- Pyrazoles: 'one-pot' synthesis from arenes and carboxylic acids
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A rapid and efficient method for 'one-pot' synthesis of pyrazoles from (hetero)arenes and carboxylic acids via successive formation of ketones and β-diketones followed by heterocyclization with hydrazine has been developed. The utility of the RCOOH/TfOH/TFAA acylation system for intermediate production of ketones and 1,3-diketones is a key feature of this approach. The preliminary evaluation of the anticancer activity of the synthesized pyrazoles is performed.
- Gong, Ming,Kim, Jung Keun,Kovalev, Vladimir V.,Kovaleva, Olga V.,Shokova, Elvira A.,Tafeenko, Viktor A.,Wu, Yangjie
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supporting information
p. 5625 - 5638
(2020/08/21)
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- Electronic Asymmetry of an Annelated Pyridyl-Mesoionic Carbene Scaffold: Application in Pd(II)-Catalyzed Wacker-Type Oxidation of Olefins
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The two donor modules of an annelated pyridyl-mesoionic carbene ligand (aPmic) have different σ- and π-bonding characteristics leading to its electronic asymmetry. A Pd(II) complex 1 featuring aPmic catalyzes the oxidation of a wide range of terminal olefins to the corresponding methyl ketones in good to excellent yields in acetonitrile. The catalytic reaction is proposed to proceed via syn-peroxypalladation and a subsequent rate-limiting 1,2-hydride shift, which is supported by kinetic studies. The electronic asymmetry of aPmic renders a well-defined coordination sphere at Pd. The favored arrangement of reactants on the metal center features an olefin trans to the pyridyl module and a tbutylperoxide trans to the carbene. This arrangement gains added stability by the π-delocalization paved by the compatible orbitals on Pd, the pyridyl module, and the olefin that is perpendicular to the Pd(aPmic) plane. The π-interactions are absent in an alternate arrangement wherein the olefin is trans to the carbene. Density functional theory studies reveal the matching orbital overlaps responsible for the preferred arrangement over the other. This work provides an orbital description for the electronic asymmetry of aPmic.
- Bera, Jitendra K.,Dutta, Indranil,Kunnikuruvan, Sooraj,Reshi, Noor U Din,Saha, Sayantani,Yadav, Suman
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p. 11385 - 11393
(2020/11/23)
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- Isopropanol as a hydrogen source for single atom cobalt-catalyzed Wacker-type oxidation
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The first example of a heterogeneous cobalt catalytic system for Wacker-type oxidation catalyzed by a single atom dispersed Co-N/C catalyst using alcohol as the hydrogen source under an oxygen atmosphere is presented. By combining a well-designed, controlled experiment and various methods of characterization, we determined that single atom cobalt was the active center rather than nanoparticle or oxide counterparts.
- An, Yue,Chen, Bo,Gao, Shuang,Huang, Guanwang,Luo, Huihui,Shang, Sensen,Wang, Lianyue
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p. 2769 - 2773
(2020/06/17)
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- H2-Generation from Alcohols by the MOF-Based Noble Metal-Free Photocatalyst Ni/CdS/TiO2@MIL-101
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The synthesis of important classes of chemical compounds from alcohols helps to conserve Earth's fossil carbon resources, since alcohols can be obtained from indigestible and abundantly available biomass. The utilisation of visible light for the activation of alcohols permits alcohol-based C-N and C-C bond formation under mild conditions inaccessible with thermally operating hydrogen liberation catalysts. Herein, we report on a noble metal-free photocatalyst able to split alcohols into hydrogen and carbonyl compounds under inert gas atmosphere without the requirement of electron donors, additives, or aqueous reaction media. The reusable photocatalyst mediates C-N multiple bond formation using the oxidation of alcohols and subsequent coupling with amines. The photocatalyst consists of a CdS/TiO2 heterojunction decorated with co-catalytic Ni nanoparticles and is prepared on size-optimised colloidal metal-organic framework (MOF) crystallites.
