- The effect of topologically controlled coulombic interactions on the regioselectivity of the reductive cleavage of alkyl phenyl ethers
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The importance of electrostatic effects in the chemical evolution of charged intermediates of the radical anion type is demonstrated. Thus, the regioselectivity of the electron transfer-induced reductive cleavage of alkyl 2,6-diphenylphenyl ethers and alkyl 2,6-dimethoxyphenyl ethers is completely reversed when a positive charge is placed in a controlled manner near the alkyl ether bond.
- Azzena, Ugo,Casado, Francisco,Fois, Pierfrancesco,Gallardo, Iluminada,Pisano, Luisa,Marquet, Jordi,Melloni, Giovanni
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- Probing Through-Space Polar-π Interactions in 2,6-Diarylphenols
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Although it is well established that the acidity of phenol can be fine-tuned with substituents on its aromatic ring via through-bond effects, the role of through-space effects on the acidity of phenols is presently poorly understood. Here, we present integrated experimental and computational studies on substituted 2,6-diarylphenols that demonstrate the essential contribution from through-space OH -π interactions and O--π interactions in the observed trends in proton affinities and acidities of 2,6-diarylphenols.
- Bosmans, Vera,Poater, Jordi,Hammink, Roel,Tinnemans, Paul,Bickelhaupt, F. Matthias,Mecinovi?, Jasmin
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- Through-Space Polar-π Interactions in 2,6-Diarylthiophenols
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Molecular recognition between polar groups and aromatic molecules is fundamentally important to rational drug design. Although it has been well established that many polar functionalities interact with electron-rich aromatic residues through energetically favorable polar-π interactions, there is a limited understanding of the association between thiols and aromatic systems. Herein we report physical-organic chemistry studies on 2,6-diarylthiophenols that possess the central thiophenol ring and two flanking aromatic rings with tunable electronic properties caused by substituents at distant para position. Hammett analysis revealed that pKa values and proton affinities correlate well with Hammett sigma values of substituents. Additional energy decomposition analysis supported the conclusion that both through-space SH-π interactions and S?-π interactions contribute to intramolecular stabilization of 2,6-diarylthiophenols.
- Jian, Jie,Poater, Jordi,Hammink, Roel,Tinnemans, Paul,McKenzie, Christine J.,Bickelhaupt, F. Matthias,Mecinovi?, Jasmin
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- Palladium-Catalyzed Reductive [5+1] Cycloaddition of 3-Acetoxy-1,4-enynes with CO: Access to Phenols Enabled by Hydrosilanes
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A new palladium-catalyzed reductive [5+1] cycloaddition of 3-acetoxy-1,4-enynes with CO, enabled by hydrosilanes, has been developed for delivering valuable functionalized phenols. This methodology employs hydrosilanes as the external reagent to facilitate the [5+1] carbonylative benzannulation. The reaction is a conceptually and mechanistically novel carbonylative cycloaddition route for the construction of substituted phenols, through the formation of four new chemical bonds, with excellent functional-group tolerance.
- Li, Jin-Heng,Luo, Shenglian,Song, Ren-Jie,Wu, Li-Jun
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supporting information
p. 13308 - 13312
(2018/09/21)
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- Preparation method of multi-substituted phenol
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The invention provides a preparation method of multi-substituted phenol. According to the preparation method, raw materials, namely alkyl ketone and alkene, are subjected to condensation-aromatizationunder action of a catalyst to obtain multi-substituted phenol. Compared with the prior art, the preparation method has the advantages that the raw materials are easy to obtain, the yield is high, cost is low since use of expensive metallic catalysts is avoided, and the preparation method is suitable for industrial production and the like.
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Paragraph 0039; 0040
(2018/07/30)
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- Synergetic catalytic effect of rGO, Pd, Fe3O4 and PPy as a magnetically separable and recyclable nanocomposite for coupling reactions in green media
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In this paper, rGO/Pd–Fe3O4@PPy as an efficient stable nanocomposite was synthesized. To understand the synergetic effects of rGO, Pd, Fe3O4 and PolyPyrrole, the performance of rGO/Pd–Fe3O4@PPy as a heterogeneous recyclable nanocatalyst in the green synthesis of C-C and C-O coupling products, as well as different conditions are studied. Synthesized rGO/Pd–Fe3O4@PPy was characterized by FT-IR, XRD, FE-SEM, EDS, TGA and AFM analysis. Best results are obtained under sonication in H2O for C-C coupling and by ball-milling for C-O coupling. The benefits of this method include: green solvents and conditions, absence of external base, low reaction times with high yield and easy work-up method.
