- A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
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A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
- Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
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p. 7633 - 7640
(2021/09/22)
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- Method for hydrolyzing diarylether compound to generate aryl phenol compound
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The invention discloses a method for hydrolyzing a diarylether compound to generate an arylphenol compound. According to the method, visible light is utilized to excite a photosensitizer for catalysis. In a reaction solvent, the raw material in the formula (1) breaks a C (sp2)-O bond under the auxiliary action of acid, and hydrolysis is performed to obtain the bimolecular aryl phenol compounds in the formula (3) and the formula (4). The method can catalyze the reaction at room temperature, is green and environment-friendly, and is easy to operate; the universality is wide, the reaction yield is relatively high, and the tolerance of functional groups is strong; the synthesis method not only can realize small-scale hydrolysis conversion of various diarylether compounds, but also can realize hydrolysis of herbicidal ether, triclosan and a lignin template substrate, and even can realize large-scale hydrolysis of triclosan and the lignin template substrate to realize gram-level degradation. A new strategy is provided for recovering phenol derivatives through lignin hydrolysis, degrading pesticides and purifying wastewater containing a degerming agent or herbicide. The method has wide application prospect and use value.
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Paragraph 0082-0085
(2021/09/29)
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- Highly efficient heterogeneous V2O5@TiO2 catalyzed the rapid transformation of boronic acids to phenols
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A V2O5@TiO2 catalyzed green and efficient protocol for the hydroxylation of boronic acid into phenol has been developed utilizing environmentally benign oxidant hydrogen peroxide. A wide range of electron-donating and the electron-withdrawing group-containing (hetero)aryl boronic acids were transformed into their corresponding phenol. The methodology was also applied successfully to transform various natural and bioactive molecules like tocopherol, amino acids, cinchonidine, vasicinone, menthol, and pharmaceuticals such as ciprofloxacin, ibuprofen, and paracetamol. The other feature of the methodology includes gram-scale synthetic applicability, recyclability, and short reaction time.
- Upadhyay, Rahul,Singh, Deepak,Maurya, Sushil K.
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supporting information
p. 3925 - 3931
(2021/08/24)
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- Aryl phenol compound as well as synthesis method and application thereof
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The invention discloses a synthesis method of an aryl phenol compound shown as a formula (3). All systems are carried out in an air or nitrogen atmosphere, and visible light is utilized to excite a photosensitizer for catalyzation. In a reaction solvent, ArNR1R2 as shown in a formula (1) and water as shown in a formula (2) are used as reaction raw materials and react under the auxiliary action of acid to obtain the aryl phenol compound as shown in a formula (3). The ArNR1R2 in the formula (1) can be primary amine and tertiary amine, can also be steroid and amino acid derivatives, and can also be drugs or derivatives of propofol, paracetamol, ibuprofen, oxaprozin, indomethacin and the like. The synthesis method has the advantages of cheap and easily available raw materials, simple reaction operation, mild reaction conditions, high reaction yield and good compatibility of substrate functional groups. The fluid reaction not only can realize amplification of basic chemicals, but also can realize amplification of fine chemicals, such as synthesis of drugs propofol and paracetamol. The invention has wide application prospect and use value.
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Paragraph 0096-0099
(2021/05/12)
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- Synthetic method of m-trifluoromethylphenol
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The invention belongs to the field of organic synthesis, and particularly relates to a synthetic method of m-trifluoromethylphenol. The method comprises the following steps: (1) in a solvent, carrying out Williamson reaction on m-chlorobenzotrifluoride and tert-butyl alcohol under the catalysis of sodium hydride and metal acetate to prepare an intermediate m-trifluoromethylbenzene tert-butyl ether; (2) in a solvent, carrying out tertiary butyl removal on the m-trifluoromethyl benzene tert-butyl ether prepared in the step (1) under the action of a ZSM-5 molecular sieve to prepare the trifluoromethylphenol. The synthesis steps are simple, the cost is low, and the process is more environment-friendly.
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Paragraph 0022; 0026-0029; 0032-0034; 0037-0041
(2021/11/03)
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- Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
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The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
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Paragraph 0025-0028; 0030-0032
(2020/01/25)
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- Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
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An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
- Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
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- Aerobic photooxidative hydroxylation of boronic acids catalyzed by anthraquinone-containing polymeric photosensitizer
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We report herein the synthesis of a polymeric photosensitizer and its application in aerobic photooxidative hydroxylation of boronic acids. The polymeric photosensitizer was synthesized by the condensation of anthraquinone-2-carbonyl chloride (AQ-2-COCl) with poly (2-hydroxyethyl methacrylate) (PHEMA). The photo-oxidative hydroxylation of boronic acids using anthraquinone-containing-poly (2-hydroxyethyl methacrylate) (AQ-PHEMA) was then explored and shown to exhibit high efficiency and broad scope. Moreover, AQ-PHEMA could be easily recovered and reused for more than 20 times without significant loss of the catalytic activity.