- Tilgner, Dominic,Klarner, Mara,Hammon, Sebastian,Friedrich, Martin,Verch, Andreas,De Jonge, Niels,Kümmel, Stephan,Kempe, Rhett
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p. 842 - 847
(2019/08/26)
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- Efficient Palladium(0) supported on reduced graphene oxide for selective oxidation of olefins using graphene oxide as a ‘solid weak acid’
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Selective oxidation of olefin derivatives to ketones has made innovative development over palladium(0) supported on reduced graphene oxide. Compared to traditional Wacker oxidation, the novel method offers an economical and environment-friendly option by using graphene oxide (GO) as a ‘solid weak acid’ instead of classical homogeneous catalysts like H2SO4 and CF3COOH. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscopy images of Pd0/RGO showed that the nanoscaled Pd particles generated at the flake structure of reduced graphene oxide. Under optimized condition, up to 44 kinds of ketones with different structures can be prepared with excellent yields.
- Gao, Xi,Zhou, Jianhao,Peng, Xinhua
-
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- Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains
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Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents.
- Cvijeti?, Ilija N.,Verbi?, Tatjana ?.,Ernesto de Resende, Pedro,Stapleton, Paul,Gibbons, Simon,Jurani?, Ivan O.,Drakuli?, Branko J.,Zloh, Mire
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p. 1474 - 1488
(2017/11/17)
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- P -Selective (sp2)-C-H functionalization for an acylation/alkylation reaction using organic photoredox catalysis
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p-Selective (sp2)-C-H functionalization of electron rich arenes has been achieved for acylation and alkylation reactions, respectively, with acyl/alkylselenides by organic photoredox catalysis involving an interesting mechanistic pathway.
- Pandey, Ganesh,Tiwari, Sandip Kumar,Singh, Bhawana,Vanka, Kumar,Jain, Shailja
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supporting information
p. 12337 - 12340
(2017/11/20)
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- Acceptorless dehydrogenation and dehydrogenative coupling of alcohols catalysed by protic NHC ruthenium complexes
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A new family of protic NHC Ru complexes ligated with a phosphine-tethered imidazole moiety were prepared, which can act as excellent catalysts for acceptorless dehydrogenation of secondary alcohols and dehydrogenative coupling of primary and secondary alcohols, thus leading to the formation of a variety of carbonyl compounds with release of H2.
- Chang, Weihong,Gong, Xue,Wang, Shuizhong,Xiao, Ling-Ping,Song, Guoyong
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supporting information
p. 3466 - 3471
(2017/04/26)
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- Selective Oxidation of Styrene Derivatives to Ketones over Palladium(0)/Carbon with Hydrogen Peroxide as the Sole Oxidant
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Pd0/C catalyst exhibited excellent catalytic activity in the Wacker oxidation of styrene derivatives to corresponding ketones with hydrogen peroxide as a clean oxidant. Compared with the conventional Wacker system, the newly developed method offers a cost-efficient and environmentally friendly option without the use of a copper salt as a co-catalyst.
- Xia, Xiaomeng,Gao, Xi,Xu, Junhui,Hu, Chuanfeng,Peng, Xinhua
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supporting information
p. 607 - 610
(2017/03/11)
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- Taming of superacids: PVP-triflic acid as an effective solid triflic acid equivalent for Friedel-Crafts hydroxyalkylation and acylation
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The application of poly(4-vinylpyridine) supported trifluoromethanesulfonic acid (PVP-TfOH, 1:10) as a convenient solid superacid catalyst system in Friedel-Crafts reactions is described. In the presence of PVP-TfOH, one pot solvent-free synthesis of a wide variety of diarylacetic acid derivatives was achieved by Friedel-Crafts hydroxyalkylation reaction of glyoxylic acid with arenes under mild conditions. Acylation of both activated and deactivated aromatic compounds with acetyl chloride was also achieved using PVP-TfOH complex under solvent-free conditions at room temperature. As the polymer supported triflic acid was found to be a very efficient and an easy-to-handle solid acid, it can be a useful addition to environmentally more adaptable strong acid catalyst systems.
- Prakash, G.K. Surya,Paknia, Farzaneh,Kulkarni, Aditya,Narayanan, Arjun,Wang, Fang,Rasul, Golam,Mathew, Thomas,Olah, George A.