- Emami, Atefeh,Ghafuri, Hossein
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- P(NMe2)3-promoted ortho-selective arylation of phenols with diaryliodonium triflates via rhodium catalysis
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Rh-catalyzed ortho-selective arylation of free phenol with diaryliodonium triflates to widely existed phenol-containing biaryls have been developed. The use of P(NMe2)3, tBuOLi and CH3CN proved to be critical for the ortho-selectivity of this reaction.
- Liu, Qi-Sheng,Wang, De-Yin,Yang, Jin-Fei,Ma, Zhong-Yi,Ye, Mengchun
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supporting information
p. 3591 - 3595
(2017/06/13)
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- Preparation method of 2,6-diphenylphenol
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The invention relates to a preparation method of 2,6-diphenylphenol. The preparation method comprises the following step: carrying out Suzuki coupling reaction on 2,6-dichlorophenol and phenylboronic acid used as raw materials by using palladium acetate and a phosphine ligand as catalysts to obtain the compound 2,6-diphenylphenol. Compared with the prior art, the method has the advantages of simple preparation technique, common and accessible catalysts, high product purity and high, simple and safe operational process and low raw material cost, and is beneficial to industrial production.
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Paragraph 0027; 0028; 0029-0055; 0056; 0057; 0058; 0059
(2017/08/28)
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- A New Route to Phenols: Palladium-Catalyzed Cyclization and Oxidation of γ,δ-Unsaturated Ketones
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We report a new strategy for the synthesis of phenols from acyclic unsaturated ketones in one pot. The reaction proceeds by palladium-catalyzed carbopalladation of an alkene with the enol form of the tethered ketone, generating a substituted cyclohexanone. Upon introduction of a terminal oxidant a palladium-catalyzed oxidation ensues to give the desired phenol. This approach allows the programming of phenol substituents on the acyclic substrate and therefore circumvents the limitations inherent in traditional syntheses of phenols.
- Samadi, Sadaf,Orellana, Arturo
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p. 2472 - 2475
(2016/08/25)
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- Highly practical iron-catalyzed C-O cleavage reactions
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Facile iron-catalyzed cleavage of various allyl, cinnamyl and benzyl C-O linkages has been effected in the presence of ethylmagnesium chloride. The protocol is operationally simple (xylene-THF, r.t., 1 h), requires low catalyst loading (1 mol% FeCl2) and tolerates halides, esters, amines, ethers and olefins. The allyl moiety is converted to volatile hydrocarbons which renders laborious product separation unnecessary.
- Gaertner, Dominik,Konnerth, Hannelore,Von Wangelin, Axel Jacobi
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p. 2541 - 2545
(2013/09/24)
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- Nucleophilic aromatic substitution of bis(pentafluorophenyl)mercury with various bulky nucleophiles and the structures of [Hg(C6F 4X-4)2] (X≤cyclo-C5H10N, OCH(CH3)2, OC(CH3)3)
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Reactions of bis(pentafluorophenyl)mercury with piperidine, sodium iso-propoxide or sodium tert-butoxide have yielded the corresponding 4-substituted tetrafluorophenylmercurials, [Hg(C6F4X-4)2] (X≤cyclo-C5H10N (1), OCH(CH3)2 (2), OC(CH3)3 (3)), in reasonable yields but the bulkier nucleophiles, cis-2,6-dimethylpiperidine and 2,6-di-iso-propylphenolate (from sodium 2,6-di-iso-propylphenolate) decomposed the mercurial into pentafluorobenzene. Treatment of bis(pentafluorophenyl)mercury with another bulky nucleophile, 2,6-diphenylphenolate (from sodium 2,6-diphenylphenolate), in methanol, resulted in the unexpected formation of [Hg(C6F4(OMe)-4)2] (4). The structures of all the mercurials have linear C-Hg-C stereochemistry with two coplanar aryl rings. Amongst a complex series of supramolecular interactions, HgO bonding is observed for the alkoxy substituted mercurials but there are no HgN interactions in the structure of bis(2,3,5,6-tetrafluoro-4-piperidinophenyl) mercury.