- Chen, Yang,Ding, Aishun,Hu, Jianhua
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p. 7927 - 7932
(2020/03/11)
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- Preparation method of m-trifluoromethylphenol
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The invention discloses a preparation method of m-trifluoromethylphenol. The preparation method of the m-trifluoromethylphenol comprises the steps that (1) in a continuous flow reactor, a sulfate aqueous solution and an aqueous solution of sodium nitrite are subjected to a diazotization reaction to obtain a diazonium salt solution, wherein the sulfate aqueous solution is a mixture of an aqueous solution of sulfuric acid and m-trifluoromethyl aniline; and (2) in the continuous flow reactor, under the existence of an aromatic solvent, the diazonium salt solution obtained in the step (1) is subjected to a hydrolysis reaction to obtain the m-trifluoromethylphenol, wherein the temperature of the hydrolysis reaction is 101-200 DEG C. Through the continuous preparation method, the reaction concentration can be increased, the reaction time can be greatly shortened, production efficiency is improved, the safety risk is lowered, the yield can reach 95% or above, the purity can reach 99.5% or above, and the method has the advantages of being easy and convenient to operate, safer, more environmentally friendly, lower in cost and the like.
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Paragraph 0051-0055
(2020/03/02)
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- Method of removing protective groups of olefins under catalytic action of nickel
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The invention relates to a method of removing protective groups of olefins under the catalytic action of nickel. The method comprises following steps: dissolving olefin containing compounds into an organic solvent, carrying out reactions in the presence of a catalyst, organic ligands, bis(pinacolato)diboron, alkalis, alcohols, and water, wherein the catalyst contains nickel; after reactions, adding excess hydrochloric acid solution (1M) to adjust the pH to the acidic region, stirring the solution until the solution becomes clear; adding water and ethyl acetate to carry out extraction; washing the organic phase by saturated brine, drying the organic phase by anhydrous sodium sulfate, carrying out condensation, and adopting a 200-300 mesh silica gel column to carry out chromatographic separation to obtain compounds that contains alcohols or phenol. The provide method has the advantages that the adopted chemical reagents are common, the primary alkyl halide protective groups of olefins can be removed efficiently, and the method has a good application prospect in the field of organic synthesis and good industrial potential.
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Paragraph 0227-0230
(2019/10/04)
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- Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
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The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
- Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
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supporting information
p. 3260 - 3269
(2019/03/11)
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- Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
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Photoinduced hydroxylation of boronic acids with molecular oxygen under photocatalyst-free conditions is reported, providing a green entry to a variety of phenols and aliphatic alcohols in a highly concise fashion. This new protocol features photocatalyst-free conditions, wide substrate scope and excellent functional group compatibility.
- Xu, Yu-Ting,Li, Chen-Yuan,Huang, Xiao-Bo,Gao, Wen-Xia,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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supporting information
p. 4971 - 4975
(2019/09/30)
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- Cellulose as recyclable organocatalyst for ipso-hydroxylation of arylboronic acids
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Cellulose catalyzed oxidative hydroxylation of aryl and hetero-arylboronic acids to the corresponding phenols under metal and base free strategy has been demonstrated. The sustainable ipso-hydroxylation takes place using hydrogen peroxide as an oxidant in water under mild condition in shorter period of time. Interestingly, easy recovery and reusability of heterogeneous catalyst without significant loss in catalytic yield makes the protocol environmentally benign.
- Laskar, Khairujjaman,Paul, Subham,Bora, Utpal
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- The highly efficient air oxidation of aryl and alkyl boronic acids by a microwave-assisted protocol under transition metal-free conditions
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Molecular oxygen is the most important green-oxidant due to its excellent properties. However, the effective utilization of molecular oxygen remains a major challenge in modern chemistry. Herein, we report the development a rapid, green and efficient microwave-assisted protocol for the air oxidation of boronic acids to phenols and alcohols under transition metal-free conditions. In the presence of KOH and DMSO, high yields of the expected phenols and alcohol were obtained with microwave-assistance, and a variety of functional groups were tolerated in this procedure. Notably, this transition metal-free method represents a breakthrough in both organic synthesis and green chemistry for the oxidative hydroxylation of boronic acids to phenols and alcohols.
