- Direct Hydrodecarboxylation of Aliphatic Carboxylic Acids: Metal- and Light-Free
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A mild and inexpensive method for direct hydrodecarboxylation of aliphatic carboxylic acids has been developed. The reaction does not require metals, light, or catalysts, rendering the protocol operationally simple, easy to scale, and more sustainable. Crucially, no additional H atom source is required in most cases, while a broad substrate scope and functional group tolerance are observed.
- Burns, David J.,Lee, Ai-Lan,McLean, Euan B.,Mooney, David T.
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supporting information
p. 686 - 691
(2022/01/28)
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- Mustard Carbonate Analogues as Sustainable Reagents for the Aminoalkylation of Phenols
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N,N-dialkyl ethylamine moiety can be found in numerous scaffolds of macromolecules, catalysts, and especially pharmaceuticals. Common synthetic procedures for its incorporation in a substrate relies on the use of a nitrogen mustard gas or on multistep syntheses featuring chlorine hazardous/toxic chemistry. Reported herein is a one-pot synthetic approach for the easy introduction of aminoalkyl chain into different phenolic substrates through dialkyl carbonate (β-aminocarbonate) chemistry. This new direct alcohol substitution avoids the use of chlorine chemistry, and it is efficient on numerous pharmacophore scaffolds with good to quantitative yield. The cytotoxicity via MTT of the β-aminocarbonate, key intermediate of this synthetic approach, was also evaluated and compared with its alcohol precursor.
- Annatelli, Mattia,Trapasso, Giacomo,Salaris, Claudio,Salata, Cristiano,Castellano, Sabrina,Aricò, Fabio
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supporting information
p. 3459 - 3464
(2021/05/24)
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- Oxalic Diamides and tert-Butoxide: Two Types of Ligands Enabling Practical Access to Alkyl Aryl Ethers via Cu-Catalyzed Coupling Reaction
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A robust and practical protocol for preparing alkyl aryl ethers has been developed, which relies on using two types of ligands to promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction scope is very general for a variety of coupling partners, particularly for challenging secondary alcohols and (hetero)aryl chlorides. In case of coupling with aryl chlorides and bromides, two oxalic diamides serve as the powerful ligands. The tert-butoxide is first demonstrated as a ligand for Cu-catalyzed coupling reaction, leading to alkoxylation of aryl iodides complete at room temperature. Additionally, a number of carbohydrate derivatives are applicable for this coupling reaction, affording the corresponding carbohydrate-aryl ethers in 29-98% yields.
- Chen, Zhixiang,Jiang, Yongwen,Zhang, Li,Guo, Yinlong,Ma, Dawei
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supporting information
p. 3541 - 3549
(2019/02/26)
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- Synthesis, structure, and synthetic potential of arenediazonium trifluoromethanesulfonates as stable and safe diazonium salts
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Aromatic diazonium salts are valuable building blocks for organic synthesis; however, in most cases, they are unstable, unsafe, poorly soluble, and/or expensive. In this paper, we have shown that a variety of stable and safe arenediazonium triflates ArN2+ TfO– can be obtained easily and in high yields by diazotization of anilines with tert-butyl nitrite in the presence of trifluoromethanesulfonic acid. Arenediazonium triflates are relatively shelf-stable in the dry state. They dissolve well in water, as well as polar and even nonpolar organic solvents. Less than 800 J/g of energy is released during the thermal decomposition of these salts, which indicates their explosion safety. Arenediazonium triflates have a high reactivity in the known reactions of diazonium chemistry, and undergo an unusual metal-free chlorodediazonization reaction with chloroform and CCl4.
- Filimonov, Victor D.,Krasnokutskaya, Elena A.,Kassanova, Assia Zh.,Fedorova, Valentina A.,Stankevich, Ksenia S.,Naumov, Nikolay G.,Bondarev, Alexander A.,Kataeva, Veronika A.