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p. 102 - 112
(2015/03/04)
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- 5-Aryl-1H-pyrazole-3-carboxylic acids as selective inhibitors of human carbonic anhydrases IX and XII
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Inhibitory activity of a congeneric set of 23 phenyl-substituted 5-phenyl-pyrazole-3-carboxylic acids toward human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms I, II, IX and XII was evaluated by a stopped-flow CO2 hydrase assay. These compounds exerted a clear, selective inhibition of hCA IX and XII over hCAI and II, with Ki in two to one digit micromolar concentrations (4-50 μM). Derivatives bearing bulkier substituents in para-position of the phenyl ring inhibited hCA XII at one-digit micromolar concentrations, while derivatives having alkyl substituents in both ortho- and meta-positions inhibited hCA IX with Kis ranging between 5 and 25 μM. Results of docking experiments offered a rational explanation on the selectivity of these compounds toward CA IX and XII, as well as on the substitution patterns leading to best CA IX or CA XII inhibitors. By examining the active sites of these four isoforms with GRID generated molecular-interaction fields, striking differences between hCA XII and the other three isoforms were observed. The field of hydrophobic probe (DRY) appeared significantly different in CA XII active site, comparing to other three isoforms studied. To the best of our knowledge such an observation was not reported in literature so far. Considering the selectivity of these carboxylates towards membrane-associated over cytosolic CA isoforms, the title compounds could be useful for the development of isoform-specific non-sulfonamide CA inhibitors.
- Cvijeti?, Ilija N.,Tan?, Muhammet,Jurani?, Ivan O.,Verbi?, Tatjana ?.,Supuran, Claudiu T.,Drakuli?, Branko J.
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p. 4649 - 4659
(2015/08/03)
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- Series of structural and functional models for the ES (enzyme-substrate) complex of the Co(II)-containing quercetin 2,3-dioxygenase
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A series of mononuclear CoII-flavonolate complexes [Co IILR(fla)] (LRH = 2-{[bis(pyridin-2-ylmethyl) amino]methyl}-p/m-R-benzoic acid; R = p-OMe (1), p-Me (2), m-Br (4), and m-NO2 (5); fla = flavonolate) were designed and synthesized as structural and functional models for the ES (enzyme-substrate) complexes to mimic the active site of the Co(II)-containing quercetin 2,3-dioxygenase (Co-2,3-QD). The metal center Co(II) ion in each complex shows a similar distorted octahedral geometry. The model complexes display high enzyme-type dioxygenation reactivity (oxidative O-heterocyclic ring opening of the coordinated substrate flavonolate) at low temperature, presumably due to the attached carboxylate group in the ligands. The reactivity exhibits a substituent group dependent order of -OMe (1) > -Me (2) > -H (3)14b > -Br (4) > -NO2 (5), and the Hammett plot is linear (ρ = -0.78). This can be explained as the electronic nature of the substituent group in the ligands may influence the conformation and redox potential of the bound flavonolate and finally bring different reactivity. The structures, properties, and reactivity of the model complexes show some dependence on the substituent group in the supporting model ligands, and there is some relationship among them. This study is the first example of a series of structural and functional ES models of Co-2,3-QD, with focus on the effects of the electronic nature of substituted groups and the carboxylate group of the ligands to the dioxygenation reactivity, that will provide important insights into the structure-property-reactivity relationship and the catalytic role of Co-2,3-QD.
- Sun, Ying-Ji,Huang, Qian-Qian,Zhang, Jian-Jun
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supporting information
p. 2932 - 2942
(2014/04/03)
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- Palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles: Synthesis of alkyl aryl ketones, diketone compounds, and 2-arylbenzo[b]furans
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A palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles has been developed, leading to a wide range of alkyl aryl ketones with moderate to excellent yields. Moreover, several dinitriles (e.g., malononitrile, glutaronitrile, and adiponitrile) were applicable to this process for the construction of 1,3-, 1,5-, or 1,6-dicarbonyl compounds. The scope of the developed approach is successfully explored toward the one-step synthesis of 2-arylbenzo[b]furans via sequential addition and intramolecular annulation reactions. The methodology accepted a wide range of substrates and is applicable to library synthesis.
- Wang, Xingyong,Liu, Miaochang,Xu, Long,Wang, Qingzong,Chen, Jiuxi,Ding, Jinchang,Wu, Huayue
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p. 5273 - 5281
(2013/07/26)
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- Fe3O4 nanoparticles as an efficient and magnetically recoverable catalyst for friedel-crafts acylation reaction in solvent-free conditions
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Application of Fe3O4 nanoparticles (NPs) as a robust, very efficient, and magnetically recoverable catalyst was investigated in Friedel-Crafts acylation (FCA) of ferrocene and aromatic compounds. This reaction was performed with acid chlorides in solvent-free conditions at room temperature. The catalyst was easily separated by an external magnetic field from the reaction mixture. The separated catalyst was recycled for several consecutive runs without appreciable loss of its catalytic activity. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications1 to view the free supplemental file. Copyright Taylor & Francis Group, LLC.