- Yin, Weiyan,Pan, Xizhi,Leng, Wenxi,Chen, Jian,He, Haifeng
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supporting information
p. 4614 - 4618
(2019/09/09)
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- Synthesis of phenols and aryl silyl ethers via arylation of complementary hydroxide surrogates
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Two transition-metal-free methods to access substituted phenols via the arylation of silanols or hydrogen peroxide with diaryliodonium salts are presented. The complementary reactivity of the two nucleophiles allows synthesis of a broad range of phenols without competing aryne formation, as illustrated by the synthesis of the anesthetic Propofol. Furthermore, silyl-protected phenols can easily be obtained, which are suitable for further transformations.
- Reitti, Marcus,Gurubrahamam, Ramani,Walther, Melanie,Lindstedt, Erik,Olofsson, Berit
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supporting information
p. 1785 - 1788
(2018/04/14)
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- Preparation method of m-trifluoromethylphenol
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The invention discloses a preparation method of m-trifluoromethylphenol. A preparation method of the m-trifluoromethylphenol comprises the following steps of enabling m-trifluoromethylphenol and alkali metal hydroxide and/or alkali metal alcohol to hydrolyze in an alcohol solvent under the condition of existence of a copper complex catalyst, and acidifying a reaction solution; the copper complex catalyst is selected from one or multiple of 8-copper hydroxyquinoline, 2-methyl-8-copper hydroxyquinoline, 4-methyl-8-copper hydroxyquinoline, copper acetate, and copper acetylacetonate. The preparation method has the advantages that the raw materials which can be easily purchased in industry are used for reacting, the technology is simple, the post-treatment is easy, the conditions are relativelymoderate, the pollution to environment is smaller, the m-trifluoromethylphenol with higher purity can be prepared at higher yield rate, the cost is low, and the industrialization application is realized. (The formula is shown in the description.).
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Paragraph 0059-0060
(2018/03/26)
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- METHOD FOR SYNTHESIZING PHENOL USING METAL CATALYST
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The present invention relates to a method for synthesizing phenol using a metal catalyst and, more specifically, to a method for preparing phenol, which is a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst. According to the present invention, phenol, as a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst, can be synthesized with high yield. Also, various phenols having substituents can be synthesized.COPYRIGHT KIPO 2017
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Paragraph 0058; 0061
(2017/10/26)
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- Preparation method of 3-hydroxyphenyl trifluoromethyl ether
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The invention provides a preparation method of 3-hydroxyphenyl trifluoromethyl ether. The preparation method comprises the following steps: taking 4-trifluoromethoxyaniline as a raw material; and successively carrying out acetylation, nitrification, deacetylation, deaminizating, reduction and hydrolysis reaction on the 4-trifluoromethoxyaniline to obtain the 3-hydroxyphenyl trifluoromethyl ether. The preparation method is high in yield of products, simple to operate and low in production cost; and industrialization is facilitated.
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- Method for continuous flow synthesis of phenol-based compound
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The present invention provides a method for continuous flow synthesis of a phenol-based compound represented by a formula (III), wherein the method is performed in two static mixers, a tubular reactor and an oil-water separator, wherein the two static mixers, the tubular reactor and the oil-water separator are sequentially connected in series. The method comprises that an acid solution and an aniline compound represented by a formula (I) are pumped into the static mixer A; the mixture of the acid solution and the compound represented by the formula (I) flows out from the static mixer A and flows into the static mixer B connected to the static mixer A; a sodium nitrite solution is pumped into the static mixer B, and a reaction is performed to produce a diazonium salt solution represented by a formula (II); and the solution represented by the formula (II) flows out from the static mixer B, is pumped into the tubular reactor connected to the static mixer B, and then into the oil-water separator connected to the tubular reactor, and the water phase is separated to obtain the compound represented by the formula (III). According to the present invention, the method has characteristics of short reaction time, solvent saving and high yield, and can well solve the problems in the synthesis of the phenol-based compound through diazotization hydrolysis in the intermittent kettle type reactor. The formulas (I), (II) and (III) are defined in the specification.
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Paragraph 0031; 0032; 0033; 0034; 0035; 0336; 0037-0048
(2017/07/21)
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- Preparation method of m-trifluoromethylphenol
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The invention discloses a preparation method of m-trifluoromethylphenol, and belongs to the technical field of organic synthesis. The method comprises the following steps: diazotizing a raw material m-aminotrifluorotoluene to obtain a diazonium reaction solution, hydrolyzing the diazonium reaction solution to synthesize m-trifluoromethylphenol, and post-processing the m-trifluoromethylphenol to obtain a highly-pure m-trifluoromethylphenol product. The method has the advantages of simple process, low production cost and suitableness for industrial production.
