- Selective Activation of Unstrained C(O)-C Bond in Ketone Suzuki-Miyaura Coupling Reaction Enabled by Hydride-Transfer Strategy
-
A Rh(I)-catalyzed ketone Suzuki-Miyaura coupling reaction of benzylacetone with arylboronic acid is developed. Selective C(O)-C bond activation, which employs aminopyridine as a temporary directing group and ethyl vinyl ketone as a hydride acceptor, occurs on the alkyl chain containing a β-position hydrogen. A series of acetophenone products were obtained in yields up to 75%.
- Zhong, Jing,Zhou, Wuxin,Yan, Xufei,Xia, Ying,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 1372 - 1377
(2022/02/23)
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- Photoinduced Acetylation of Anilines under Aqueous and Catalyst-Free Conditions
-
A green and efficient visible-light induced functionalization of anilines under mild conditions has been reported. Utilizing nontoxic, cost-effective, and water-soluble diacetyl as photosensitizer and acetylating reagent, and water as the solvent, a variety of anilines were converted into the corresponding aryl ketones, iodides, and bromides. With advantages of environmentally friendly conditions, simple operation, broad substrate scope, and functional group tolerance, this reaction represents a valuable method in organic synthesis.
- Yang, Yu-Ming,Yan, Wei,Hu, Han-Wei,Luo, Yimin,Tang, Zhen-Yu,Luo, Zhuangzhu
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p. 12344 - 12353
(2021/09/02)
-
- 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
-
supporting information
p. 5625 - 5638
(2020/08/21)
-
- Metal-Free Photoinduced Transformation of Aryl Halides and Diketones into Aryl Ketones
-
The acylation of aryl halides to prepare aryl ketones without metal catalyst represents an important yet challenging topic towards more sustainable ketone synthesis. Herein, we describe a simple and efficient metal-free protocol for the acylation of aryl halides with diketone under the irradiation of light utilizing N-methylpiperidine as base under an air atmosphere. This reaction can tolerate a wide range of functional groups and the corresponding ketones can be obtained in modest to good yields.
- Yao, Qiuli,Liu, Wenbo,Liu, Peng,Ren, Linjing,Fang, Xuehong,Li, Chao-Jun
-
supporting information
p. 2721 - 2724
(2019/01/14)
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- P -Selective (sp2)-C-H functionalization for an acylation/alkylation reaction using organic photoredox catalysis
-
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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- Zeolite y nanoparticle assemblies with high activity in the direct hydration of terminal alkynes
-
A strong acidic zeolite Y nanoparticle assembly (HNANO-Y) with a micro-meso-macroporous structure was synthesized and used as a highly efficient heterogeneous catalyst for the hydration of alkynes to prepare ketone compounds, as compared to acidic mesoporous zeolite ZSM-5 and Beta catalysts. This feature should be assigned to the fact that the micro-meso-macroporous structure in the HNANO-Y benefits mass transfer and the strongly acidic sites on HNANO-Y facilitate alkyne hydration activity. The catalyst can be reused six times without loss of activity.
- Xu, Shuling,Yun, Zhi,Feng, Yu,Tang, Ting,Fang, Zhongxue,Tang, Tiandi
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p. 69822 - 69827
(2016/08/06)
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- The micro-flow field reactor Friedel-Crafts application of the catalyst in the reaction
-
The invention discloses an application of a micro-flow field reactor in Friedel-Crafts reaction. An immobilized microchannel reactor is filled with nano iron oxide particles for catalysis of Friedel-Crafts acylation reaction of aromatic hydrocarbon and acetyl chloride, wherein the nano iron oxide particles are prepared by the following methods: dissolving an iron-containing inorganic matter with distilled water, respectively and simultaneously pumping a water solution of inorganic alkali and a water solution of the iron-containing inorganic matter into the immobilized microchannel reaction device; standing for 30 seconds to 1 minute, reacting at a room temperature, and centrifuging the reaction product; and washing and drying sediments, and then sintering in a muffle furnace at 500 DEG C for 2 hours. The immobilized microchannel reactor is filled with the nano iron oxide particles prepared by the method for catalysis of Friedel-Crafts acylation reaction of the aromatic hydrocarbon and acetyl chloride.
