- A general approach to intermolecular carbonylation of arene C-H bonds to ketones through catalytic aroyl triflate formation
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The development of metal-catalysed methods to functionalize inert C-H bonds has become a dominant research theme in the past decade as an approach to efficient synthesis. However, the incorporation of carbon monoxide into such reactions to form valuable ketones has to date proved a challenge, despite its potential as a straightforward and green alternative to Friedel-Crafts reactions. Here we describe a new approach to palladium-catalysed C-H bond functionalization in which carbon monoxide is used to drive the generation of high-energy electrophiles. This offers a method to couple the useful features of metal-catalysed C-H functionalization (stable and available reagents) and electrophilic acylations (broad scope and selectivity), and synthesize ketones simply from aryl iodides, CO and arenes. Notably, the reaction proceeds in an intermolecular fashion, without directing groups and at very low palladium-catalyst loadings. Mechanistic studies show that the reaction proceeds through the catalytic build-up of potent aroyl triflate electrophiles.
- Kinney, R. Garrison,Tjutrins, Jevgenijs,Torres, Gerardo M.,Liu, Nina Jiabao,Kulkarni, Omkar,Arndtsen, Bruce A.
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p. 193 - 199
(2018/02/06)
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- Controlled photo-flow oxidative reaction (UV-FOR) platform for ultra-fast phthalide and API synthesis
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An integrated photo-flow oxidative reaction (UV-FOR) platform approach is presented for the synthesis of phthalides. The current protocol is catalyst-free, and uses economical and abundant hydro-carbons and hydrocarbon derivatives such as benzoic acid, benzene, and xylene, as starting materials. The reaction is performed using oxygen as a green oxidant in a time- and labour-efficient manner. This integrated approach has been shown to be successful in making a UV-FOR platform suitable for the on-demand synthesis of phthalides and their further syntheses to 2-arylmethylbenzoic acids and arylogous Michael addition products under relatively mild conditions. The current protocol was further extended to the gram scale synthesis of an ischemic stroke-relevant active pharmaceutical ingredient (API), 3-N-butylphthalide (NBP), in a continuous flow process.
- Aand, Dnyaneshwar,Karekar, Sanjeev,Mahajan, Bhushan,Pawar, Amit B.,Singh, Ajay K.
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p. 4584 - 4590
(2018/10/23)
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- Co(III)-Catalyzed Synthesis of Quinazolines via C-H Activation of N-Sulfinylimines and Benzimidates
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C-H activation of arenes has been established as an important strategy for heterocycle synthesis via annulations between arenes and unsaturated coupling partners. However, nitriles failed to act as such a coupling partner. Dioxazolones have been employed as a synthon of nitriles, and subsequent coupling with arenes such as N-sulfinylimines and benzimidates bearing a functionalizable directing group provided facile access to two classes of quinazolines under Co(III)-catalysis.
- Wang, Fen,Wang, He,Wang, Qiang,Yu, Songjie,Li, Xingwei
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supporting information
p. 1306 - 1309
(2016/04/01)
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- Catalytic Friedel-Crafts acylation: Magnetic nanopowder CuFe 2O4 as an efficient and magnetically separable catalyst
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Catalytic regioselective Friedel-Crafts acylation of an array of anisoles/arenes with various acid chlorides using 5-20 mol % of magnetic nanopowder CuFe2O4 is reported. Unlike the conventional Friedel-Crafts reactions, which are catalyzed by moisture sensitive homogeneous catalysts/promoters, the nanopowder CuFe2O4 catalyst is moisture insensitive and the product/ketone-catalyst isolation is easily achieved using the magnetic properties of CuFe2O4.
- Parella, Ramarao,Naveen,Kumar, Amit,Babu, Srinivasarao Arulananda
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p. 1738 - 1742
(2013/03/28)
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- Design, synthesis and characterization of self-assembled As 2L3 and Sb2L3 cryptands
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The syntheses and X-ray crystal structures of six new self-assembled supramolecular As and Sb-containing cryptands are described. Analysis in the context of previously reported As2L3 and Sb 2L3 cryptands reveals that small differences in ligand geometries result in significant differences in the helicity of the complexes and the stereochemistry of the metal coordination within the assembled complexes. Additionally, a new synthetic route is described which involves exposure of reactants to vacuum to help facilitate self-assembly.
- Fontenot, Sean A.,Cangelosi, Virginia M.,Pitt, Melanie A. W.,Sather, Aaron C.,Zakharov, Lev N.,Berryman, Orion B.,Johnson, Darren W.
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supporting information; experimental part
p. 12125 - 12131
(2012/03/11)
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- MoO2Cl2 as a novel catalyst for Friedel-Crafts acylation and sulfonylation
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The use of MoO2Cl2 as a novel catalyst for Friedel-Crafts acylation and sulfonylation is described. A series of aromatic ketones and sulfones were prepared in moderate to good yields using acyl chloride or sulfonyl chloride in the presence of MoO2Cl2 (20 mol %), under solvent-free conditions.