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Paragraph 0024-0035
(2017/08/31)
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- Copper-Catalyzed Hydroxylation of (Hetero)aryl Halides under Mild Conditions
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The combination of Cu(acac)2 and N,N′-bis(4-hydroxyl-2,6-dimethylphenyl)oxalamide (BHMPO) provides a powerful catalytic system for hydroxylation of (hetero)aryl halides. A wide range of (hetero)aryl chlorides bearing either electron-donating or -withdrawing groups proceeded well at 130 °C, delivering the corresponding phenols and hydroxylated heteroarenes in good to excellent yields. When more reactive (hetero)aryl bromides and iodides were employed, the hydroxylation reactions completed at relatively low temperatures (80 and 60 °C, respectively) at low catalytic loadings (0.5 mol % Cu).
- Xia, Shanghua,Gan, Lu,Wang, Kailiang,Li, Zheng,Ma, Dawei
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supporting information
p. 13493 - 13496
(2016/10/31)
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- A Mild Strategy for the Preparation of Phenols via the Ligand-Free Copper-Catalyzed O-Arylation of para -Toluenesulfonic Acid
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A facile and simple ligand-free copper-catalyzed reaction to synthesize substituted phenols is reported. The reaction presumably proceeds via an O-arylsulfonate intermediate that is hydrolyzed to afford good to excellent yields of up to 88%. This protocol provides an alternative to existing reports which use strong hydroxide salts as the direct hydroxylation partner. Demonstrating a wide substrate scope and functional group tolerance, this protocol can also be applied to inexpensive and commercially available carboxylic acids to yield phenols.
- Tan, Bryan Yong-Hao,Teo, Yong-Chua
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supporting information
p. 1814 - 1819
(2016/07/16)
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- Synthesis and biological activity of abscisic acid esters
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Abstract 16 ABA esters including 11 new compounds were prepared by two different esterification routes. All the structures of ABA esters were confirmed by 1H NMR, 13C NMR and HRMS. Their biological activity and hydrolysis stability were investigated. Fortunately, there were 15 and 9 compounds which displayed much better or nearly the same inhibition activity for rice seedling growth and Arabidopsis thaliana seed germination compared to ABA, respectively. Especially, compounds 2d and 2g showed better biological activities than ABA in the three tests. Moreover, we found that chemical hydrolysis ability of the esters in vitro had little relationship to their biological activity.
- Wan, Chuan,Zhang, Yuanzhi,Yang, Dongyan,Han, Xiaoqiang,Li, Xiuyun,Li, Hong,Xiao, Yumei,Qin, Zhaohai
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p. 267 - 272
(2015/06/22)
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- Solvent-free one-step photochemical hydroxylation of benzene derivatives by the singlet excited state of 2,3-dichloro-5,6-dicyano-p-benzoquinone acting as a super oxidant
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Photoinduced hydroxylation of neat deaerated benzene to phenol occurred under visible-light irradiation of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), which acts as a super photooxidant in the presence of water. Photocatalytic solvent-free hydroxylation of benzene derivatives with electron-withdrawing substituents such as benzonitrile, nitrobenzene, and trifluoromethylbenzene used as neat solvents has been achieved for the first time by using DDQ as a super photooxidant to yield the corresponding phenol derivatives and 2,3-dichloro-5,6-dicyanohydroquinone (DDQH2) in the presence of water under deaerated conditions. In the presence of dioxygen and tert-butyl nitrite, the photocatalytic hydroxylation of neat benzene occurred with DDQ as a photocatalyst to produce phenol. The photocatalytic reactions are initiated by oxidation of benzene derivatives with the singlet and triplet excited states of DDQ to form the corresponding radical cations, which associate with benzene derivatives to produce the dimer radical cations, which were detected by the femto- and nanosecond laser flash photolysis measurements to clarify the photocatalytic reaction mechanisms. Radical cations of benzene derivatives react with water to yield the OH-adduct radicals. On the other hand, DDQC?- produced by the photoinduced electron transfer from benzene derivatives reacts with the OH-adduct radicals to yield the corresponding phenol derivatives and DDQH2. DDQ is recovered by the reaction of DDQH2 with tert-butyl nitrite when DDQ acts as a photocatalyst for the hydroxylation of benzene derivatives by dioxygen.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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supporting information
p. 2855 - 2861
(2015/02/05)
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- The Hydroxylation of Aromatics with Oxygen by Vanadium Catalysts Supported on N-doped Carbon Materials
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Vanadium catalysts supported on N-doped carbon materials (CN) were prepared and the catalyst VOSiW showed high activity for the hydroxylation of various aromatics with O2. Aromatics with electron-withdrawing groups such as CN, NO2, COOH, CF3, COCH3 and aromatic halides (F, Cl and Br) were oxygenated to the corresponding phenols in considerable yields. The CN materials were not only indispensable for the reusability of the vanadium catalyst VOSiW, but also favorable to the high catalytic activity. The VOSiW catalyst is ready for the hydroxylation of aromatics with O2 as both V4+ and V5+ species are coexisted in the VOSiW catalyst.
