- Ortho derivatization of phenols through C-H nickelation: Synthesis, characterization, and reactivities of ortho-nickelated phosphinite complexes
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Reported here are the synthesis and characterization of ortho-nickelated complexes derived from phosphinite ligands and investigated as model compounds in the development of C-H functionalization strategies for arenol substrates. Reaction of i-Pr2POPh with 0.6 equiv of [(i-PrCN)NiBr2]n and 0.8 equiv of NEt3 in toluene (100 °C, 36 h) gave the yellow, monomeric cyclometalated complex trans-{κ2P,C-C6H4OP(i-Pr)2}Ni(i-Pr2POPh)Br (3a) in 93% yield. The closely related yellow-orange dimeric species [{κ2P,C-C6H4OP(i-Pr)2}Ni(μ-Br)]2 (4a) was obtained in 70% yield when i-Pr2POPh was treated with 2 equiv each of the Ni precursor and NEt3. These complexes have been characterized fully and shown to interconvert in the presence of excess ligand (4a → 3a) or excess Ni precursor (3a → 4a). Treatment of 3a or 4a with benzyl bromide at 90°C over extended periods led to benzylation of the Ni-aryl moiety in these complexes. Examination of the cyclometalation pathway for i-Pr2POPh has shown that the first species formed from its ambient-temperature reaction with [(i-PrCN)NiBr2]n is trans-(i-Pr2POPh)2NiBr2 (2a). NMR studies showed that 2a undergoes a rapid ligand exchange at room temperature, which can be slowed down at -68°C; this fluxional process shifts in the presence of NEt3, implying the partial formation of an amine adduct. Heating toluene mixtures of 2a and NEt3 at 90°C for 38 h led to the formation of 3a via C-H nickelation. That phosphinite dissociation from 2a precedes the C-H nickelation step is implied by the observation that the formation of 3a is hindered in the presence of excess i-Pr2POPh. The impact of phenol ring substituents on the C-H nickelation rate was probed by preparing substituted derivatives of 2a, trans-(4-R-C6H4OP(i-Pr2)}2NiBr2 (R = OMe (2b), Me (2c), COOMe (2d)), and measuring their relative rates of C-H nickelation. These studies showed that the formation of cyclonickelated products is favored in the order COOMe 6H4OP(i-Pr2) allowed us to establish that metalation is favored at the para position with respect to F (85:15).
- Vabre, Boris,Deschamps, Flix,Zargarian, Davit
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- Metal triflate formation of C12-C22phenolic compounds by the simultaneous C-O breaking and C-C coupling of benzyl phenyl ether
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Catalytic pathways to produce high carbon number compounds from benzyl phenyl ether require multiple steps to break the aryl etheric carbon-oxygen bonds; these steps are followed by energy-intensive processes to remove oxygen atoms and/or carbon-carbon coupling. Here, we show an upgrading strategy to transform benzyl phenyl ether into large phenolic (C12-C22) compounds by a one-step C-O breaking and C-C coupling catalyzed by metal triflates under a mild condition (100 °C and 1 bar). Hafnium triflate was the most selective for the desired products. In addition, we measured the effect of solvent polarity on the catalytic performance. Solvents with a polarity index of less than 3.4 promoted the catalytic activity and selectivity to C12-C22 phenolic products. These C12-C22 phenolic compounds have potential applications for phenol-formaldehyde polymers, diesel/jet fuels, and liquid organic hydrogen carriers. This journal is
- Hossain, Md. Anwar,Maihom, Thana,Mills, Kyle,Molley, Ashten,Rahaman, Mohammad Shahinur,Sathitsuksanoh, Noppadon,Tulaphol, Sarttrawut,Yelle, Daniel
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supporting information
p. 17390 - 17396
(2021/12/10)
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- Towards ortho-selective electrophilic substitution/addition to phenolates in anhydrous solvents
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Alkyl-substituted Li-phenolates with BnBr in water solution lead to a mixture of o- and p-Bn-substituted phenols together with a substantial amount of phenol Bn ether. In CPME, and especially in toluene with 1–2 equivalents of ether or alcohol additives, ortho-selective alkylation is achieved. In the case of o,o,p-tri- and o,o-di-substituted phenols dearomatization occurs affording o-Bn-substituted alkyl cyclohexadienones with yields up to 92% with an o/p ratio up to 90/1.
- Lopu?anskaja, Eleana,Kooli, Anni,Paju, Anne,J?rving, Ivar,Lopp, Margus
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- Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
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Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.
- Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
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p. 6107 - 6116
(2021/02/01)
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- Conversion of Aryl Aldehydes to Benzyl Iodides and Diarylmethanes by H3PO3/I2
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For the first time, H3PO3 was used as both the reducing reagent and the promotor in the reductive benzylation reactions with aryl aldehydes. By using a H3PO3/I2 combination, various aromatic aldehydes underwent iodination reactions and Friedel-Crafts type reactions with arenes via benzyl iodide intermediates, readily producing benzyl iodides and diarylmethanes in good yields. Intramolecular cyclization reactions also took place, giving the corresponding cyclic compounds. This new strategy features easy-handling, low-cost, and metal-free conditions.
- Lv, Fang,Xiao, Jing,Xiang, Junchun,Guo, Fengzhe,Tang, Zi-Long,Han, Li-Biao
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p. 3081 - 3088
(2021/02/01)
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- Preparation method of diarylmethane and derivatives thereof
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The invention discloses a preparation method of a diarylmethane compound and a derivative thereof. In a protective atmosphere, heating reaction is carried out on aryl aldehyde and an aromatic hydrocarbon compound in the presence of phosphorous acid and elemental iodine to obtain diarylmethane and the derivative thereof. According to the method, cheap and green solid phosphorous acid is selected as a reducing reagent and an accelerant for reaction, the diarylmethane and the derivative thereof are efficiently prepared by a one-pot one-step method starting from a simple and easily available aryl aldehyde compound in the presence of elemental iodine, and the method has the advantages of simplicity in operation, cheap and easily available reagents, environmental friendliness and the like; use of expensive reducing reagents, metal reagents and transition metal catalysts is avoided, and industrial production is facilitated.