- Deacon, Glen B.,Junk, Peter C.,Luu, Jenny
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p. 1253 - 1259
(2013/10/22)
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- Divergent reaction pathways for phenol arylation by arynes: Synthesis of helicenes and 2-arylphenols
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Two reactions of phenols with arynes have been developed. If LiTMP base is employed, arynes generated from aryl chlorides react with phenols to form helicenes. o-Arylation of phenols can be achieved by employing tBuONa base in the presence of AgOAc. Direc
- Truong, Thanh,Daugulis, Olafs
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p. 531 - 535
(2013/05/08)
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- P-directed borylation of phenols
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Internal borylation occurs upon activation of aryl di-isopropylphosphinite boranes with HNTf2 to give heterocyclic intermediates that can be reductively quenched to afford 6 or treated with KHF2 to give the phenolic potassium aryl trifluoroborate salts 10. The latter salts are useful for Pd-catalyzed coupling with aryl iodides under Molander conditions, provided that precautions are taken to remove the KNTf2 byproduct from the preceding KHF2 step.
- Cazorla, Clément,De Vries, Timothy S.,Vedejs, Edwin
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p. 984 - 987
(2013/04/10)
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- An extremely active and general catalyst for Suzuki coupling reaction of unreactive aryl chlorides
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β-Diketiminatophosphane Pd complex 2a acted as a powerful catalyst which allows easy access to the Suzuki coupling reaction of less reactive aryl chlorides under mild conditions. A wide range of sterically hindered and deactivated aryl chlorides could be efficiently coupled at a low catalyst loading of 0.1 mol %. Furthermore, this catalytic system also proved to be highly effective in one-pot multiple couplings.
- Lee, Dong-Hwan,Jin, Myung-Jong
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supporting information; experimental part
p. 252 - 255
(2011/03/22)
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- General and highly active catalyst for mono and double Hiyama coupling reactions of unreactive aryl chlorides in water
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A new β-diketiminatophosphane Pd catalyst was found to be highly effective in the mono and double Hiyama coupling reactions of unactivated aryl chlorides in water.
- Lee, Dong-Hwan,Jung, Ji-Young,Jin, Myung-Jong
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supporting information; experimental part
p. 9046 - 9048
(2011/02/17)
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- METHOD FOR THE PRODUCTION OF 4,4'-[1-TRIFLUOROMETHYL)ALKYLIDENE]-BIS-(2,6-DIPHENYLPHENOLS)
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The present invention relates to a process for preparing 4,4′-[1-(trifluoromethyl)alkylidene]bis(2,6-diphenylphenols), in particular for preparing 4,4′-[1-(trifluoromethyl)ethylidene]bis(2,6-diphenylphenol), which comprises the self-condensation of cyclohexanone in the presence of a basic catalyst to form tricyclic condensation products, dehydrogenation of the resulting tricyclic condensation products in the presence of a supported transition metal catalyst in the condensed phase to form 2,6-diphenylphenol and reaction of the 2,6-diphenylphenol with a trifluoromethyl ketone. The invention further provides an improved process for preparing 2,6-diphenylphenol by aldol self-condensation of cyclohexanone.
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Page/Page column 10
(2010/12/29)
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- About selective methods of synthesis of 6-tert-butyl-2-methylphenol and 6-tert-butyl-2,4-dimethylphenol
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Vapor phase catalytic methylation with methanol of 2-tert-butylphenol at the temperature 280-300°C proceeds selectively with formation of 6-tert-butyl-2-methylphenol. Elevating reaction temperature above 300°C leads to formation of 2,6-dimethylphenol. Reaction of 2-tert-butylphenol with methanol in alkaline medium in the presence of zinc oxide is shown to lead initially to formation of a mixture of calixarenes and methylenebisphenols that at elevated temperature exert splitting leading in future to 6-tert-butyl-2,4-dimethylphenol. Obtaining it in this reaction from 2,2′-methylenebis-(6-tert-butyl-4-methylphenol) proceeds selectively. Pathways of the reductive methylation of methylenebisphenols with methanol in alkaline medium is considered.
- Krysin,Khlebnikova,Khlebnikov,Pokrovskii,Vasil'ev
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experimental part
p. 1156 - 1162
(2011/05/04)
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- Rhodium-HMPT-catalyzed direct ortho arylation of phenols with aryl bromides
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Direct ortho arylation of phenols with aryl bromides catalyzed by a rhodium complex and hexamethylphosphorous triamide (HMPT) have been developed. A plausible reaction mechanism involving in situ generation of arylphosphites from phenols and HMPT, phosphorus-directed ortho metalation, and transesterification of the arylated arylphosphites with the substrate phenols is proposed.