- Li, Yan,Li, Bing,Geng, Longfei,Wang, Jun,Wang, Yong,Huang, Jun
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p. 1014 - 1021
(2015/08/04)
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- Biosilica as an efficient heterogeneous catalyst for ipso-hydroxylation of arylboronic acids
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A mild and efficient protocol for the conversion of arylboronic acids to phenol via ipso-hydroxylation has been developed using aqueous hydrogen peroxide as oxidant and biosilica as heterogeneous catalyst. The recyclability of the catalyst is also evaluated and could be reused up to six consecutive cycles without a significant loss in catalytic activity.
- Mahanta, Abhijit,Adhikari, Pooja,Bora, Utpal,Thakur, Ashim Jyoti
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supporting information
p. 1780 - 1783
(2015/03/30)
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- Catalysis by mont K-10 supported silver nanoparticles: A rapid and green protocol for the efficient ipso-hydroxylation of arylboronic acids
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A mild and efficient methodology has been developed for the ipso-hydroxylation of arylboronic acids using montmorillonite K-10 supported silver nanoparticles (AgNPs) as catalyst and aqueous H2O2 as oxidant. The reactions were performed at room temperature within short reaction time under solvent- and base-free conditions. This catalyst shows good reusability.
- Begum, Tahshina,Gogoi, Ankur,Gogoi, Pradip K.,Bora, Utpal
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-
- Organic hypervalent iodine(III) catalyzed ipso-hydroxylation of aryl- and alkylboronic acids/esters
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An organo-hypervalent iodine(III) catalyzed highly efficient methodology for ipso-hydroxylation of diversely functionalized aryl- and alkylboronic acids/esters has been developed using NaIO4 as a co-oxidant. This protocol is also applicable to N-heterocyclic boronic acids and esters. Further mechanistic studies revealed that the organoboronic acid (an electron demanding moiety) is acting as a nucleophile in the presence of hypervalent iodine for hydroxylation reactions. In summary, this is the first Letter of a generalized route for organic hypervalent iodine(III) catalyzed hydroxylation of organoboronic compounds.
- Chatterjee, Nachiketa,Goswami, Avijit
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supporting information
p. 1524 - 1527
(2015/03/14)
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- Reaction of 1,2-difunctionalized ethanes with aryl iodides in copper-catalyzed cross-coupling: Application to synthesis of phenols
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A series of 1,2-difunctionalized ethanes, such as ethylene glycol, 2-aminoethanol, 1,2-diaminoethane, 2-dimethylaminoethanol N',N'-dimethylethane-1,2-diamine, were investigated to test the reactivity with aryl iodides in the presence of copper catalysts. Under the reaction conditions, they produce the various Cheteroatom cross-coupled products. Interestingly, ethylene glycol and 2-dimethylaminoethanol afforded mainly the phenolic compounds while the others produced different cross-coupled products. Although ethylene glycol and 2-dimethylaminoethanol resulted in the same product, their behaviors in the reaction were quite different: ethylene glycol appears to mostly act as the ligand and 2-dimethylaminoethanol appears to serve as both the ligand and reactant. This finding led to a copper-catalyzed synthesis of phenols using either ethylene glycol or 2-dimethylaminoethanol, which can be applied to a variety of aryl iodides, providing an alternative synthetic route to phenols.
- Kim, Jihye,Battsengel, Oyunsaikhan,Liu, Yajun,Chae, Junghyun
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supporting information
p. 2833 - 2840
(2016/02/05)
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- Hydrolysis of diazonium salts using a two-phase system (CPME and water)
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A new method for the hydrolysis of diazonium salts, without the formation of tar, was developed. A two-phase system consisting of cyclopentyl methyl ether (CPME) and water is very effective for the hydrolysis of diazonium salts. Using this solvent system, the diazonium salt prepared from 3-(4-nitrophenoxy)aniline gave 3-(4-nitrophenoxy)phenol in high yield (96%) within 20 min. The synthesized phenol is an industrially important raw material in polymer syntheses. Furthermore, the use of the present two-phase system of CPME and water successfully brought about the efficient conversions of several m-substituted anilines into the corresponding m-substituted phenols. This is the first example of hydrolysis of diazonium salts using the two-phase system (CPME and water).