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Paragraph 0114-0117
(2021/04/21)
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- Insight into the chemoselective aromatic: Vs. side-chain hydroxylation of alkylaromatics with H2O2catalyzed by a non-heme imine-based iron complex
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The oxidation of a series of alkylaromatic compounds with H2O2 catalyzed by an imine-based non-heme iron complex prepared in situ by reaction of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2?:?2?:?1 ratio leads to a marked chemoselectivity for aromatic ring hydroxylation over side-chain oxidation. This selectivity is herein investigated in detail. Side-chain/ring oxygenated product ratio was found to increase upon decreasing the bond dissociation energy (BDE) of the benzylic C-H bond in line with expectation. Evidence for competitive reactions leading either to aromatic hydroxylation via electrophilic aromatic substitution or side-chain oxidation via benzylic hydrogen atom abstraction, promoted by a metal-based oxidant, has been provided by kinetic isotope effect analysis. This journal is
- Ticconi, Barbara,Capocasa, Giorgio,Cerrato, Andrea,Di Stefano, Stefano,Lapi, Andrea,Marincioni, Beatrice,Olivo, Giorgio,Lanzalunga, Osvaldo
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p. 171 - 178
(2021/01/28)
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- Cleavage of aryl-ether bonds in lignin model compounds using a Co-Zn-beta catalyst
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Efficient cleavage of aryl-ether linkages is a key strategy for generating aromatic chemicals and fuels from lignin. Currently, a popular method to depolymerize native/technical lignin employs a combination of Lewis acid and hydrogenation metal. However, a clear mechanistic understanding of the process is lacking. Thus, a more thorough understanding of the mechanism of lignin depolymerization in this system is essential. Herein, we propose a detailed mechanistic study conducted with lignin model compounds (LMC) via a synergistic Co-Zn/Off-Al H-beta catalyst that mirrors the hydrogenolysis process of lignin. The results suggest that the main reaction paths for the phenolic dimers exhibiting α-O-4 and β-O-4 ether linkages are the cleavage of aryl-ether linkages. Particularly, the conversion was readily completed using a Co-Zn/Off-Al H-beta catalyst, but 40% of α-O-4 was converted and β-O-4 did not react in the absence of a catalyst under the same conditions. In addition, it was found that the presence of hydroxyl groups on the side chain, commonly found in native lignin, greatly promotes the cleavage of aryl-ether linkages activated by Zn Lewis acid, which was attributed to the adsorption between Zn and the hydroxyl group. Followed by the cobalt catalyzed hydrogenation reaction, the phenolic dimers are degraded into monomers that maintain aromaticity. This journal is
- Chang, Hou-Min,Dou, Xiaomeng,Jameel, Hasan,Jiang, Xiao,Li, Wenzhi,Zhu, Chaofeng
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p. 43599 - 43606
(2020/12/25)
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- Benzylic C?H Functionalisation by [Et3SiH+KOtBu] leads to Radical Rearrangements in o-tolyl Aryl Ethers, Amines and Sulfides
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Reaction of Et3SiH+KOtBu with diaryl ethers, sulfides and amines that feature an ortho alkyl group leads to rearrangement products. The rearrangements arise from formation of benzyl radicals, likely formed through hydrogen atom abstraction by triethylsilyl radicals. The rearrangements involve cyclisation of the benzyl radical onto the partner arene, which, from computation, is the rate determining step. In the case of diaryl ethers, Truce-Smiles rearrangements arise from radical cyclisations to form 5-membered rings, but for diarylamines, cyclisations to form dihydroacridines are observed. (Figure presented.).
- Arokianathar, Jude N.,Kolodziejczak, Krystian,Bugden, Frances E.,Clark, Kenneth F.,Tuttle, Tell,Murphy, John A.
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p. 2260 - 2267
(2020/05/06)
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- Preparation method of alkyl aromatic compound based on alkenyl ether Friedel-Crafts reaction
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The invention discloses a preparation method of an alkyl aromatic compound based on an alkenyl ether Friedel-Crafts reaction, and belongs to the technical field of pharmaceutical and chemical intermediates and related chemistry. According to the method, alkenyl ether and an aromatic compound are used as raw materials, and green and efficient synthesis of the alkyl-substituted aromatic compound isrealized under the catalytic action of Lewis acid or protonic acid. The method has the advantages of high selectivity, mild reaction conditions, good functional group compatibility, the wide substraterange, environmental friendliness and the like. The alkyl-substituted aromatic compound is an important organic synthesis intermediate and has very wide application in the fields of organic synthesisand pharmacy, so that the alkyl-substituted aromatic compound has relatively high application value and social and economic benefits.
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Paragraph 0055-0057
(2020/07/24)
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- Synthesis of Highly Substituted Phenols and Benzenes with Complete Regiochemical Control
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Substituted phenols are requisite molecules for human health, agriculture, and diverse synthetic materials. We report a chemical synthesis of phenols, including penta-substituted phenols, that accommodates programmable substitution at any position. This method uses a one-step conversion of readily available hydroxypyrone and nitroalkene starting materials to give phenols with complete regiochemical control and in high chemical yield. Additionally, the phenols can be converted into highly and even fully substituted benzenes.
- Zhang, Xiaojie,Beaudry, Christopher M.