- Hoseini, S. Jafar,Nasrabadi, Hasan,Azizi, Mahboobeh,Salimi Beni, Alireza,Khalifeh, Reza
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p. 1683 - 1691
(2013/05/09)
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- Selective reductions of the carbonyl compounds and aryl halides with Ni-Al alloy in aqueous alkali medium
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The carbonyl compounds and the aryl halides are efficiently reduced by Ni-Al alloy powder, in aqueous alkali medium, with or without organic solvents. The relative reactivities in a series of structurally selected reducible compounds showed a sequence of reactivity in agreement with the mechanism involving a direct electron transfer from aluminum to the organic phase. In some cases an important change in reactivity with respect to conversion of the reducing reagent was notified. Most probably this complicated variability is the result of the changes in composition and morphology of the reacting Ni-Al alloy.
- Suceveanu, Mirela,Raicopol, Matei,Enache, Raluca,Finaru, Adriana,Rosca, Sorin I.
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experimental part
p. 690 - 695
(2012/06/04)
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- Method for Acylation of an Aromatic Compound
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A method for acylation of an aromatic compound, comprising reacting an aromatic compound and an acylating agent of the carboxylic acid type, in the presence of a Lewis acid and of a silylated reagent selected from the group consisting of halosilanes and halosiloxanes.
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Page/Page column 13
(2008/12/06)
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- Lanthanide triflate-catalyzed arene acylation. Relation to classical Friedel-Crafts acylation
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(Chemical Equation Presented) Lanthanide trifluoromethanesulfonates, Ln(OTf)3 (OTf- = trifluoromethanesulfonate), serve as effective precatalysts for the rapid, regioselective, intermolecular acylation of activated arenes. This contribution probes mechanism and metal ionic radius effects in the catalytic lanthanide triflate-mediated acylation of anisole with acetic anhydride. Kinetic studies of Ln(OTf)3 (Ln = La, Eu, Yb, Lu)-mediated anisole acylation with acetic anhydride in nitromethane reveal the rate law ν ～ k3 [Ln3+]1[acetic anhydride]1[anisole]1. Eyring and Arrhenius analyses yield ΔH? = 12.9 (4) kcal·mol-1, ΔS? = -44.8 (1.3) e.u., and Ea = 13.1 (4) kcal·mol-1 for Ln = Yb, with the negative ΔS? implying a highly organized transition state. The observed primary kinetic isotope effect of k H/kD = 2.6 ± 0.15 is consistent with arene C-H bond scission in the turnover-limiting step. The proposed catalytic pathway involves precatalyst formation via interaction of Ln(OTf)3 with acetic anhydride, followed by Ln3+-anisole π-complexation, substrate-electrophile σ-complex formation, and turnover-limiting C-H bond scission. Lanthanide size effects on turnover frequencies are consistent with a transition state lacking significant ionic radius-dependent steric constraints. Substrate-Ln3+ interactions using paramagnetic Gd3+ and Yb3+ NMR probes and factors affecting reaction rates such as arene substituent and added LiClO4 cocatalyst are also explored.
- Dzudza, Alma,Marks, Tobin J.
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p. 4004 - 4016
(2008/09/21)
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- Tf2O as a rapid and efficient promoter for the dehydrative Friedel-Crafts acylation of aromatic compounds with carboxylic acids
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The Friedel-Crafts acylation of aromatic compounds with carboxylic acids was investigated in the presence of Tf2O. The reaction was carried out efficiently and very rapidly under mild reaction conditions without the need of any catalyst.
- Khodaei, Mohammd Mehdi,Alizadeh, Abdolhamid,Nazari, Ehsan
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p. 4199 - 4202
(2008/02/05)
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- The synthesis of arylketones via Friedel-Crafts acyldegermylation
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Electron-rich and electron-neutral aryl trialkylgermanes are shown to be competent precursors to aryl ketones via Friedel-Crafts acyldegermylation. Given the previously demonstrated greater stability towards basic/nucleophilic conditions of arylgermanes as compared to arylsilanes/stannanes, these reactions significantly expand the utility of group 14 acyldemetalation in synthesis. This is exemplified by the cleavage of Ge-based linker models for solid-phase synthesis (SPS). Georg Thieme Verlag Stuttgart.