- Taniguchi, Toshihide,Imoto, Mitsutaka,Takeda, Motonori,Nakai, Takeo,Mihara, Masatoshi,Iwai, Toshiyuki,Ito, Takatoshi,Mizuno, Takumi,Nomoto, Akihiro,Ogawa, Akiya
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p. 411 - 416
(2018/01/18)
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- Structure-reactivity Relationships as Probes to Acetylcholinesterase Inhibition Mechanisms by Aryl Carbamates. II. Hammett-Taft Cross-interaction Correlations
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Substituted phenyl-N-butyl carbamates (1) and p-nitrophenyl-N-substituted carbamates (2) are characterized as "pseudo-pseudo-substrate" inhibitors of acetylcholinesterase. Since the inhibitors protonate in pH 7.0 buffer solution, the virtual inhibition co
- Lin, Gialih
-
p. 423 - 429
(2015/02/05)
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- A novel sustainable strategy for the synthesis of phenols by magnetic CuFe2O4-catalyzed oxidative hydroxylation of arylboronic acids under mild conditions in water
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A novel sustainable strategy for the synthesis of phenols has been developed using inexpensive, readily available, air-stable, and recyclable CuFe2O4 nanoparticles as the catalyst, and the corresponding substituted phenols were obtained in moderate to good yields by oxidative hydroxylation of arylboronic acids in water. Importantly, a ligand or an additive was not necessary. The catalyst was completely recoverable with an external magnet and could be reused six times without significant loss of catalytic activity.
- Yang, Daoshan,An, Baojuan,Wei, Wei,Jiang, Min,You, Jinmao,Wang, Hua
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supporting information
p. 3630 - 3634
(2014/05/20)
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- Hydroxylation of aryl- and alkylboronic acids/esters mediated by iodobenzene diacetate - An avenue for using organoboronic acids/esters as nucleophiles for hydroxylation reactions
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A metal free, mild, and highly efficient methodology for ipso-hydroxylation of diversely functionalized aryl- and alkylboronic acids/esters mediated by iodobenzene diacetate (DAIB) under ambient temperature has been developed. This protocol is also applicable to N-heterocyclic boronic acids and esters. In the course of understanding the mechanism of this protocol, it is anticipated that organoboronic acid/ester, even being an electron demanding moiety, is acting as a nucleophile in the presence of DAIB for the hydroxylation reaction.
- Chatterjee, Nachiketa,Chowdhury, Hrishikesh,Sneh, Kumar,Goswami, Avijit
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supporting information
p. 172 - 174
(2015/02/02)
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- Continuous-flow hydroxylation of aryl iodides promoted by copper tubing
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A simple and ligand-free synthesis of phenols from the corresponding aryl iodides in a continuous-flow system is described. The reaction is complete in only 4 to 20 minutes when heated between 150 to 165 °C in a reactor consisting of a commercially available copper coil. An example of trapping of the phenoxide in situ is also shown.
- Cyr, Patrick,Charette, André B.
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supporting information
p. 1409 - 1412
(2014/06/23)
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- Ipso-hydroxylation of arylboronic acids and boronate esters by using sodium chlorite as an oxidant in water
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A facile and efficient procedure for the ipso-hydroxylation of arylboronic acids to phenols in water was developed. A series of electron-rich and electron-deficient arylboronic acids were smoothly ipso-hydroxylated with this protocol to afford products in excellent yields. Moreover, the protocol is amenable to boronate esters. In most cases, the phenolic products were obtained in pure form without any chromatographic purification. An efficient procedure for the ipso-hydroxylation of arylboronic acids to phenols in water is reported. A wide range of electronically varied boronic acids are smoothly ipso-hydroxylated with this protocol, which is amenable to boronate esters. The reaction strategy is facile and clean, and the products are obtained in pure form and do not require chromatographic purification. Copyright
- Gogoi, Pranjal,Bezboruah, Pranjal,Gogoi, Junali,Boruah, Romesh C.
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supporting information
p. 7291 - 7294
(2013/11/19)
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- Efficient cleavage of alkyl aryl ethers using an ionic liquid under microwave irradiation
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A highly reliable dealkylation protocol of alkyl aryl ethers, whose alkyl groups are longer than methyl group, has been developed. We report that various ethyl, n-propyl, and benzyl aryl ethers are successfully cleaved using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide, [bmim][Br], under microwave irradiation. Despite many characteristics such as lower cost and less toxicity of the alkylating agents, and greater hydrophobicity of the products, longer alkyl ethers have been significantly less exploited than methyl ethers, probably due to more difficulty in the deprotection step. Since it has the same advantages as the demethylation method developed by this group including mild conditions, short reaction time, and small use of the ionic liquids, the dealkylation protocol can greatly encourage the broader use of longer alkyl groups in the protection of phenolic groups. As with our previous study of demethylation using [bmim][Br], the microwave irradiation is crucial for the deprotection of longer alkyl aryl ethers. Unlike the conventional heating, which causes either low conversion or decomposition, the microwave irradiation seems to more effectively provide energy to cleave the ether bonds and therefore suppresses the undesired reactions.