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supporting information
p. 6086 - 6090
(2020/08/12)
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- Palladium-catalyzed aerobic synthesis of: Ortho -substituted phenols from cyclohexanones and primary alcohols
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Due to the importance of phenols as structural cores and precursors of chemical products, synthesis of site-specific substituted phenols is highly desirable and a significant challenge. An aerobic palladium-catalyzed site-specific synthesis of ortho-substituted phenols from cyclohexanones and primary alcohols via an oxidation/aldol/dehydration/aromatization process has been developed. Various substituted cyclohexanones and primary alcohols are successfully transformed into ortho-substituted phenols. In addition, this catalytic reaction uses air as the terminal oxidant and generates water as the sole by-product. Furthermore, the method can also be extended to polyhydroxyl substituted substrates with high chemoselectivity between primary and secondary alcohols. This method provides a greener tool for synthesizing primary alkyl ortho-substituted phenols.
- Zeng, Huiying,Yu, Jianjin,Li, Chao-Jun
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supporting information
p. 1239 - 1242
(2020/02/04)
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- Recyclable Pd/C catalyzed one-step reduction of carbonyls to hydrocarbons under simple conditions without extra base
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The reductions of carbonyls for the synthesis of hydrocarbons were developed with hydrazine hydrate, hydrogen gas and ammonium formate respectively. The simple, mild and efficient conditions were provided by employing recyclable Pd/C as catalyst in normal solvents at 100 °C and the reactions proceeded smoothly to produce the corresponding products with good to excellent yields. And gram-scale reactions and recycling of the catalyst were also demonstrated. Furtherly, the mechanism has been proposed.
- Zhou, Xiao-Yu,Chen, Xia
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supporting information
(2019/12/06)
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- Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
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For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
- Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
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p. 22343 - 22347
(2019/07/31)
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- Mild Friedel–Crafts Reactions inside a Hexameric Resorcinarene Capsule: C?Cl Bond Activation through Hydrogen Bonding to Bridging Water Molecules
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A novel catalytic feature of a hexameric resorcinarene capsule is highlighted. The self-assembled cage was exploited to promote the Friedel–Crafts benzylation of several arenes and heteroarenes with benzyl chloride under mild conditions. Calculations showed that there are catalytically relevant hydrogen-bonding interactions between the bridging water molecules of the capsule and benzyl chloride, which is fundamental for the activation of the C?Cl bond. The capsule controls the reaction outcome. Inside the inner cavity of the capsule, N-methylpyrrole is preferentially benzylated in the unusual β-position while mesitylene reacts faster than 1,3-dimethoxybenzene despite the greater π-nucleophilicity of the latter compound.
- La Manna, Pellegrino,Talotta, Carmen,Floresta, Giuseppe,De Rosa, Margherita,Soriente, Annunziata,Rescifina, Antonio,Gaeta, Carmine,Neri, Placido
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p. 5423 - 5428
(2018/04/09)
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- Spectroscopic Investigation of Thermochemical Depolymerization of Lignin Model Compounds in the Presence of Novel Liquidlike Nanoparticle Organic Hybrid Solvents for Efficient Biomass Valorization
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This study reports the thermochemical transformation of lignin model compounds using nanoparticle organic hybrid materials (NOHMs). NOHMs have recently been developed as an emerging class of self-suspended nanoparticle solvent systems created by ionically or covalently grafting organic oligomers or polymers (canopy) onto surface-modified inorganic nanoparticles (core). Because NOHMs exhibit negligible vapor pressure with the ability to tailor physicochemical properties, they could be a promising catalytic solvent for the lignin thermochemical conversion process. The thermochemical conversion of lignin model compounds was achieved with the synthesized NOHM at an elevated temperature of 473 K, and the results were compared with the case of the ionic liquid [EMIM][ESO4]. The fractured moieties of the lignin model compounds were qualitatively identified by ATR FT-IR and 2D COSY NMR spectroscopies. The results indicated that the NOHM decomposed the C-O and/or C-C bonds of lignin model chemicals more efficiently than [EMIM][ESO4].
- Moon, Seokyoon,Lee, Yunseok,Choi, Soyoung,Hong, Sujin,Lee, Seungin,Park, Ah-Hyung A.,Park, Youngjune
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p. 1723 - 1732
(2019/01/04)
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- Degradation of the antibacterial agents triclosan and chlorophene using hydrodechlorination by Al-based alloys
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Abstract: Triclosan and chlorophene are chlorinated phenols used as antimicrobial agents. Both compounds are ordinarily detected in aquatic environments. The aim of this study is to prove the reactivity of three different metallic alloys used as common re
- Pérko, Jan,Kamenická, Barbora,Weidlich, Tomá?
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p. 1777 - 1786
(2018/08/17)
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- Effects of Sugars, Furans, and their Derivatives on Hydrodeoxygenation of Biorefinery Lignin-Rich Wastes to Hydrocarbons
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Hydrodeoxygenation of biorefinery lignin-rich wastes to jet fuel hydrocarbons offers a significant opportunity for enhancing the overall operational efficiency, carbon conversion efficiency, economic viability, and sustainability of biofuels production. However, these wastes usually mainly contain lignin with sugars, furans, and their derivatives as “impurities”. Although several factors, including reactant structure, solvents, or the decreased ratio of catalyst to reactant, could be responsible for the jet fuel hydrocarbons yield loss, we found evidence that glucose, xylose, and 5-hydroxymethylfurfural dramatically decreased conversion yields. For example, xylose and glucose lowered the final hydrocarbon yield by 78 and 63 %, respectively. The results revealed that these compounds could suppress metal catalysts and inhibit lignin depolymerization and hydrodeoxygenation (HDO) reactions thus decrease yields of jet fuel range hydrocarbons from biomass-derived lignin. The first-principles calculations and TGA results from spent catalysts validated these findings.