- -
-
Paragraph 0056-0060
(2017/02/24)
-
- METHOD OF ACYLATING AN AROMATIC COMPOUND
-
The present invention relates to a method of acylating a substituted aromatic compound. The substituted aromatic compound is reacted with an acylating agent in the presence of a macroreticular sulfonic acid ion exchange resin having a water-to-phenol shrinkage between 25 % and 40 %. The method is very advantageous in that the resin is deactivated much less than other resins without a fast drop in conversion and selectivity in the reaction.
- -
-
Page/Page column 18; 19
(2015/01/16)
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- 5-Aryl-1H-pyrazole-3-carboxylic acids as selective inhibitors of human carbonic anhydrases IX and XII
-
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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- N-Functionalized Amino Acids Promoted Aerobic Copper-Catalyzed Oxidation of Benzylic Alcohols in Water
-
Instead of traditional N,N-bidentate ligands, N-functionlized amino acids were used as powerful N,O-bidentate ligands in aerobic copper/TEMPO-catalyzed system for promoting oxidation of benzylic alcohols. Under the optimized reaction conditions, a wide range of primary and secondary benzylic alcohols have been efficiently converted into aldehydes and ketones with good to excellent yields in water.
- Zhang, Guofu,Lei, Jie,Han, Xingwang,Luan, Yuxin,Ding, Chengrong,Shan, Shang
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p. 779 - 784
(2015/03/30)
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- Sustainable flow oppenauer oxidation of secondary benzylic alcohols with a heterogeneous zirconia catalyst
-
A flow chemistry process for the Oppenauer oxidation of benzylic secondary alcohols using partially hydrated zirconium oxide and a simple carbonyl containing oxidant such as acetone, cyclohexanone, and neopentanal is reported. The heterogeneous oxidative system could be applied to a wide range of functionalized alcohol substrates, allowing clean and fast delivery of ketone products within a few minutes between 40 and 100 C.
- Chorghade, Rajeev,Battilocchio, Claudio,Hawkins, Joel M.,Ley, Steven V.
-
supporting information
p. 5698 - 5701
(2013/12/04)
-
- In situ generation of active species "nO" for the aerobic oxidative deprotection of aldoximes catalyzed by FeCl3/TEMPO
-
A simple and efficient aerobic oxidative deoximation system, using molecular oxygen as the green oxidant and FeCl3/TEMPO as the catalyst, is developed for a wide range of aldoximes. Notably, nitric oxide (NO), an active species for aerobic oxidation reactions, is assumed to be generated in situ from the cleavage of oximes and further confirmed by the existence of a large quantity of NO3- by Ionic Chromatography (IC).
- Zhang, Guofu,Wen, Xin,Wang, Yong,Han, Xingwang,Luan, Yuxin,Zheng, Lebin,Ding, Chengrong,Cao, Xiaoji
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p. 22918 - 22921
(2013/11/19)
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- Highly selective Wacker reaction of styrene derivatives: A green and efficient aerobic oxidative process promoted by benzoquinone/NaNO 2/HClO4 under mild conditions
-
A green and efficient catalytic redox system for the aerobic oxidative Wacker oxidation of styrene derivatives at room temperature using molecular oxygen as the terminal oxidant without copper chloride has been developed. The newly developed system exhibited excellent catalytic activity for the smooth transformation of terminal styrene derivatives to the desired methyl ketones with up to 96% yield and >99% selectivity. The Royal Society of Chemistry 2013.
- Zhang, Guofu,Xie, Xiaoqiang,Wang, Yong,Wen, Xin,Zhao, Yun,Ding, Chengrong
-
supporting information
p. 2947 - 2950
(2013/07/25)
-
- Nano-sulfated titania (TiO2/SO2-4) as a new solid acid catalyst for Friedel-Crafts acylation and Beckman rearrangement in solvent-free conditions
-
The present work describes a novel application of nano-sulfated titania (nano-ST) as a solid acid catalyst for Friedel-Crafts acylation and Beckmann rearrangement. A nano-ST catalyst has been synthesized and characterized using various techniques such as XRD, scanning electron morphology, transmission electron microscopy, FT-IR, measurement of the specific surface area by Brunauer-Emmett-Teller theory and thermal analysis. The influences of various reaction parameters such as reaction temperature, molar ratio of reactants, reaction time and solvent effects have been investigated. [image omitted].