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p. 665 - 674
(2018/09/14)
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- Highly selective conversion of guaiacol to: Tert -butylphenols in supercritical ethanol over a H2WO4 catalyst
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The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Br?nsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
- Mai, Fuhang,Cui, Kai,Wen, Zhe,Wu, Kai,Yan, Fei,Chen, Mengmeng,Chen, Hong,Li, Yongdan
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p. 2764 - 2771
(2019/02/01)
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- Copper and l-sodium ascorbate catalyzed hydroxylation and aryloxylation of aryl halides
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CuSO4·5H2O and NaAsc catalyzed hydroxylation and C-O/C-S cross-coupling reactions of aryl halides with phenols or 4-methylbenzenethiol were described. A wide range of substrates and test cases highlight the synthetic utility of the approach. A series of phenols, diaryl ethers, alkylaryl ethers, and diaryl thioethers were synthesized in high yield.
- Song, Guang-Lin,Zhang, Zhang,Da, Yu-Xia,Wang, Xi-Cun
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supporting information
p. 8823 - 8829
(2015/10/20)
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- Practical Ligand-Free Copper-Catalysed Short-Chain Alkoxylation of Unactivated Aryl Bromides
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An efficient and practical short-chain alkoxylation of unactivated aryl bromides has been developed with special attention focussed on the applicability of the reaction. Sodium alkoxide is used as the nucleophile, and the corresponding alcohol as the solvent. The reaction requires neither precious metals nor organic ligands. It uses a catalytic system consisting of copper(I) bromide as a catalyst, the corresponding alkyl formate as a noncontaminating cocatalyst, and lithium chloride as an additive. A wide range of substrates and test cases highlight the synthetic utility of the approach. Considering the commercial accessibility and affordability of the feedstocks, this protocol shows promise as a new alternative for the sustainable preparation of aryl alkyl ethers.
- Guo, Ying,Fan, Xue-Min,Nie, Min,Liu, Hong-Wei,Liao, Dao-Hua,Pan, Xian-Dao,Ji, Ya-Fei
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p. 4744 - 4755
(2015/08/03)
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- Alkoxylation reactions of aryl halides catalyzed by magnetic copper ferrite
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Copper ferrite (CuFe2O4), which is easy-made, air-stable, low cost, easy separable, and regenerable, was applied as catalyst in an efficient method for C-O coupling reactions between various kinds of unactivated alkyl alcohols and aryl halides. This method only adopts 2.5% mol CuFe2O4 catalyst and selectively proceeds to C-O bond formation even sensitive substituents exist in the system.
- Yang, Shuliang,Xie, Wenbing,Zhou, Hua,Wu, Cunqi,Yang, Yanqin,Niu, Jiajia,Yang, Wei,Xu, Jingwei
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supporting information
p. 3415 - 3418
(2013/04/23)
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- 2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide as a novel ligand for the copper-catalyzed coupling reaction of phenols and aryl halides
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2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide was identified as an efficient novel ligand for the copper-catalyzed coupling of aryl halides with various phenols under mild conditions. The catalytic system shows great functional-group tolerance and excellent reactive selectivity.
- Qiu, Yatao,Jia, Weijun,Yao, Zhiyi,Wu, Fanhong,Jiang, Sheng
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p. 1502 - 1510
(2013/05/08)
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- Microwave-assisted methylation of phenols with DMF-DMA
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We evaluated the potential of N,N-dimethylformamide dimethylacetal (DMF-DMA) as a methylating agent for a library of para-substituted phenols under microwave irradiation. The rate of reaction was dictated by the electronic nature of the para-substituent. With an electron-withdrawing group the reaction was completed within 30 min. For electron-donating groups, the reaction times were 60 min. Esterification and enamino-ketone formation was also observed with carboxylic acid and ketone functional groups, respectively.
