of the flow reactor to a temperature of 250° C. to 650° C., and that the gas mixture of the oxidant from the mixing chamber, having ambient temperature, is turbulently mixed with the olefin in the reaction zone of the flow reactor, so that the reaction temperature is reached during the mixing and the ratio of olefin-gas flow and gas flow of the oxidant is 5:1 to 1:1.
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Page/Page column 2
(2011/06/26)
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- H2O2-oxidation of alcohols promoted by polymeric phosphotungstate catalysts
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A novel polymeric phosphotungstate catalyst bearing a poly(ethylene oxide-pyridinium) matrix was developed that efficiently promoted oxidation of a variety of alcohols, including highly sterically demanding neopentyl alcohols, with hydrogen peroxide, to afford the corresponding carbonyl compounds in up to quantitative yield. The chemoselective oxidation of sterically hindered secondary alcohols in the presence of primary alcohols was achieved. The catalyst could be reused four times without any loss of catalytic activity.
- Yamada, Yoichi M.A.,Jin, Chung Keun,Uozumi, Yasuhiro
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supporting information; experimental part
p. 4540 - 4543
(2010/12/25)
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