- Oi, Shuichi,Watanabe, Shun-Ichiro,Fukita, Susumu,Inoue, Yoshio
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p. 8665 - 8668
(2007/10/03)
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- Electrostatic and electrophilic catalysis in the reductive cleavage of alkyl aryl ethers. The influence of ion pairing on the regioselectivity
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Electrophilic and electrostatic catalysis have been identified as distinct contributions that affect the reactivity of radical anions in the reductive cleavage of alkyl aryl ethers. Two modes of mesolytic scission of these radical anions are possible: homolytic (dealkylation, a thermodynamically favored but kinetically forbidden process) and heterolytic (dealkoxylation). From our studies (alkali metal reductions, electrochemical studies, use of substrates with a preformed positive charge in certain positions of their structure) it can be concluded that the heterolytic scission is very much dependent on the electrophilic assistance by the counterion and it is only observed in contact ionic pairs with unsaturated cations (electrophilic catalysis). On the other hand, the homolytic scission is observed in solvent-separated ionic pairs, and it is especially efficient when the pair has a controlled topology with a tetralkylammonium cation (saturated cation) near the oxygen atom. The effect of the cation has, in this case, electrostatic origin (electrostatic catalysis), probably lowering the barrier of the intramolecular π*-σ* electron transfer process and thus reducing the kinetic control of the reaction in such a way that the thermodynamically more favorable process is produced.
- Casado, Francisco,Pisano, Luisa,Farriol, Maria,Gallardo, Iluminada,Marquet, Jordi,Melloni, Giovanni
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p. 322 - 331
(2007/10/03)
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- Stoichiometric reaction of titanacyclopentadiene compounds with allylic ethers: Regiochemistry of methylenecyclohex-3-ene formation
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The titanacyclopentadiene complexes [(ArO)2Ti(C4Et4)] (1a), [(ArO)2Ti(C4Et2(CH2)4)] (1b) and [(ArO)2Ti(C4Bu2(t)H2)] (1c) (ArO = 2,6-diphenylphenoxide) react with allylphenylether to produce new organometallic products containing cyclohexadienemethyl and phenoxide ligands. Hydrolysis of these compounds leads to the formation of single regioisomers of substituted methylenecyclohex-3-ene along with two equivalents of 2,6-diphenylphenol and one equivalent of phenol. A reaction sequence involving initial (2+2+2) cycloaddition followed by cleavage of a phenyl ether bond is discussed.
- Balaich, Gary J.,Rothwell, Ian P.
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p. 4463 - 4470
(2007/10/02)
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- Intramolecular Arene Hydrogenation at Niobium Metal Centres: Stereochemical Consequences
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Selective hydrogenation of 2,6-diphenylphenoxide to 2,6-dicyclohexylphenoxide ligands takes place at niobium(v) metal centres.
- Steffey, Bryan D.,Rothwell, Ian P.
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p. 213 - 215
(2007/10/02)
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- THE CHEMISTRY OF PENTAVALENT ORGANOBISMUTH REAGENTS. PART X. STUDIES ON THE PHENYLATION AND OXIDATION OF PHENOLS
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The influence of the substituents on the phenol on the regiochemistry of the arylation reactions with Ph3BiCl2 and other bismuth reagents has been studied.O-Phenylation occurs with phenols substituted with electron-withdrawing groups.Electron-donating substituted phenols undergo ortho C-phenylation.Oxidative dimerisation has been observed with 2,6-dialkyl phenols.
- Barton, Derek H. R.,Yadav-Bhatnagar, Neerja,Finet, Jean-Pierre,Khamsi, Jamal,Motherwell, William B.,Stanforth, Stephen P.
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p. 323 - 332
(2007/10/02)
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- 2,7-Diphenyloxepin
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A synthesis of 2,7-diphenyloxepin (1d) is described.Acid-catalyzed isomerization of 1d gives 2,6-diphenylphenol (4d) in quantitative yield.X-ray crystal structure analysis indicates that oxepin 1d exists in a boat conformation in the solid state.
- McManus, Michael J.,Berchtold, Glenn A.,Boyd, Derek R.,Kennedy, Deirdre A.,Malone, John F.
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p. 2784 - 2787
(2007/10/02)
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