- Belov, Pavel,Campanella, Veronica L.,Smith, Alison W.,Priefer, Ronny
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experimental part
p. 2776 - 2779
(2011/06/19)
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- Temperature dependence of regioselectivity in nucleophilic photosubstitution of 4-nitroanisole. The activation energy criterion for regioselectivity
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Photosubstitution of the nitro group vs the methoxy group of triplet 4-nitroanisole by hydroxide ion in water leads to product yields of about 80% 4-methoxyphenol and 20% 4-nitrophenol. The ratio depends slightly on temperature from 3 to 73 °C. The slight temperature variation in the yield ratio is reproduced almost perfectly with a simple Arrhenius model for a mechanism involving bonding of hydroxide ion with the triplet state of 4-nitroanisole. The competing transition states have activation energies of 2.2 and 2.6 kcal/mol, respectively. Correct prediction of regioselectivity can be done for this case by quantum chemical calculation of the competing triplet transition-state energies, or those of the corresponding triplet σ-complexes. Other models for aromatic photosubstitution regioselectivity in mechanisms of the S N2Ar* type, such as those based on calculated electron densities, HOMO/LUMO coefficients, or energy gap sizes, are discussed and shown to be inferior to the relative activation energies model. The photoreaction in alcohol solvents, claimed by others to generate the same products as in water and to have an exceedingly large variation of the product ratio with temperature, may reflect chemical changes other than those reported.
- Wubbels, Gene G.,Danial, Hanan,Policarpio, Danielle
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experimental part
p. 7726 - 7733
(2011/03/17)
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- An efficient synthesis of phenol via CuI/8-hydroxyquinoline-catalyzed hydroxylation of aryl halides and potassium hydroxide
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The CuI/8-hydroxyquinoline-catalyzed direct hydroxylation of aryl iodides with KOH takes place at 100 C in a mixed solvent system (t-BuOH-DMSO-H 2O), providing the corresponding phenols in great diversity. Aryl bromides are found to be rather less reactive under these reaction conditions. Georg Thieme Verlag Stuttgart - New York.
- Maurer, Stefan,Liu, Wei,Zhang, Xiaojing,Jiang, Yongwen,Ma, Dawei
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scheme or table
p. 976 - 978
(2010/07/10)
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- General, mild, and intermolecular Ullmann-type synthesis of diaryl and alkyl aryl ethers catalyzed by diol-copper(I) complex
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(Chemical Equation Presented) A wide range of diaryl ethers and alkyl aryl ethers are synthesized through intermolecular C(aryl)-O bond formation from the corresponding aryl iodides/aryl bromides and phenols/alcohols through Ullmann-type coupling reaction in the presence of a catalytic amount of easily available (±)-diol L3-CuI complex under very mild reaction conditions. Less reactive aryl bromides can also be used for O-arylation of phenols under the same reaction conditions without increasing the reaction temperature, catalyst loading, and time. The catalytic system not only is capable of coupling hindered substrate but also tolerates a broad range of a series of functional groups.
- Naidu, Ajay B.,Jaseer,Sekar, Govindasamy
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supporting information; experimental part
p. 3675 - 3679
(2009/09/26)
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- An efficient intermolecular BINAM-copper(I) catalyzed Ullmann-type coupling of aryl iodides/bromides with aliphatic alcohols
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A wide range of alkyl aryl ethers are synthesized from the corresponding aryl iodides and aliphatic alcohols through Ullmann-type intermolecular coupling reactions in the presence of a catalytic amount of easily available BINAM-CuI complex. Less reactive aryl bromides have also been shown to react with aliphatic alcohols under identical reaction conditions to give good yields of the alkyl aryl ethers without increasing the reaction temperature and time.
- Naidu, Ajay B.,Sekar
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p. 3147 - 3151
(2008/09/20)
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- N,N-dimethylglycine-promoted ullmann-type coupling reactions of aryl iodides with aliphatic alcohols
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The Ullmann-type coupling reactions of aryl iodides and aliphatic alcohols occur at 110°C with N,N-dimethylglycine as the ligand, giving aryl alkyl ethers in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Zhang, Hui,Ma, Dawei,Cao, Weiguo
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p. 243 - 246
(2007/10/03)
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- The synthesis and conformation of oxygenated trianglimine macrocycles
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The synthesis of series of D2h and C2v symmetric oxygenated aromatic dicarboxaldehydes, using dilithiation methodology, is described along with their reactivity in the [3 + 3] cyclocondensation reaction with (1R,2R)-diaminocyclohexane to give oxygenated trianglimine macrocycles. Macrocycles derived from C2v symmetric dialdehydes give macrocycles with a stereogenic aromatic plane with complete diastereocontrol, as a mixture of retainers.