- Wang, Hongliang,Duan, Yuhua,Zhang, Qian,Yang, Bin
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p. 2562 - 2568
(2018/08/01)
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- Metal-Free C-O Bond Functionalization: Catalytic Intramolecular and Intermolecular Benzylation of Arenes
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A catalytic, metal-free intramolecular rearrangement of benzyl phenyl ethers using nitrosonium salt as a catalyst is described. The optimized reaction conditions enabled a catalytic and metal-free Friedel-Crafts alkylation reaction with benzylic alcohols, producing water as the stoichiometric byproduct. A comprehensive scope (>50 examples) for both approaches and application in drug synthesis were demonstrated. Mechanistic studies suggest a Lewis acid-based mechanism for the metal-free Friedel-Crafts reaction.
- Bering, Luis,Jeyakumar, Kirujan,Antonchick, Andrey P.
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p. 3911 - 3914
(2018/07/22)
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- A green synthetic benproperine phosphate in intermediates (by machine translation)
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A green synthetic benproperine phosphate in intermediates, which belongs to the technical field of pharmaceutical intermediates. The process in the phenol and benzyl alcohol benzylating reaction, the introduction of 1, 1, 3, 3 - [...] sulfonyl propylene (TTP)/hexafluoroisopropanol (HFIP) catalytic system, the steps of reaction to enhance the yield of 95% - 100%; after a series of reaction can obtain the target product benproperine phosphate, avoid the Al2 O3 First activated and reaction, the production process is greatly simplified, improving the selectivity, yield is greatly improved. In the substituted hydroxy substitution chlorine in the step into, the introduction of methyl dichloro silane, anhydrous ferric trichloride, ethylene glycol dimethyl ether replacing thionyl chloride, benzene and pyridine. No sulfur dioxide, hydrogen chloride and other corrosive contaminants. Reduces the environment pollution and difficulty of post-processing; and easy operation, processing is simple. The method greatly improves the yield, the cost is reduced, and the safety is improved, and the energy is saved, accord with the green reaction of modern chemical production requirement. (by machine translation)
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Paragraph 0016; 0017; 0018
(2018/11/22)
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- Highly selective catalytic hydroconversion of benzyloxybenzene to bicyclic cyclanes over bifunctional nickel catalysts
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An active bifunctional nickel catalyst was prepared by decomposing Ni(CO)4 to highly dispersed metallic Ni onto Hβ zeolite and first applied in hydroconverting benzyloxybenzene (BOB), which was used as a lignin-related model compound. Ni/Hβ proved to be effective for converting BOB to bicyclic cyclanes (BCCs) via Calk–O bond cleavage induced by H+ addition, benzylium addition to 2- and 4-positions in phenol, hydrogenation of benzene ring, dehydration, and H? abstraction. Compared to one-step conversion, the total BCC selectivity (TBCCS) significantly increases from catalytic hydroconversion of catalytically converted BOB by pretreatment under pressurized N2.
- Zhou, Xiao,Wei, Xian-Yong,Liu, Zhong-Qiu,Lv, Jing-Hui,Wang, Yue-Lun,Li, Zhan-Ku,Zong, Zhi-Min
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- Protecting group-free use of alcohols as carbon electrophiles in atom efficient aluminium triflate-catalysed dehydrative nucleophilic displacement reactions
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Benzylic and allylic alcohols are rendered electrophilic without chemical modification by the use of aluminium triflate as catalyst. The reaction succeeds with alcohol, thiol, carbon and nitrogen nucleophiles. When phenols are employed as nucleophiles, C-alkylation ensues. An advanced application of the method is demonstrated in the synthesis of 2H-chromenes and their N and S analogues.
- Cullen, Adam,Muller, Alfred J.,Williams, D. Bradley G.
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p. 42168 - 42171
(2017/09/11)
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- Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes
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The reactions of five dinuclear carbonyl complexes [(η 5-C5Me4R)Mo(CO)3]2 [R = allyl, n Bu, t Bu, Ph, Bz] with I2 in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η 5-C5Me4R)MoI(CO)3] [R = allyl (1), n Bu (2), t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo-I bond distances; the more sterically hindered the substituent, the longer the Mo-I bond. Friedel-Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel-Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.
- Ma, Zhi-Hong,Lv, Lin-Qian,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 225 - 233
(2016/02/20)
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- Synthesis and catalytic activity of monobridged bis(cyclopentadienyl)rhenium carbonyl complexes
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Thermal treatment of three monobridged biscyclopentadienes (C5H5)R(C5H5) [R?=?C(CH3)2 (1), C(CH2)5 (2), Si(CH3)2 (3)] with Re2(CO)10 in refluxing mesitylene gave the corresponding complexes [(η5-C5H4)2R][Re(CO)3]2 [R?=?C(CH3)2 (4), C(C5H10) (5), Si(CH3)2 (6)], which were separated by chromatography, and characterized by elemental analysis, IR, and 1H NMR spectroscopy. The molecular structures of complexes 5 and 6 were characterized by X-ray crystal diffraction analysis and show that both are monobridged bis(cyclopentadienyl)rhenium carbonyl complexes in which the molecule consists of two [(η5-C5H4)Re(CO)3] moieties linked by a single bridge, in which each of the two Re(CO)3 units is coordinated to the cyclopentadienyl ring in an η5 mode. All three of these monobridged bis(cyclopentadienyl)rhenium carbonyl complexes have good catalytic activities in Friedel–Crafts alkylation reactions.