- Park, Se Kyung,Battsengel, Oyunsaikhan,Chae, Junghyun
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supporting information
p. 174 - 178
(2013/08/24)
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- Reductive cleavage of aryl O-carbamates to phenols by the Schwartz reagent. Expedient link to the directed ortho metalation strategy?
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A general, mild, and efficient method for the reductive cleavage of aryl O-carbamates to phenols, 1 → 2 using the Schwartz reagent is reported. The method is selective, tolerating a large number of functional groups; may be carried out by direct or by an economical in situ procedure; and, notably, establishes a synthetic connection to the directed ortho metalation strategy (Figure 1) allowing new entries into difficult to prepare contiguously substituted aromatics and heteroaromatics.
- Morin, Justin,Zhao, Yigang,Snieckus, Victor
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supporting information
p. 4102 - 4105
(2013/09/12)
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- Pd2dba3/Bippyphos: A robust catalyst system for the hydroxylation of aryl halides with broad substrate scope
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A mixture of tris(dibenzylideneacetone)dipalladium(0) (Pd 2dba3) and 5-(di-tert-butylphosphino)-1′,3′, 5′-triphenyl-1′H-[1,4′]bipyrazole (Bippyphos) is shown to be a robust and efficient catalyst system for the hydroxylation of structurally diverse (hetero)aryl halides under mild conditions and with broad substrate scope. Included in this reactivity survey is the successful synthesis of substituted benzofurans and related heteroatomic derivatives, which are formed via the hydroxylation of 2-haloalkynylarenes. Notably, a significant number of the reactions reported herein proceed at room temperature, and we have demonstrated that it is possible to conduct reactions on the benchtop under air using unpurified solvents with negligible loss in reactivity versus related transformations conducted under inert atmosphere conditions. We also report herein the first crystallographically characterized (Bippyphos)Pd(II) complex, which confirms the ability of this synthetically useful ligand to adopt a bidentate binding motif in a manner similar to Buchwald's biarylphosphine ligand class. Copyright
- Lavery, Christopher B.,Rotta-Loria, Nicolas L.,McDonald, Robert,Stradiotto, Mark
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supporting information
p. 981 - 987
(2013/05/08)
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- Aerobic oxidative heck/dehydrogenation reactions of cyclohexenones: Efficient access to meta-substituted phenols
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Jockeying for the (meta)position: A new dicationic palladium(II) catalyst, employing a 6,6′-dimethyl-2,2′-bipyridine ligand, promotes both the aerobic oxidative Heck coupling and dehydrogenation reactions of cyclohexenones. These reactions may be combined in a one-pot sequence to enable the straightforward synthesis of meta-substituted phenols (see scheme). Copyright
- Izawa, Yusuke,Zheng, Changwu,Stahl, Shannon S.
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supporting information
p. 3672 - 3675
(2013/04/23)
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- Base-catalyzed dehydration of 3-substituted benzene cis -1,2-dihydrodiols: Stabilization of a cyclohexadienide anion intermediate by negative aromatic hyperconjugation
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Evidence that a 1,2-dihydroxycyclohexadienide anion is stabilized by aromatic "negative hyperconjugation" is described. It complements an earlier inference of "positive" hyperconjugative aromaticity for the cyclohexadienyl cation. The anion is a reactive intermediate in the dehydration of benzene cis-1,2-dihydrodiol to phenol. Rate constants for 3-substituted benzene cis-dihydrodiols are correlated by σ- values with = 3.2. Solvent isotope effects for the reactions are kH2O/kD 2O = 1.2-1.8. These measurements are consistent with reaction via a carbanion intermediate or a concerted reaction with a "carbanion-like" transition state. These and other experimental results confirm that the reaction proceeds by a stepwise mechanism, with a change in rate-determining step from proton transfer to the loss of hydroxide ion from the intermediate. Hydrogen isotope exchange accompanying dehydration of the parent benzene cis-1,2-dihydrodiol was not found, and thus, the proton transfer step is subject to internal return. A rate constant of ~1011 s-1, corresponding to rotational relaxation of the aqueous solvent, is assigned to loss of hydroxide ion from the intermediate. The rate constant for internal return therefore falls in the range 1011-1012 s -1. From these limiting values and the measured rate constant for hydroxide-catalyzed dehydration, a pKa of 30.8 ± 0.5 was determined for formation of the anion. Although loss of hydroxide ion is hugely exothermic, a concerted reaction is not enforced by the instability of the intermediate. Stabilization by negative hyperconjugation is proposed for 1,2-dihydroxycyclohexadienide and similar anions, and this proposal is supported by additional experimental evidence and by computational results, including evidence for a diatropic ("aromatic") ring current in 3,3-difluorocyclohexadienyl anion.