- Kuhnert, Nikolai,Lopez-Periago, Ana,Rossignolo, Giulia M.
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p. 524 - 537
(2007/10/03)
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- PHOTOSUBSTITUTION OF METHOXYPHENYL PHOSPHATES
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Photosubstitution of diethyl methoxyphenyl phosphate with some nucleophiles (Cl, Br, CN) in methanol gave the corresponding 4-chloro-, 4-bromo-, and 4-cyanomethoxybenzenes through a singlet excited state.In acidic media, the reaction was accelerated.Upon further irradiation, halo-substituted methoxybenene underwent dehalogenation to give methoxybenzene.Methoxybenzene also formed directly through the homolytic PO-Ar bond cleavage.The order of reactivities of the isomers of the phosphate was 4->2->3-methoxyphenyl derivatives. Key words: Photosubstitution; methoxyphenyl phosphate; chloromethoxybenzene; fluorescence.
- Nakamura, Mitsunobu,Osako, Yasuhiro,Okamoto,Yoshiki,Takamuku, Setsuo
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p. 141 - 148
(2007/10/02)
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- Process for substitution of aromatic organic compounds
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The invention relates to a process for substituting for a halogen atom attached to the nuclear carbon atom of an aromatic ring, a substituent of the formula -O-R wherein R represents alkyl, alkenyl, alkynyl or benzyl, which process comprises reacting the halogen-substituted aromatic compound with an alcoholate of the formula Mn+ [O--R]n? wherein M is an alkali metal atom or alkaline earth metal atom, n is the valency of M, and R is as defined above, in the presence of an active catalyst mixture comprising (i) a formic acid ester of an organic alcohol having the formula R2 --O--CO--H wherein R2 is as defined for R above; and (ii) a cuprous salt; in a liquid medium which is a solvent for the catalyst mixture and in which the halogen-substituted aromatic compound is at least partially soluble, under substantially anhydrous conditions and a non-oxidizing atmosphere. The invention further relates to a catalyst used in the above process.
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- Photodehalogenation of the Monochloro- and Monofluoroanisoles
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Evidence is presented for a plurality of mechanisms in the photoreduction and photonucleophilic substitution of the monochloroanisoles in alcohol solvents. 4-Chloroanisole appears to react partly via a radical anion and partly by radicals, while the reactions of 3-chloroanisole are more consistent with aryl cations and aryl radicals.The intermediates in the reaction of 2-chloroanisole, which gives no photosubstitution, are as yet not identified but are probably not radical anions.In the case of 4-chloroanisole, substitution and reduction may proceed from different states.Preliminary results on the fluoroanisoles show the 2-F isomer giving both reduction and substitution and the 3- and 4-F isomers only substitution.
- Siegman, John R.,Houser, John J.
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p. 2773 - 2779
(2007/10/02)
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- Aryl Radical Departure Aptitudes in Reactions of Diaryliodonium Fluoroborates with Sodium Ethoxide
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Several unsymmetrical diaryliodonium fluoroborates have been prepared and subjected to reaction with sodium ethoxide in ethanol solution at 71 deg C.From quantitative determinations of products, it has been possible to calculate apparent departure aptitudes of several common aryl radical cations of type 6.These results are compared with similar data obtained from thermolysis reactions of hydroxytetraarylstiboranes.
- Lubinkowski, Jacek J.,Arrieche, Cecilia Gimenez,McEwen, William E.
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p. 2076 - 2079
(2007/10/02)
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