- Hosseini-Sarvari, Mona,Safary, Ensieh
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experimental part
p. 463 - 473
(2012/06/16)
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- Convenient method for the Friedel-Crafts acylation of benzene derivatives using silver nitrate as catalyst
-
(Chemical Equation Presented) Friedel-Crafts acylation of benzene derivatives such as anisole, toluene, and xylene has been successively carried out using silver nitrate as the catalyst in the presence of an eco friendly solvent (ethyl alcohol). Both benzoyl chloride and acetyl chloride reacted smoothly under the conditions to afford the corresponding ketones in good yield. Copyright Taylor & Francis Group, LLC.
- Rai, K.M. Lokanatha,Musad, Ebraheem Abdu,Jagadish,Shivakumar
-
experimental part
p. 953 - 955
(2011/04/23)
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- Polystyrene supported Al(OTf)3: An environmentally friendly heterogeneous catalyst for Friedel-Crafts acylation of aromatic compounds
-
Stable and non-hygroscopic polystyrene supported aluminium triflate (Ps-Al(OTf)3), which is prepared easily from cheap and commercially available compounds was found to be an environmentally friendly heterogeneous catalyst for Friedel-Crafts acylation of arenes using acid chlorides in the absence of solvent under mild reaction conditions. The catalyst can be reused up to five times after simple washing with dichloromethane.
- Boroujeni, Kaveh Parvanak
-
experimental part
p. 3156 - 3158
(2012/05/20)
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- Catalytic Friedel-Crafts acylation and benzoylation of aromatic compounds using activated hematite as a novel heterogeneous catalyst
-
Catalytic Friedel-Crafts acylation of benzene and unactivated benzenes such as chlorobenzene and nitrobenzene have been successfully carried out using activated hematite (α-Fe2O3) as a new, heterogeneous and green catalyst. Sonication of neat α-Fe2O3 in a water bath under air atmosphere at room temperature followed by heating at 200°C, dramatically increase the activity of α-Fe2O 3. With the catalyst loading as low as 5.0mol%, a wide variety of benzene derivatives were easily converted into the corresponding acylated products in a clean and high-yielding acylation reaction. It was found that the activated α-Fe2O3 could be efficiently recycled and reused several times by simple washing with ethyl acetate, this cannot be attained with most of the traditional catalysts. Copyright
- Sharghi, Hashem,Jokar, Mahboubeh,Doroodmand, Mohammad Mahdi,Khalifeh, Reza
-
experimental part
p. 3031 - 3044
(2011/02/21)
-
- Silica gel supported AlCl3 catalyzed Friedel-Crafts acylation of aromatic compounds
-
Silica gel supported aluminium trichloride (SiO2-AlCl3) has been shown to be a mild, efficient, and chemoselective heterogeneous Lewis acid catalyst for the acylation of aromatic compounds with acid chlorides. The catalyst can be reused up to five times after simple washing with ether and is stable (as a bench top catalyst).
- Boroujeni, Kaveh Parvanak
-
experimental part
p. 1395 - 1398
(2011/10/09)
-
- Electrochemically promoted Friedel-Crafts acylation of aromatic compounds
-
Friedel-Crafts acylation is carried out with several aromatic substrates in the presence of an electrochemically active aluminium anode to minimize the inorganic reagents. Only a catalytic amount of AlCl3 (5 mol %) is required to enable the anodic polarization of the aluminium electrode to promote continuous acylation. This process typically gave products in good yields (70-96%).
- Karthik,Kulangiappar,Marken, Frank,Kulandainathan, M. Anbu
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p. 2625 - 2627
(2008/09/18)
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- Selective one-pot synthesis of various phenols from diarylethanes
-
Various substituted phenols were selectively synthesized by a one-pot reaction through the NHPI-catalyzed aerobic oxidation of 1,1-diarylethanes followed by treatment with dilute sulfuric acid. The Royal Society of Chemistry.