- Li, Zhen,Ma, Zhi-Hong,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 647 - 653
(2016/07/29)
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- Decomposition of lignin model compounds by Lewis acid catalysts in water and ethanol
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The conversion of benzyl phenyl ether, diphenyl ether, diphenyl methane and biphenyl as representative model compounds for α-O4, 5-O4, α 1 (methylene bridges) and 5-5′ lignin linkages was investigated. We compared the use of metal chlorides and acetates. The reactions were studied in sub- and supercritical water and supercritical ethanol between 300 and 400 °C. At low temperature in water, Lewis acids mainly catalyzed condensation of hydrolysis products of the dimeric model compounds. At higher temperature, mono-aromatic products were formed. The yield of monomeric products was higher in ethanol than in water. The preference for ethanol is due to extensive alkylation of the mono-aromatic products, which inhibits their condensation into larger products. The highest yields of deoxygenated mono-aromatics were obtained using Lewis acid catalysts at 400 °C in supercritical ethanol. The preferred Lewis acid catalysts were Fe, Cu, Ni and Al chlorides.
- Güvenatam, Burcu,Heeres, Erik H.J.,Pidko, Evgeny A.,Hensen, Emiel J.M.
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- Low-temperature oxidation of Methylene bridge bond in coal by model compound
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In order to find out characteristics of active structures in coal at early phase of oxidation, diphenylmethane was adopted as the model compound to study the oxidation properties of bridge bond (methylene) in coal with low-temperature experimental condition (293 K-423 K), according to structure of molecular coal. Mean while, the generated oxidation products under different reaction conditions were analyzed qualitatively via FTIR spectrometer and GC-MS. The results show that the new structures which involve C-O, C=O, Ar-O and Ar-OH are constantly generated with temperature rise in the process of low-temperature oxidation of diphenylmethane, especially after the 393 K. Besides, the phenols, benzaldehyde, diphenylmethanone, phenyl benzoate, 2-benzyl phenols and 2-phenolic-diphenylmethanone were detected in oxidation products, which demonstrated this oxidation is a multi-step reaction. Meantime, the substitution between O and H is more easily occurs in -CH2-than in benzene ring. The temperature and time are major factors which affecting low-temperature oxidation of diphenylmethane. In conclusion, this study provides reference for explaining and controlling the low-temperature oxidation of coal from chemical perspective.
- Tang, Yibo,Li, Zenghua,Tien, Jerry C.,Yin, Wenxuan,Ma, Dongjuan
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p. 795 - 798
(2014/06/09)
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- Influence of calcium(II) and chloride on the oxidative reactivity of a manganese(II) complex of a cross-bridged cyclen ligand
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Available data from different laboratories have confirmed that both Ca2+ and Cl- are crucial for water oxidation in Photosystem II. However, their roles are still elusive. Using a manganese(II) complex having a cross-bridged cyclen ligand as a model, the influence of Ca2+ on the oxidative reactivity of the manganese(II) complex and its corresponding manganese(IV) analogue were investigated. It has been found that adding Ca2+ can significantly improve the oxygenation efficiency of the manganese(II) complex in sulfide oxidation and further accelerate the oxidation of sulfoxide to sulfone. Similar improvements have also been observed for Mg2+, Sr2+, and Ba2+. A new monomeric manganese(IV) complex having two cis-hydroxide ligands has also been isolated through oxidation of the corresponding manganese(II) complex with H2O2 in the presence of NH4PF6. This rare cis-dihydroxomanganese(IV) species has been well characterized by X-ray crystallography, electrochemistry, electron paramagnetic resonance, and UV-vis spectroscopy. Notably, using the manganese(IV) complex as a catalyst demonstrates higher activity than the corresponding manganese(II) complex, and adding Ca2+ further improves its catalytic efficiency. However, adding Cl- decreases its catalytic activity. In electrochemical studies of manganese(IV) complexes with no chloride ligand present, adding Ca2+ positively shifted the redox potential of the MnIV/MnIII couple but negatively shifted its MnV/MnIV couple. In the manganese(II) complex having a chloride ligand, adding Ca2+ shifted both the MnIV/MnIII and MnV/MnIV couples in the negative direction. The revealed oxidative reactivity and redox properties of the manganese species affected by Ca2+ and Cl- may provide new clues to understanding their roles in the water oxidation process of Photosystem II.
- Zhang, Zhan,Coats, Katherine L.,Chen, Zhuqi,Hubin, Timothy J.,Yin, Guochuan
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supporting information
p. 11937 - 11947
(2015/01/09)
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- Iron-catalyzed arylation of aromatic ketones and aldehydes mediated by organosilanes
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A simple and efficient iron-catalyzed method for arylation of aromatic carbonyl compounds is reported. The use of 4-% FeCl3 or Fe(acac) 3 as the catalyst, in combination with a slight excess of chlorotrimethylsilane and triethylsilane, chlorination of benzylic ketones and aldehydes with subsequent Friedel-Crafts alkylation of arenes is achieved. Although the method is limited by the general constraints associated with Friedel-Crafts alkylation reactions, robust applications for the synthesis of pharmaceutical intermediates and so on can be envisioned. A robust one-pot, iron-catalyzed chlorination Friedel-Crafts alkylation reaction of benzylic carbonyl compounds, mediated by chlorotrimethylsilane and triethylsilane, has been developed to yield substituted diaryl and triaryl building blocks. Copyright
- Savela, Risto,Majewski, Marcin,Leino, Reko
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p. 4137 - 4147
(2014/07/08)
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- Mechanisms of catalytic cleavage of benzyl phenyl ether in aqueous and apolar phases
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Catalytic pathways for the cleavage of ether bonds in benzyl phenyl ether (BPE) in liquid phase using Ni- and zeolite-based catalysts are explored. In the absence of catalysts, the C-O bond is selectively cleaved in water by hydrolysis, forming phenol and benzyl alcohol as intermediates, followed by alkylation. The hydronium ions catalyzing the reactions are provided by the dissociation of water at 523 K. Upon addition of HZSM-5, rates of hydrolysis and alkylation are markedly increased in relation to proton concentrations. In the presence of Ni/SiO2, the selective hydrogenolysis dominates for cleaving the Caliphatic-O bond. Catalyzed by the dual-functional Ni/HZSM-5, hydrogenolysis occurs as the major route rather than hydrolysis (minor route). In apolar undecane, the non-catalytic thermal pyrolysis route dominates. Hydrogenolysis of BPE appears to be the major reaction pathway in undecane in the presence of Ni/SiO2 or Ni/HZSM-5, almost completely suppressing radical reactions. Density functional theory (DFT) calculations strongly support the proposed C-O bond cleavage mechanisms on BPE in aqueous and apolar phases. These calculations show that BPE is initially protonated and subsequently hydrolyzed in the aqueous phase. DFT calculations suggest that the radical reactions in non-polar solvents lead to primary benzyl and phenoxy radicals in undecane, which leads to heavier condensation products as long as metals are absent for providing dissociated hydrogen.