- Spivey, Alan C.,Gripton, Christopher J. G.,Noban, Catherine,Parr, Nigel J.
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p. 2167 - 2170
(2007/10/03)
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- Acetylation of aromatic compounds over H-BEA zeolite: The influence of the substituents on the reactivity and on the catalyst stability
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The acylation with acetic anhydride of six aromatic substrates with different features (degree of activation of the aromatic ring towards electrophilic substitution, number of rings, i.e., 1 or 2) was carried out in a batch reactor at 373 K over a H-BEA zeolite (Si/Al = 15) with nitrobenzene as a solvent. The acetylation rate was found to be very dependent on the degree of ring activation, with diffusion limitations playing only a limited role. The decrease of the rate with reaction time, which was very pronounced with poorly activated and deactivated substrates, is mainly due to the inhibiting effect of acetic acid and of the products of acetic anhydride condensation.
- Guidotti, Matteo,Canaff, Christine,Coustard, Jean-Marie,Magnoux, Patrick,Guisnet, Michel
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p. 375 - 383
(2007/10/03)
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- The Friedel-Crafts acylation of aromatic compounds with carboxylic acids by the combined use of perfluoroalkanoic anhydride and bismuth or scandium triflate
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Aromatic ketones were synthesized by solventless Friedel-Crafts acylation of anisole, mesitylene, xylenes, and toluene with acetic acid and benzoic acid in the presence of trifluoroacetic anhydride by use of bismuth or scandium triflate at 30°C. Toluene, benzene, and even deactivated substrate such as chlorobenzene were benzoylated by the combined use of heptafluorobutyric anhydride and bismuth triflate at 75-100°C. The catalyst could be easily recovered and reused repeatedly for the reaction.
- Matsushita, Yoh-Ichi,Sugamoto, Kazuhiro,Matsui, Takanao
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p. 4723 - 4727
(2007/10/03)
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- Efficient aromatic acylation using catalytic ytterbium(III) bis(trifluoromethylsulfonyl)amide activated by lithium perchlorate in nitromethane
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Various aromatic ketones were prepared in good to high yields by acylation using ytterbium bis(trifluoromethylsulfonyl) amide as catalyst in 4M lithium perchlorate in nitromethane.
- Nie, Jin,Gong, Yanwei,Zhang, Zhengbo,Liu, Wenming
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p. 708 - 709
(2007/10/03)
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- LiClO4-acyl anhydrides complexes as powerful acylating reagents of aromatic compounds in solvent free conditions
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The Friedel-Crafts acylation of various activated benzenes is smoothly carried out with acyl anhydrides in the presence of 2 equiv. of LiClO4, as reaction promoter, under solventless conditions.
- Bartoli, Giuseppe,Bosco, Marcella,Marcantoni, Enrico,Massaccesi, Massimo,Rinaldi, Samuele,Sambri, Letizia
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p. 6331 - 6333
(2007/10/03)
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- Efficient aromatic and heteroatom acylations using catalytic indium complexes with lithium perchlorate
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The combination of an indium complex with lithium perchlorate affords a potent system for the catalytic acylation of electron-rich aromatics and alcohols. The use of isopropenyl acetate as acyl donor results in cleaner methodology with acetone as the only by-product. The study has also revealed an indium-catalysed ketalisation reaction.
- Chapman, Christopher J.,Frost, Christopher G.,Hartley, Joseph P.,Whittle, Alan J.
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p. 773 - 775
(2007/10/03)
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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-
- Gallium nonafluorobutanesulfonate as an efficient catalyst in Friedel- Crafts acylation
-
Catalytic Friedel-Crafts acylation of even inactivated benzenes has been successfully carded out using a gallium compound. In the presence of a catalytic amount of gallium nonafluorobutanesulfonate (1-5 mol%), aromatics including inactivated benzenes such as fluorobenzene, chlorobenzene, and dichlorobenzene reacted with carboxylic acid chlorides or anhydrides to afford the corresponding aromatic ketones in good to excellent yields. Contrary to traditional understandings, catalytic Friedel-Crafts acylation was successfully carried out using the group 13 compound.