- Nakamura, Ryota,Obora, Yasushi,Ishii, Yasutaka
-
supporting information; experimental part
p. 3417 - 3419
(2009/02/05)
-
- Process for the preparation of substituted phenols
-
A substituted phenolic compound is prepared by oxidizing a substituted diarylethane compound with oxygen in the presence of a nitrogen-containing cyclic compound, and treating the oxidized product with an acid. The nitrogen-containing cyclic compound includes, as a constituent of its ring, a skeleton represented by following Formula (I): wherein X is oxygen atom or an -OR group, where R is hydrogen atom or a hydroxyl-protecting group. The substituted diarylethane compound is represented by following Formula (1): wherein each of Ring Ar1 and Ring Ar2 is independently a monocyclic or polycyclic aromatic carbocyclic ring; Y1 is an electron-donating group; Y2 is an electron-withdrawing group; "p" is an integer of 1 or more; and "q" is an integer of 0 or more. The substituted phenolic compound is represented by following Formula (2): wherein Ring Ar1, Y1, and "p" are as defined above.
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Page/Page column 14
(2008/12/08)
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- Solvent-free catalytic Friedel - Crafts acylation of aromatic compounds with carboxylic acids by using a novel heterogeneous catalyst system: p-Toluenesulfonic acid/graphite
-
TsOH/graphite was found to be an effective catalyst system for the Friedel-Crafts acylation of aromatic compounds with carboxylic acids. Both aliphatic and aromatic carboxylic acids reacted smoothly under TsOH/graphite catalysis to afford the corresponding aromatic ketones in high yields. The graphite was easily recovered by simple extraction and could be reused without decrease of activity in the presence of fresh TsOH.
- Sarvari, Mona Hosseini,Sharghi, Hashem
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p. 2282 - 2287
(2007/10/03)
-
- Antimony(V) chloride-benzyltriethylammonium chloride complex as an efficient catalyst for friedel-crafts acylation reactions
-
A novel catalytic system, the complex of antimony(V) chloride (SbCl 5) and benzyltriethylammonium chloride (TEBA), C6H 5CH2NEt3(SbCl5)2Cl complex, is described for Friedel-Crafts acylation reactions of aromatics with acyl and sulfonyl chlorides. The catalyst has a number of useful characteristics, such as ready access, minimal toxicity, reusability, insensitivity to atmosphere and moisture, rapid acylation with high yield, and ease of operation.
- Huang, An-Ping,Liu, Xue-Yuan,Li, Lian-Hua,Wu, Xiao-Li,Liu, Wei-Min,Liang, Yong-Min
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p. 599 - 602
(2007/10/03)
-
- 2-Hydroxymethyl-4-[5-(4-methoxyphenyl)-3-trifluoromethyl-1H-1-pyrazolyl] -1-benzenesulfonamide (DRF-4367): An orally active COX-2 inhibitor identified through pharmacophoric modulation
-
Analogs of 1,5-diarylpyrazoles with a novel pharmacophore at N1 were designed, synthesized and evaluated for the in-vitro cyclooxygenase (COX-1/COX-2) inhibitory activity. The variations at/around position-4 of the C-5 phenyl ring in conjunction with a CF3 and CHF2 groups at C-3 exhibited a high degree of potency and selectivity index (SI) for COX-2 inhibition. The in-vivo evaluation of these potent compounds with a few earlier ones indicated the 4-OMe-phenyl analog 6 and the 4-NHMe-phenyl analog 9 with a CF3, and the 4-OEt-phenyl analog 19 with a CHF2 group at C-3 to possess superior potency than celecoxib. In addition to its impressive anti-inflammatory, antipyretic, analgesic and anti-arthritic properties, compound 6 (DRF-4367) was found to possess an excellent pharmacokinetic profile, gastrointestinal (GI) safety in the long-term arthritis study and COX-2 potency in human whole blood assay. Thus, compound 6 was selected as an orally active anti-inflammatory candidate for pre-clinical evaluation.