- He, Jiayue,Lu, Lu,Zhao, Chen,Mei, Donghai,Lercher, Johannes A.
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- Copper-catalyzed oxidative aromatization of 2-cyclohexen-1-ones to phenols in the presence of catalytic hydrogen bromide under molecular oxygen
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Catalytic oxidative aromatization has been achieved using 2-cyclohexen-1-ones to obtain phenol derivatives in the presence of a catalytic amount of copper salt and aqueous HBr under molecular oxygen. The amount of HBr was successfully reduced to a catalytic quantity, and the other additive such as a ligand and an oxidant as well as inert conditions were unnecessary. Various mono-, di-, and trisubstituted phenols with substituents at the desired positions could be synthesized under cheap and simple conditions. An oxidative aromatization/bromination sequence was also demonstrated to obtain bromophenols with excess HBr. The Royal Society of Chemistry 2013.
- Kikushima, Kotaro,Nishina, Yuta
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p. 20150 - 20156
(2013/11/06)
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- Nickel-catalyzed cross couplings of benzylic ammonium salts and boronic acids: Stereospecific formation of diarylethanes via C-N bond activation
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We have developed a nickel-catalyzed cross coupling of benzylic ammonium triflates with aryl boronic acids to afford diarylmethanes and diarylethanes. This reaction proceeds under mild reaction conditions and with exceptional functional group tolerance. Further, it transforms branched benzylic ammonium salts to diarylethanes with excellent chirality transfer, offering a new strategy for the synthesis of highly enantioenriched diarylethanes from readily available chiral benzylic amines.
- Maity, Prantik,Shacklady-Mcatee, Danielle M.,Yap, Glenn P. A.,Sirianni, Eric R.,Watson, Mary P.
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supporting information
p. 280 - 285
(2013/02/25)
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- Synthesis of diarylmethanes via metal-free reductive cross-coupling of diarylborinic acids with tosyl hydrazones
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This paper describes a practical and efficient procedure that takes advantage of diarylborinic acids as a cost-effective alternative to arylboronic acids for synthesis of diarylmethanes through metal-free reductive cross-coupling with N-tosylhydrazones of aromatic aldehydes and ketones. The procedure tolerates hydroxyl, halide, amine, and allyl functionality, complementary to the transition-metal catalyzed cross-coupling techniques.
- Li, Xijing,Feng, Yuanyuan,Lin, Lin,Zou, Gang
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p. 10991 - 10995
(2013/02/22)
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- Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
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Peroxide in, phenol out: The catalyst [-PW10O38V 2(μ-OH)2]3- showed high activity in the hydroxylation of various aromatic compounds with aqueous H2O 2. The system was regioselective, producing para-phenols from monosubstituted benzene derivatives. Furthermore, alkylarenes with reactive side-chain Ca spa 3-H bonds could be chemoselectively hydroxylated without significant formation of side-chain oxygenated products. Copyright
- Kamata, Keigo,Yamaura, Taiyo,Mizuno, Noritaka
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supporting information; experimental part
p. 7275 - 7278
(2012/08/28)
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- Dehydrative C-H alkylation and alkenylation of phenols with alcohols: Expedient synthesis for substituted phenols and benzofurans
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A well-defined cationic Ru-H complex catalyzes the dehydrative C-H alkylation reaction of phenols with alcohols to form ortho-substituted phenol products. Benzofuran derivatives are efficiently synthesized from the dehydrative C-H alkenylation and annulation reaction of phenols with 1,2-diols. The catalytic C-H coupling method employs cheaply available phenols and alcohols, exhibits a broad substrate scope, tolerates carbonyl and amine functional groups, and liberates water as the only byproduct.
- Lee, Dong-Hwan,Kwon, Ki-Hyeok,Yi, Chae S.
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supporting information; experimental part
p. 7325 - 7328
(2012/06/16)
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- Environmental implications of the surfactant effect on the photochemistry of (Substituted) 4-chlorophenols in water
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The effect of surfactants (cationic, anionic, and nonionic) on the direct photochemistry of selected chlorophenol antimicrobials in aqueous solution has been investigated. The inclusion of the starting aromatics into micelles markedly directs the reaction towards a cleaner process (mainly photoreduction), contrasting with the variety of processes observed when the irradiation is carried out in neat water. This could have some implications from the environmental point of view because such paths may be significant in natural aquatic systems. The photochemical behavior of selected chlorophenols is investigated in aqueous medium in the presence of surfactants (anionic, cationic, and nonionic). Dechlorination is efficient in every case, but in micelles, clean photoreduction results independent of the surfactant used, whereas in neat water, a complex mixture of products is obtained.