- Matsuo, Jun-Ichi,Odashima, Kazunori,Kobayashi, Shu
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p. 403 - 405
(2007/10/03)
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- Friedel-crafts reactions catalyzed by rare earth metal trifluoromethanesulfonates
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Rare earth metal trifluoromethanesulfonates (rare earth metal trifiates, RE(OTf)3) were found to be efficient catalysts for Friedel-Crafts acylation and alkylation. In the presence of a catalytic amount of RE(OTf)3, acylation of aromatic compounds having electron-donating substituents such as anisole, thioanisole, and mesitylene with acid anhydrides proceeded smoothly to afford the corresponding aromatic ketones in high yields. Although RE(OTf)3 alone is not effective for acylation of less reactive aromatics such as toluene, the combination of RE(OTf)3 and lithium perchlorate (LiClO4) enhanced the catalytic activity dramatically. Friedel-Crafts acylation reactions using rare earth metal perfluoroalkanesulfonates were also successfully performed in supercritical carbon dioxide (scCO2). Moreover, in the presence of a catalytic amount of RE(OTf)3, aromatic compounds reacted with benzyl chloride smoothly to afford the corresponding alkylation products in high yields. In these reactions, RE(OTf)3 could be easily recovered after the reactions were completed and could be reused without loss of activity.
- Kawada, Atsushi,Mitamura, Shuichi,Matsuo, Jun-Ichi,Tsuchiya, Takehiro,Kobayashi, Shu
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p. 2325 - 2333
(2007/10/03)
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- Silica gel supported chromium trioxide: An efficient reagent for oxidative cleavage of oximes to carbonyl compounds under mild condition
-
A facile, efficient oxidative deblocking of aldoximes and ketoximes to their corresponding aldehydes and ketones have been achieved by using silica gel supported chromium trioxide.
- Bendale, Pravin M.,Khadilkar, Bhushan M.
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p. 665 - 669
(2007/10/03)
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- Lanthanide bis(trifluoromethylsulfonyl)amides as effective reusable catalysts for catalytic Friedel-Crafts acylation
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By using a catalytic amount of a lanthanide bis(trifluoromethylsulfonyl)amide, Ln(NFf2)3, the Friedel-Crafts acylation of substituted benzene proceeds smoothly under mild conditions and the catalysts are easily recovered from the reaction mixture.
- Nie, Jin,Xu, Jun,Zhou, Guangyong
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p. 446 - 447
(2007/10/03)
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- Intermolecular character of the Fris rearrangement in the series of acyloxycoumarins
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In the study of the Fris rearrangement in the series of 7-and 4-acyloxycoumarins we obtained certain data indicating intermolecular character of the rearrangement. The Fris rearrangement of a mixture of 7-benzoyloxy-4-metylcoumarin and 7-acetoxycoumarin results in formation of four reaction products in approximately equal molar ratio. Also, four products were obtained in the Fris rearrangement of 7-and 4-acyloxycoumarins in the presence of hydroxycoumarins. The Fris rearrangement of acyloxycoumarins in the presence of m-xylene at acylcoumarin-m-xylene ratio of 1:6 leads to the corresponding hydroxycoumarins and acylated m-xylenes. Intermediate formation of acylium ions was also detected by evolution of carbon monooxide at the Fris rearrangement of 7-pyvaloyloxy-and 7-isobutyryloxy-4-methylcoumarins. A product of intermolecular migration, 3-acetyl-4-hydoxy-6-methylcoumarin, was discovered also in the rearrangement of 4-acetoxycoumarin in the presence of 4-hydoxy-6-methylcoumarin catalyzed by phosphorus oxychloride.
- Kravchenko,Chibisova,Traven'
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p. 899 - 909
(2007/10/03)
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- Acid-mediated specific α,α-diarylation and α-monoarylation reactions of pyruvic acid with/without decarbonylation
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Pyruvic acid (3) was found to be arylated chemoselectively at the α- ketocarbonyl carbon in P2O5-MsOH affording decarbonylative α,α-diarylated products 5, decarbonylative α-monoarylated compounds 6, or non- decarbonylative α,α-diarylated adducts 7 depending on the reactivity of arenes (4a-g), in contrast to Lewis acid-catalyzed reaction of its acid chloride (2).
- Yonezawa, Noriyuki,Hino, Tetsuo,Kinuno, Tsuyoshi,Matsuki, Toshiyuki,Ikeda, Tomiki
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p. 1687 - 1695
(2007/10/03)
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- Microwave promoted regeneration of carbonyl compounds from oximes using silica supported chromium trioxide
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Silica supported chromium trioxide was found to be an efficient reagent for the oxidative cleavage of oximes to the corresponding aldehydes and ketones in 'dry media', under microwave irradiation in a domestic microwave oven.