- Singh, Sunil Kumar,Vobbalareddy, Saibaba,Kalleda, Srinivasa Rao,Rajjak, Shaikh Abdul,Casturi, Seshagiri Rao,Datla, Srinivasa Raju,Mamidi, Rao N.V.S.,Mullangi, Ramesh,Bhamidipati, Ravikanth,Ramanujam, Rajagopalan,Akella, Venkateswarlu,Yeleswarapu, Koteswar Rao
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p. 2442 - 2450
(2007/10/03)
-
- Zinc Mediated Friedel-Crafts Acylation in Solvent-Free Conditions under Microwave Irradiation
-
Zn powder is found to catalyze the Friedel-Crafts acylation of aromatic compounds with acyl halides efficiently under microwave irradiation in solvent-free conditions. Activated substrates undergo acylation predominantly at the para-position. The Zn powder can be re-used up to six times after simple washing with diethyl ether and dilute HCl.
- Paul, Satya,Nanda, Puja,Gupta, Rajive,Loupy, Andre
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p. 2877 - 2881
(2007/10/03)
-
- LiClO4-acyl anhydrides complexes as powerful acylating reagents of aromatic compounds in solvent free conditions
-
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)
-
- Regeneration of ketones from oximes in dry media under microwave irradiation
-
Regeneration of ketones from oximes have been achieved using HCOOH/SiO2 as solid support catalyst in dry media under microwave irradiation with 86~94% yield.
- Zhou, Jian-Feng,Tu, Shu-Jiang,Feng, Jun-Cai
-
p. 959 - 962
(2007/10/03)
-
- Environmentally safe and facile solid state regeneration of carbonyl compounds from oximes by silica supported MnO2 under microwave irradiation
-
We report here an efficient and convenient method for solvent free 'dry' state conversion of oximes to corresponding carbonyl compounds using silica supported MnO2, under microwave irradiation. The deoximation was tested for at least twelve runs with just air drying the reagent after each run and with reproducible yields.
- Khadilkar, Bhushan M.,Madyar, Virendra R.
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p. 1081 - 1082
(2007/10/03)
-
- Studies in Beckmann rearrangement of substituted benzophenone and acetophenone oximes
-
The Beckmann rearrangement of substituted benzophenone and acetophenone oximes was effected using 'silferc' as catalyst, prepared by impregnating anhydrous FeCl3 on silica gel by co-grinding technique.
- Khadilkar, Bhushan M.,Upadhyaya, Dharita J.
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p. 1867 - 1873
(2007/10/03)
-
- Practical synthesis of acetophenones from phenoltriflates
-
A new practical method for the preparation of acetophenone from aryl triflates is reported. The acyl group is installed by a mixture of SnMe4, Pd(0) and CO (balloon), using a three-component procedure.
- Garrido, Fabrice,Raeppel, Stéphane,Mann, André,Lautens, Mark
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p. 265 - 266
(2007/10/03)
-
- Friedel-crafts reactions catalyzed by rare earth metal trifluoromethanesulfonates
-
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
-
p. 2325 - 2333
(2007/10/03)
-
- Acid-mediated specific α,α-diarylation and α-monoarylation reactions of pyruvic acid with/without decarbonylation
-
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
-
p. 1687 - 1695
(2007/10/03)
-
- Toward a clean alternative to Friedel-Crafts acylation: In situ formation, observation, and reaction of an acyl bis(trifluoroacetyl)phosphate and related structures
-
Reaction of acyl trifluoroacetates with phosphoric acid in the presence of trifluoroacetic anhydride (TFAA) leads to the ready formation of acyl bis(trifluoroacetyl)phosphates, which are powerful acylating agents. Formation of these species and the subsequent acylation reaction are carried out, without added solvent, in a single in situ reaction process. In this reaction system, anisole is rapidly acylated at ambient temperature using a variety of carboxylic acids giving the para isomer exclusively. TFAA acts as an activating agent and can be recovered from the reaction system as trifluoroacetic acid (TFA) and converted back to TFAA using a dehydrating agent, while phosphoric acid behaves as a covalent catalyst in the process. This reaction system has many features which are required elements of a clean alternative to the Friedel-Crafts process.