- Canevari, Veronica,Fagnoni, Maurizio,Bortolus, Pietro,Albini, Angelo
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experimental part
p. 98 - 103
(2012/01/06)
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- Br?nsted acid-catalyzed synthesis of diarylmethanes under non-genotoxic conditions
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Triflic acid and triflimide were found to efficiently catalyze the formation of a wide diversity of diarylmethanes from the non-genotoxic benzylic acetates and electron-rich arenes or heteroarenes. The reaction worked best with acetates capable of generating a stabilized benzylic cationic species. In most cases, the reactions were conveniently run in the absence of solvent under mild conditions.
- Mendoza, Oscar,Rossey, Guy,Ghosez, Léon
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experimental part
p. 2235 - 2239
(2011/05/05)
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- Mesoporous zirconium phosphate catalyzed reactions: Synthesis of industrially important chemicals in solvent-free conditions
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Mesoporous zirconium phosphate (m-ZrP) having high specific surface area and narrow pore size distributions is synthesized in basic medium using zirconium carbonate as source of zirconium. The concentration of phosphate in precursor solutions, as well as the calcination temperature, is found to influence the textural properties and acidity of synthesized m-ZrP significantly. Microscopic analysis indicates the presence of worm like pores with spherical morphology. The porous structure has remarkable thermal stability (up to 800 °C). DRIFT and NH3-TPD analysis suggest the presence of reasonable amount of Lewis and Bro?nsted acid sites. High catalytic activity of synthesized m-ZrP is observed towards Friedel-Craft (F.C.) benzylation reaction. The effect of acid strength of catalyst, reaction time, temperature and amount of catalyst towards Friedel-Craft benzylation reaction are also studied. The m-ZrP is highly active towards other acid catalyzed reactions in solvent-free conditions. The catalytic activity of m-ZrP is much higher than that of conventional layered ZrP. The catalysts were separated easily from reaction mixture, regenerated after a simple activation step and reused at least six times without significant loss in catalytic activity.
- Sinhamahapatra, Apurba,Sutradhar, Narottam,Roy, Biplab,Tarafdar, Abhijit,Bajaj, Hari C.,Panda, Asit Baran
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scheme or table
p. 22 - 30
(2011/02/23)
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- Acidic rearrangement of (benzyloxy)chalcones: A short synthesis of chamanetin
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Treatment of (benzyloxy)chalcones with trifluoroacetic acid in refluxing chloroform gave several new benzyl(hydroxy)flavanones in high yields and good regioselectivities. By using this procedure, we prepared the natural compound chamanetin in good yield from readily available reagents. Georg Thieme Verlag Stuttgart - New York.
- Sagrera, Gabriel,Seoane, Gustavo
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scheme or table
p. 4190 - 4202
(2011/03/20)
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- Chemoselectivity in the microwave-assisted solvent-free solid-liquid phase benzylation of phenols: O- versus C-alkylation
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The outcome of the solvent-free benzylation of phenol and 4-substituted phenols (such as 4-cresol and 4-chlorophenol) under MW irradiation was found to depend on the absence or presence of the base (K2CO3) and catalyst (triethylbenzy
- Keglevich, Gy?rgy,Bálint, Erika,Karsai, éva,Grün, Alajos,Bálint, Mária,Greiner, István
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p. 5039 - 5042
(2008/12/22)
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- Synthesis of substituted phenols by using the ring-closing metathesis/isoaromatization approach
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Ring-closing olefin metathesis (RCM) of 4-methylene-1,7-octadien-3-ones 2, followed by isomerization of the carbon-carbon double bond of 6-methylene-2-cyclohexenones 3 from exo to endo, produced various phenols 4. As an application of the method, the RCM/
- Yoshida, Kazuhiro,Narui, Rintaro,Imamoto, Tsuneo
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experimental part
p. 9706 - 9713
(2009/10/02)
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- New method for the reduction of benzophenones with Raney Ni-Al alloy in water
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Raney Ni-Al alloy in a dilute alkaline aqueous solution has been shown to be a powerful reducing agent, which is highly effective in the reduction of benzophenones to the corresponding hydrocarbon derivatives, in the absence of any organic solvents. Copyright Taylor & Francis Group, LLC.
- Liu, Guo-Bin,Zhao, Hong-Yun,Zhu, Jia-Da,He, Hong-Jie,Yang, Hong-Jie,Thiemann, Thies,Tashiro, Hideki,Tashiro, Masashi
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p. 1651 - 1661
(2008/09/20)
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- Chemistry of photogenerated α-phenyl-substituted o-, m-, and p-quinone methides from phenol derivatives in aqueous solution
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The enhanced photochemical reactivity of o-substituted phenols in its propensity to give o-quinone methide (o-QM) intermediates via excited state intramolecular proton transfer (ESIPT) was uncovered by Keith Yates as part of his now classic studies of photohydration of aromatic alkenes, alkynes, and related compounds. Photogeneration of QMs and the study of their chemistry along with potential biological applications are the focus of many groups. In this work, photochemical precursors to o-, m-, and p-QMs based on substituted phenols (hydroxybenzyl alcohols) and related compounds have been studied in aqueous solution as a function of pH and water content. The focus will be on QMs that are stabilized by an a-phenyl substituent, which enhances quantum yields for their formation, with the resulting QMs having longer lifetimes and easier to detect. Noteworthy is that all QM isomers can. be photogenerated with the o and m isomers being the most efficient, consistent with the Zimmerman "ortho-meta" effect. m-QMs have formal non-Kekule structures, and although they can be routinely photogenerated, are found to be most reactive. One m-QM was found, to undergo a photocondensation reaction at high pH giving rise to m-substituted oligomers. The mechanism, of QM formation in aqueous solution is believed to involve singlet excited phenols that undergo adiabatic deprotonation to give the corresponding photoexcited phenolate ion, which subsequently expels the hydroxide ion (photodehydroxylation). A pathway involving direct loss of water for the o-isomers is also possible in organic solvents.