- Bendale, Pravin M.,Khadilkar, Bhushan M.
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p. 5867 - 5868
(2007/10/03)
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- Ln(OTf)3-LiClO4 as reusable catalyst system for Friedel-Crafts acylation
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Lithium perchlorate is found to accelerate Ln(OTf)3-catalysed Friedel-Crafts acylation; the catalytic system, Ln(OTf)3-LiClO4, is easily recovered from the reaction mixture by simple extraction and can be reused without decrease in its catalytic activity.
- Kawada, Atsushi,Mitamura, Shuichi,Kobayashi, Shu
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p. 183 - 184
(2007/10/03)
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- Aromatic Spiranes XX [1]: Syntheses of Dimethylsubstituted 2-Carboxymethyl-indan-1-ones and Benzylchlorides as Synthones for Syntheses of di- to tetramethylsubstituted Spirobiindandiones
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The isomeric dimethyl methylbenzoates 5, obtained from the bromides via Grignard reactions with dimethylcarbonate, were reduced with LiAlH4 to the hydroxymethyl derivatives 6. The latter were then transformed both to the benzylchlorides 7 (with SOCl2) and to the aldehydes 8 (with pyridinium chlorochromate). Knoevenagel-Doebner reaction of 8 afforded the acrylic acids 9 which (after hydrogenation to 11) were cyclized to the desired indanones 12 with polyphosphoric acid. On the other hand, 12c and 12e were prepared from dimethyl 3-chloropropiophenone (14) by warming with sulfuric acid. After NaH-catalyzed reaction with dimethylcarbonate, the indanones 12 gave the ketoesters 15 which then could be hydrogenated to the indanes 16. All reactions proceeded with satisfactory to excellent yields (60-90%).
- Neudeck
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p. 185 - 200
(2007/10/03)
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- Catalytic Friedel-Crafts Acylation Reactions Using Hafnium Triflate as a Catalyst in Lithium Perchlorate-Nitromethane
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Catalytic Friedel-Crafts acylation reactions were performed by using hafnium trifluoromethanesulfonate (hafnium triflate, Hf(OTf)4) as a catalyst.The catalytic activity of the Lewis acid catalyst was much improved in lithium perchlorate-nitromethane (LiClO4-MeNO2) and the yield was up to 250,000percent based on the catalyst.Various substituted benzenes reacted with acid annhydrides in the presence of a catalytic amount of Hf(OTf)4 to give the corresponding aromatic ketones in high yields.
- Hachiya, Iwao,Moriwaki, Mitsuhiro,Kobayashi, Shu
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p. 409 - 412
(2007/10/02)
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- Hafnium(IV)Trifluoromethanesulfonate, An Efficient Catalyst for the Friedel-Crafts Acylation and Alkylation Reactions
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Hafnium(IV) trifluoromethanesulfonate (hafnium(IV) triflate, Hf(OTf)4) was synthesized from hafnium tetrachloride and trifluoromethanesulfonic acid.The triflate thus prepared was found to be effective in the catalytic Friedel-Crafts acylation reactions of various substituted benzenes with acid anhydrides in lithium perchlorate-nitromethane (LiClO4-MeNO2).Lithium perchlorate-nitromethane is an excellent solvent system, and the catalytic activity of the Lewis acid was much improved in this medium.The product was obtained in up to 250000percent molar amounts baaed on the catalyst.Hafnium(IV) triflate was also found to be quite effective in the catalytic Friedel-Crafts alkylation reactions of aromatic compounds with alkyl chlorides.The reactions proceeded smoothly in the presence of 5percent molar amount of Hf(OTf)4 and 50percent molar amount of LiClO4 by using a slow addition procedure.
- Hachiya, Iwao,Moriwaki, Mitsuhiro,Kobayashi, Shu
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p. 2053 - 2060
(2007/10/02)
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- Tetralin formate ester aroma chemicals
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The present invention relates to novel formate ester tetralin compounds having fragrant musk-like aroma.
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- Lanthanide Trifluoromethanesulfonates as Reusable Catalysts: Catalytic Friedel-Crafts Acylation
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The Friedel-Crafts acylation of substituted benzenes proceeds smoothly by using a catalytic amount of a lanthanide trifluoromethanesulfonate , which is easily recovered from the reaction mixture and reused without a decrease in catalytic activity.