- Smyth, Timothy P.,Corby, Brian W.
-
p. 8946 - 8951
(2007/10/03)
-
- Ln(OTf)3-LiClO4 as reusable catalyst system for Friedel-Crafts acylation
-
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
-
p. 183 - 184
(2007/10/03)
-
- Catalytic Friedel-Crafts Acylation Reactions Using Hafnium Triflate as a Catalyst in Lithium Perchlorate-Nitromethane
-
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
-
p. 409 - 412
(2007/10/02)
-
- Hafnium(IV)Trifluoromethanesulfonate, An Efficient Catalyst for the Friedel-Crafts Acylation and Alkylation Reactions
-
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
-
p. 2053 - 2060
(2007/10/02)
-
- Methyl Group Effect on the Proton Affinity of Methylated Acetophenones Studied by Two Mass Spectrometric Techniques
-
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)
-
- Excited State Selectivity in the Thermolysis of a 3,4-Diaryl-3,4-dimethyl-1,2-dioxetane
-
Total efficiencies for the production of triplet ketones from cis- and trans-3-(3,4-dimethylphenyl)-4-phenyl-1,2-dioxetane (11) are 14.1 +/- 0.2 percent and 21.3 +/- 0.5percent, respectively.The specific efficiency for the production of triplet acetophenone from trans-11 was determined to be 19 +/- 4 percent by trapping the triplet with 2-methyl-2-butene to give the oxetane.These results show that the production of triplets from the dioxetane is state selective, since the n,?* acetophenone triplet is higher in energy than the alternative ?,?* triplet of 3,4-dimethylacetophenone.This state-selective production of triplet ketone is most reasonably dictated by orbital symmetry control in the thermolysis of the dioxetane.With this assumption, implications on the mechanism of dioxetane decomposition in terms of biradical intermediates or a concerted biradicaloid process are considered.Activation parameters for thermolysis of cis- and trans-11 are consistent with a biradical or biradicaloid mechanism.From these activation parameters and molecular mechanics calculations, it was concluded that the transition state was not quite half-way between the dioxetane reactant and a biradical intermediate, if the reaction proceeded through a biradical intermediate.In conjunction with earlier reported triplet efficiencies of 3,4-diaryl-3,4-dimethyl-1,2-dioxetanes and the efficiencies of cis- and trans-11, the participation of a triplet exciplex was suggested.
- Richardson, William H.,Batinica, Greg,Janota-Perret, Kasia,Miller, Todd,Shen, Dongming
-
p. 6140 - 6144
(2007/10/02)
-
- β-Phenylsulfonylenones as α,β-acetylenic ketones equivalents in Diels-Alder reactions
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(E)-β-phenylsulfonylenones, readily prepared by oxidation of the alcohols, react with a wide variety of dienes in the presence of activated silica gel. The basic elimination of the phenylsulfonyl group in the resulting adducts gives high yields of the corresponding enones, thus showing the usefulness of these dienophiles as reactive synthetic equivalents of α,β-acetylenic ketones.
- Leon,Carretero
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p. 5405 - 5408
(2007/10/02)
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- 188. Addition of Carbon Nucleophiles to Tricarbonylchromium Complexes of 1,2-Dihydrocyclobutabenzene, Indane, 1,2,3,4-Tetrahydronaphthalene and ortho-Xylene
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3-Substituted 1,2-dihydrocyclobutabenzenes (bicycloocta-1,3,5-triene) are readily accessible from (1) via a two-step sequence which involves addition of a nucleophile and oxidation of the intermediate anionic
- Kuendig, E. Peter,Grivet, Chantal,Wenger, Eric,Bernardinelli, Gerald,Williams, Alan F.