- de Noronha, Rita G.,Fernandes, Ana C.,Rom?o, Carlos C.
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experimental part
p. 1407 - 1410
(2009/06/18)
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- Esters as acylating reagent in a Friedel-Crafts reaction: Indium tribromide catalyzed acylation of arenes using dimethylchlorosilane
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(Chemical Equation Presented) The Friedel-Crafts acylation of arenes with esters by dimethylchlorosilane and 10 mol % of indium tribromide has been achieved. The key intermediate RCOOSi(Cl)Me2 is generated from alkoxy esters with the evolution of the corresponding alkanes. The scope of the alkoxy ester moiety was wide: tert-butyl, benzyl, allyl, and isopropyl esters were successful. In addition, we demonstrated the direct synthesis of the indanone intermediate 11 of salviasperanol from ester 10.
- Nishimoto, Yoshihiro,Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 9465 - 9468
(2009/04/06)
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- Friedel-Crafts acylation reaction using carboxylic acids as acylating agents
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Dehydrative Friedel-Crafts acylation reaction of aromatic compounds with carboxylic acids as acylating agents was investigated in the presence of Lewis acid- or Br?nsted acid-catalyst. Various metal triflates and bis(trifluoromethanesulfonyl)amides showed catalytic activity at high temperature, among which Eu(NTf2)3 proved to be the most effective and efficiently catalyzed the acylation reaction of alkyl- and alkoxybenzenes with aliphatic and aromatic carboxylic acids at 250 °C. Bi(NTf2)3 was more effective than Eu(NTf2)3 at lower temperature, but proved to be hydrolyzed in the presence of a small amount of water to give HNTf2 and [Bi6O4(OH)4(H2O)6](NTf2)6. The structure of the latter compound was confirmed by a single crystal X-ray analysis. Among five Br?nsted acids, HOTf, HNTf2, HCTf3, TsOH, and Nafion SAC-13, HNTf2 has proved to be the most efficient catalyst and more effective than Eu(NTf2)3 for the acylation of p-xylene with heptanoic acid at 220 °C or lower temperature. HNTf2 catalyzed the acylation of anisole with carboxylic acids in high yields in refluxing toluene with azeotropic removal of water.
- Kawamura, Masato,Cui, Dong-Mei,Shimada, Shigeru
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p. 9201 - 9209
(2007/10/03)
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- Lewis acid-catalyzed Friedel-Crafts acylation reaction using carboxylic acids as acylating agents
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Rare-earth metal Lewis acids, in particular Eu(NTf2) 3, were found to be efficient catalysts for Friedel-Crafts acylation reaction using aliphatic as well as aromatic carboxylic acids as acylating agents at high temperature.
- Kawamura, Masato,Cui, Dong-Mei,Hayashi, Teruyuki,Shimada, Shigeru
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p. 7715 - 7717
(2007/10/03)
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- OXIDATIVE CHLORINATION OF AROMATIC COMPOUNDS IN THE PRESENCE OF NITROGEN-CONTAINING OXIDIZING AGENTS
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Mixture of the chlorides and nitrates of alkali metals in aqueous trifluoroacetic acid can be used for the selective oxidative chlorination of benzene, halogenobenzenes, toluene, and p-toluic acid with preparative yields.By variation of the water content of the solvent and the nitrate-chloride ratio it is possible to suppress the nitration side reaction.In the presence of oxygen or air alkali-metal nitrites can also be used as oxidizing agents in this process.The chlorinating agent in these systems is molecular chlorine, as confirmed by a comparative study of the reactions of two groups of potential chlorinating agents (nitrosyl chloride and nitryl chloride) under these conditions.The reactions of naphthalene and polymethylbenzenes with nitrosyl chloride in trifluoroacetic acid, leading to the products from chlorination and dehydrooligomerization of the aromatic substrates, were also studied.
- Makhon'kov, D. I.,Cheprakov, A. V.,Rodkin, M. A.,Beletskaya, I. P.
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p. 211 - 217
(2007/10/02)
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- LIQUID-PHASE CATALYTIC OXIDATION OF 2,5-DIMETHYLDIPHENYLMETHANE AND ITS METHYL-, CHLORO-, AND NITRO-SUBSTITUTED DERIVATIVES
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The oxidation of 2,5-dimethyldiphenylmethane and its methyl, chloro, and nitro derivatives with oxygen in acetic acid in the presence of cobalt-manganese-bromide catalyst to benzophenone-2,5-dicarboxylic acids takes place with the intermediate formation of either 2,5-dimethylbenzophenones or products from oxidation of the methyl groups.The ratio of the oxidation paths depends on the nature of the substituent, and the contribution from the path involving initial oxidation of the methylene fragment changes with the substituents in the order 4'-CH3>H>4'-Cl>2'-Cl>4'-NO2.
- Pozdnyakovich, Yu. V.,Borodovitsyn, V. V.,Borodovitsyna, T. I.,Sysa, V. M.,Shein, S. M.
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p. 349 - 353
(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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