- Kawada, Atsushi,Mitamura, Shuichi,Kobayashi, Shu
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p. 1157 - 1158
(2007/10/02)
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- Methyl Group Effect on the Proton Affinity of Methylated Acetophenones Studied by Two Mass Spectrometric Techniques
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The proton affinities (PA) of all isomeric dimethylacetophenones were determined using the "kinetic method" with a tandem mass spectrometer and by measurements of the proton transfer equilibrium in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry.For both methods acetophenone and p-methylacetophenone, with well known PA values, were used as reference bases.Both methods yielded identical PA values for all dimethylacetophenones.The PA of the dimethylacetophenones were in a narrow range between 872 and 880 kJ mol-1 except for 2,6-dimethylacetophenone, for which a PA of 856 kJ mol-1 was found.The results are discussed in terms of possible mesomeric structures stabilizing the positive charge with regard to the substitution pattern in the phenyl ring.Obviously, the significant smaller PA of 2,6-dimethylacetophenone compared with the other isomers is due to the distortion of the conjugation of the C-O double bond with the aromatic ? system.
- Kukol, A.,Strehle, F.,Thielking, G.,Gruetzmacher, H.-Fr.
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p. 1107 - 1110
(2007/10/02)
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- Organic Peroxides, XXV. - The Reactivity of Benzylic Methyl Groups at the Barton Type Cyclization of Organic Hydroperoxides
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On the earlier reported cyclization conditions the hydroperoxides 1a-d yield the 2,3-dioxabenzacyclooctenes 3a, 3b and 2,3-dioxabenzocyclononenes 3c, 3d as well as the 1,2-dioxolanes 4a, 4b and 1,2-dioxanes 4c, 4d, respectively.Starting from the hydroperoxide 2 the 1,2-dioxolane 7 is the only cyclic peroxide obtained.The symmetric and the unsymmetric dialkyl peroxides 5, 6, 8, and 9 are obtained in all cases. - On the reaction of the hydroperoxides 1a, 1c, and 1d in acetic acid the cyclization is reduced to a very small extend.The symmetric dialkyl peroxides 5a, 5c, and 5d and the alkyl methyl peroxides 10a, 10c, and 10d are obtained in low yields. - The relatively high yields of the peroxides 3 are discussed on the basis of stereo-electronic effects.
- Kropf, Heinz,Wallis, Helmut von,Bartnick, Lily
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p. 624 - 634
(2007/10/02)
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- PALLADIUM(O) AND PHASE TRANSFER CATALYZED CONVERSION OF AZIRINES TO STYRYLINDOLES
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2-Styrylindoles were obtained in modest yields by the exposure of azirines to carbon monoxide, a palladium(O) catalyst, sodium hydroxide, benzene as the organic phase, and benzyltriethylammonium chloride as the phase transfer agent.The reaction is sensitive to the atmosphere used.
- Alper, Howard,Mahatantila, Chulangani P.
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p. 2025 - 2028
(2007/10/02)
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- Carboxylic Trifluoromethanesulfonic Anhydrides as Highly Effective Acylation Agents. - Perfluoroalkanesulfonic Acid Catalyzed Acylation of Arenes
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Arene- and alkanecarboxylic trifluoromethanesulfonic anhydrides 2 and 5 are highly effective acylation agents, which react without Friedel-Crafts catalysts even with deactivated aromatics to yield aryl ketones 3 and 6, respectively.Acylation of arenes with carbonyl chlorides 4 and catalytic amounts of perfluoroalkanesulfonic acid gives ketones 3 and 6, resp., in good yields.Under similar conditions other strong Broensted acids show a considerably smaller degree of catalytic effect.
- Effenberger, Franz,Sohn, Erich,Epple, Gerhard
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p. 1195 - 1208
(2007/10/02)
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- A SIMPLE TWO-STEP PARA-DIACETYLATION OF BENZENE AND P-XYLENE
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Aromatic hydrocarbons (benzene, p-xylene) are conveniently p-diacetylated by the regiospecific reductive p-disilylation/diacetylation process, followed by oxidative aromatization.The reaction uses trimethylchlorosilane which is recovered during the course of reaction.It gives diacetyl cyclohexadiene intermediates, novel species which prove relatively stable in an inert atmosphere.
- Laguerre, Michel,Dunogues, Jacques,Calas, Raymond
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p. 831 - 834
(2007/10/02)
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