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p. 2009 - 2023
(2007/10/02)
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- Retinobenzoic acids. 3. Structure-activity relationships of retinoidal azobenzene-4-carboxylic acids and stilbene-4-carboxylic acids
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Alkyl-substituted azobenzene-4-carboxylic acids are potent differentiation inducers of human promyelocytic leukemia cell line HL-60 to mature granulocytes. Their structure-activity relationships are very similar to those of other retinoidal benzoic acids which are generally represented by 4 and named retinobenzoic acids. The structure-activity relationships of azobenzenecarboxylic acids can also be applied to the known retinoid TTNPB (3). Thus, (E)-4-[2-(3,4-diisopropylphenyl)-1-propenyl]benzoic acid (St30 (28)), and (E)-4-[2-(3-tert-butylphenyl)ethenyl]benzoic acid (St40) (29)), the acyclic alkyl analogues of TTNPB, are nearly as active as retinoic acid. Among the oxidatively derived compounds (Az90, Ep series and Ox series) of azobenzene- or stilbenecarboxylic acids, Az90 (71) and Ep80 (61) have strong activities. However, all the bishydroxylated derivatives of TTNPB are inactive, while a diketo analogue Ox580 (69) has only weak potency. The activities of conformationally restricted compounds of TTNPB offer some information on the stereochemistry of the active form of these retinoidal compounds.
- Kagechika,Himi,Namikawa,Kawachi,Hashimoto,Shudo
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p. 1098 - 1108
(2007/10/02)
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- Substituent Effects upon Efficiency of Excited-State Acetophenones Produced on Thermolysis of 3,4-Diaryl-3,4-dimethyl-1,2-dioxetanes
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The effects of meta and para substituents upon the triplet (αT) and singlet (αS) efficiencies in the thermolysis of 3,4-diaryl-3,4-dimethyl-1,2-dioxetanes 3, 3-aryl-3,4,4-trimethyl-1,2-dioxetanes 4, and 3-aryl-3-(bromomethyl)-4,4-dimethyl-1,2-dioxetanes 5 are reported.Triplet efficiencies for series 3 dioxetanes, where the two proketone moieties are identical, are sensitive to aryl substituent changes.Attempted correlation of log αT with Hammett-type substituents constants failed, and the best correlation of log αT was with the lowest triplet energy of the acetophenones T) = (0.77+/-0.19)ET1(ArCOCH3)-55.05+/-14.00, r=0.834, Sy*x=+/-0.336>.This type of correlation was previously observed with 3-aryl-3-methyl- and 3-aryl-3-methyl-3,3-(2,2'-biphenyldiyl)-1,2-dioxetanes, where the slopes (S values) are 0.38+/-0.14 and 0.52+/-0.08, respectively.In these two dioxetane series, the triplet energies of the companion proketones (formaldehyde and fluorenone) to ArCOCH3 are approximately equal to and less than ET1(ArCOCH3).For the 4 and 5 series dioxetanes, there was no change in triplet efficiency with various aryl substituents, where the average αT values are 29.1+/-2.4percent for 4 and 28.1+/- 0.7percent for 5.For these two dioxetane series, the triplet energy of the companion proketone (acetone) is higher than ET1(ArCOCH3).With regard to triplet efficiencies, all of these dioxetane series fall into two categories: (i) where the companion proketones possess triplet energies approximately equal to or less than ET1(ArCOCH3) and where αT is dependent upon substituent changes in the ArCOCH3 moiety; (ii) where the companion proketone possesses a triplet energy higher than ET1(ArCOCH3) and αT is independent of substitution changes in the ArCOCH3 moiety.An exciplex or encounter complex process is proposed to explain the apparent communication between the two proketone moieties in category i dioxetanes.Activation parameters for series 3-5 were typical of most other tetrasubstituted dioxetanes.The ρ values for ?+ correlations of series 3 and 4 plus 5 dioxetanes are -0.285 +/- 0.033 and -0.20 +/- 0.05, respectively, which is consistent with a 1,4-dioxy biradical decomposition process.
- Richardson, William H.,Stiggal-Estberg, Diana L.,Chen, Zhangping,Baker, John C.,Burns, David M.,Sherman, David G.