- Diao, Li,Wan, Peter
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p. 105 - 118
(2008/09/18)
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- Zirconia-modified superacid UDCaT-5: An efficient and versatile catalyst for alkylation reactions under solvent-free conditions
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UDCaT-5, a modified version of zirconia, efficiently catalyzes alkylation of phenols with alcohols under environmentally safe, heterogeneous reaction conditions with high selectivity and in excellent yields. The high content present in UDCaT-5 with preservation of tetragonal phase of zirconia was responsible for the superactivity. Several phenolic compounds carrying either electron-sulfer releasing or electron-withdrawing substituents in the ortho, meta, and para positions afforded high yields of the products. Copyright Taylor & Francis Group, LLC.
- Yadav, Ganapati D.,Pathre, Ganesh S.
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p. 2684 - 2691
(2008/12/22)
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- NOVEL CYCLOHEXANE DERIVATIVE, PRODRUG THEREOF AND SALT THEREOF, AND THERAPEUTIC AGENT CONTAINING THE SAME FOR DIABETES
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A cyclohexane derivative having the function of reducing a blood sugar level and having preferable properties required of medicines, such as long-lasting drug activity, metabolic stability, and safety; and a medicinal composition for use in the prevention or treatment of diseases attributable to hyperglycemia, such as diabetes, e.g., insulin dependent diabetes mellitus (type 1 diabetes) or noninsulin-dependent diabetes mellitus (type 2 diabetes), complications of diabetes, and obesity. The derivative is a compound represented by the formula (I): (wherein A is -O-, -CH2-, or -NH-; n is an integer selected between 0 and 1; R6 and R7 each independently is hydrogen or C1-6 alkyl; m is an integer selected among 1-3; Q is selected among the following formulae Q1 to Q5; Ar1 is optionally substituted arylene or optionally substituted heteroarylene, provided that the heteroarylene may be bonded to an aromatic carbocycle or aromatic heterocycle to form a fused ring; and Ar2 is optionally substituted aryl or optionally substituted heteroaryl), a prodrug of the compound, or a pharmaceutically acceptable salt of either. Also provided are a medicine, a medicinal composition, or the like each containing the compound.
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- METHOD OF MAKING BENZYLATED PHENOLS
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A method of making benzylated phenols comprises contacting a phenol and a benzyl alcohol with a basic metal oxide catalyst at a temperature sufficient to maintain each of the phenol and the benzyl alcohol in a vapor phase. The phenol has at least one hydr
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Page/Page column 9-10
(2008/06/13)
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- Ionic liquids as reagent and reaction medium: Preparation of alkyl aryl ethers
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Room temperature ionic liquid, [bmIm]OH, is used as a green recyclable reaction medium and reagent for the alkylation of phenols in excellent yields. The recovered ionic liquid was reused five to six times with consistent activity.
- Mohanazadeh, Farajollah,Aghvami, Majid
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- METHOD FOR PRODUCING 2-BENZYLPHENOL COMPOUND
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[Task] Provide a process for producing a 2-benzylphenol compound easily, efficiently and selectively. [Means for Achievement] A process for producing a 2-benzylphenol compound represented by the following general formula (2) (in the formula, R1, R2, R3 and R4 may be the same or different and are each independently hydrogen atom, alkyl group or the like; and R5, R6, R7, R8 and R9 may be the same or different and are each independently hydrogen atom, alkyl group or the like), characterized by reacting, in the presence of a dehydrogenating agent, a benzylidenecyclohexanone compound represented by the following general formula (1) (in the formula, R1, R2, R3, R4, R5, R6, R7, R8 and R9 have the same definitions as given above). [Effect] A 2-benzylphenol compound substantially free from isomers can be produced from a benzylidenecyclohexanone compound (an easily obtainable raw material) selectively, efficiently and in a simple operation, under mild conditions without using any special reactor.
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- METHOD FOR PRODUCING 2-BENZYLPHENOL COMPOUND
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Disclosed is a simple method for efficiently and selectively producing a 2-benzylphenol compound. Specifically disclosed is a method for producing a 2-benzylphenol compound represented by the following general formula (2): (wherein R1, R2, R3, R4, R5, R6, R7, R8 and R9 represent the same as defined in the general formula (1) below) which is characterized by reacting a benzylidenecyclohexane compound represented by the following general formula (1): (wherein R1, R2, R3 and R4 may be the same or different and respectively represent a hydrogen atom, an alkyl group or the like; and R5, R6, R7, R8 and R9 may be the same or different and respectively represent a hydrogen atom, an alkyl group or the like) in the presence of a dehydrogenation agent. Consequently, a 2-benzylphenol compound substantially containing no isomers can be produced selectively and efficiently under mild conditions by a simple procedure using an easily-available benzylidenecyclohexane compound as the raw material without requiring a special reaction equipment.
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Page/Page column 31
(2008/06/13)
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- An effective bismuth-catalyzed benzylation of arenes and heteroarenes
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A highly efficient Bi(OTf)3-catalyzed benzylation of arenes and heteroarenes has been developed. The mild reaction conditions, high yields, operational simplicity and practicability, broad scope, and remarkably low catalyst loading render this environment friendly process an attractive approach to diarylmethane derivatives. The extension to an intramolecular variant of this procedure provides a valuable route to substituted fluorenes.
- Rueping, Magnus,Nachtsheim, Boris J.,Ieawsuwan, Winai
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p. 1033 - 1037
(2007/10/03)
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