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p. 3143 - 3150
(2007/10/02)
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- FACTORS IN THE CONTROL OF PRODUCT COMPOSITION IN THE REACTIONS OF TRIALKYL PHOSPHITES WITH α-HALOGENOACETOPHENONES IN ALCOHOLIC MEDIA
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α-Hydroxyphosphonates are formed, in addition to vinyl phosphates and dehalogenated ketones, in the reactions of trimethyl phosphite (in methanol) or triethyl phosphite (in ethanol) with variously substituted α-chloro, α-bromo, and α,α-dichloro-acetophenones.Tri-isopropyl phosphite in propan-2-ol gives only the vinyl phosphate.Ketophosphonates are not detectable amongst the reaction products under the conditions used.Trends in product composition can be correlated with the leaving ability of halogen, substituent effects, structure of the phosphite, and reaction temperature.Additional products are obtained in the reactions of trimethyl phosphite in methanol with 4-nitro-α-chloroacetophenone, which gives the dehalogenated hydroxyphosphonate, and with the α,α-dichloroacetophenones which undergo monodehalogenation.Twenty three new α-hydroxyphosphonates are reported.
- Keglevich, Gyoergy,Petnehazy, Imre,Toeke, Laszlo
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p. 341 - 350
(2007/10/02)
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- THE PHENYLCARBENE REARRANGEMENT REVISITED
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The evolution of mechanistic ideas about the phenylcarbene rearrangement has been reviewed, and three closely linked problems have been identified toward whose solution this research has been aimed: 1.Why do the ratios of the stable end products from the rearrangements of o-, m- and p-tolylmethylene differ when all three reactions have been thought to pass through a common intermediate? 2.Why does the rearrangement of 2-methylcycloheptatrienylidene lead to exclusive formation of styrene? 3.What is the mechanism of styrene formation from o-tolylmethylene? New mechanisms have been proposed in which m- and p-tolylmethylene can rearrange to styrene without necessarily being converted to o-tolylmethylene.The formation of a small amount of 2,6-dimethylstyrene from the rearrangement of 3,4,5-trimethylphenylmethylene is viewed as evidence for such a mechanism, and a set of interconverting norcaradienylidenes are believed to be the crucial intermediates.Other alternatives are considered and rejected on the basis of the rearrangement products of 3,5-dimethyl- and 3,4,5-trimethylphenylmethylene.
- Gaspar, Peter P.,Hsu, Jong-Pyng,Chari, Sarangan,Jones, Maitland Jr.
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p. 1479 - 1508
(2007/10/02)
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- Substituent Effects on Exited-State Efficiencies: Thermolysis of 3,3-(2,2'-Biphenyldiyl)-4-methyl-4-aryl-1,2-dioxetanes
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Triplet and singlet ketone efficiencies was determined for the thermolysis of a series of nine 3,3-(2,2'-biphenyldiyl)-4-methyl-4-aryl-1,2-dioxetanes, where substituent changes were made in the para and meta positions of the aryl group.Triplet efficiencies (αT), which were determined by trans-stilbene isomerization, ranged from 2.0percent (Ar=p-BrC6H4) to 19.0percent (Ar=C6H5) and the best linear free energy correlation was with ET1(ArCOCH3):log percent αT=(0.518 +/- 0.079)ET1(ArCOCH3)-36.62 +/- 5.73, Sy*x = +/- 0.144, which corresponds to +/- 1.4percent in percent αT.Since no light enhancement resulted upon addition of 9,10-dibromoanthracene, it was concluded that the intercepted triplet ketone product was fluorenone.The results were considered in terms of a triplet ketone exciplex (Scheme I) and equilibrating solvent caged encounter complexes (Scheme II).The singlet efficiencies for all members in the series were essentially constant (percentαS1 = 0.17percent).The chemiluminescent (CL) emission spectra of dioxetanes, where Ar = C6H5 and m-BrC6H4, match the fluorescence spectrum of fluorenone.In addition, the CL emission is not enhanced upon nitrogen purging.From a consideration of activation parameters and ρ reaction constants, a 1,4-dioxy biradical decomposition route for these dioxetanes appears most likely.
- Richardson, William H.,Thomson, Stephen A.
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p. 1803 - 1810
(2007/10/02)
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