- Kudavalli, Jaya Satyanarayana,Rao, S. Nagaraja,More Oferrall, Rory A.,Bean, David E.,Fowler, Patrick W.,Sharma, Narain D.,Boyd, Derek R.,Kamerlin, Shina Caroline Lynn,Keeffe, James R.,Gronert, Scott
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supporting information
p. 14056 - 14069,14
(2020/08/31)
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- Copper-catalyzed trifluoromethylation of aryl boronic acids using a CF 3+ reagent
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A copper-catalyzed process for trifluoromethylation of aryl, heteroaryl, and vinyl boronic acids has been developed. The reaction is conducted under mild conditions and shows tolerance to moisture and a variety of functional groups.
- Xu, Jun,Luo, Dong-Fen,Xiao, Bin,Liu, Zhao-Jing,Gong, Tian-Jun,Fu, Yao,Liu, Lei
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supporting information; experimental part
p. 4300 - 4302
(2011/06/21)
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- Palladium-catalyzed mono-α-arylation of acetone with aryl halides and tosylates
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We report the first example of selective Pd-catalyzed mono-α- arylation of acetone employing aryl chlorides, bromides, iodides, and tosylates. The use of appropriately designed P,N-ligands proved to be the key to controlling the reactivity and selectivity. The reaction affords good yields with substrates containing a range of functional groups at modest Pd loadings using Cs2CO3 as the base and employing acetone as both a reagent and the solvent.(Figure Presented)
- Hesp, Kevin D.,Lundgren, Rylan J.,Stradiotto, Mark
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body text
p. 5194 - 5197
(2011/06/10)
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- Microwave-assisted demethylation of methyl aryl ethers using an ionic liquid
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An efficient demethylation of methyl aryl ethers using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]) has been developed. Methyl aryl ethers are successfully cleaved by the halide anion of [bmim][Br], without aid of any other activating agents. In this reaction, microwave irradiation was found to be crucial for the effective conversion. The newly developed protocol is a very attractive green chemical process as it utilizes minimal amount of cleaving reagents and does not require additional activating agents or solvents. Under the conditions described herein, a broad range of methyl aryl ethers were converted to the corresponding phenolic compounds in moderate to excellent yields in a short time. Georg Thieme Verlag Stuttgart New York.
- Park, Jiyeon,Chae, Junghyun
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experimental part
p. 1651 - 1656
(2010/08/22)
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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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supporting information; experimental part
p. 976 - 978
(2010/07/10)
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- The Ever-surprising chemistry of boron: Enhanced acidity of phosphine·boranes
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The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
- Hurtado, Marcela,Yanez, Manuel,Herrero, Rebeca,Guerrero, Andres,Juan Z. Davalos,Jose-Luis, M. Abboud,Khater, Brahim,Guillemin, Jean-Claude
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supporting information; experimental part
p. 4622 - 4629
(2009/12/29)
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- Substituent effects on the rate constants for the photo-claisen rearrangement of allyl aryl ethers
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The photochemistry of 11 substituted allyl 4-X- and 3-X-aryl ethers 3 (ArOCH2-CH=CH2) has been examined in both methanol and cyclohexane as solvents. The ethers react by the photo-Claisen rearrangement to give allyl substituted phenols as the major primary photoproducts, as expected from the well-established radical pair mechanism. The excited singlet state properties (absorption spectra, fluorescence spectra, fluorescence quantum yields, and singlet lifetimes) were compared with a parallel set of unreactive 4-X- and 3-X-anisoles 4. The excited-state properties of three substituted 4-X-aryl 4-(1-butenyl) ethers 14 (ArOCH2CH2-CH=CH2) were also examined. The model compounds 4 and the reactive allyl ethers 3 have essentially identical rate constants for the excited-state processes with the exception of khoms, the rate constant for homolytic cleavage from S1 of the allyl ethers to give the radical pair. The difference between the fluorescence quantum yields and/or singlet lifetimes for 3 and 4 were used to obtain values of khoms for all of the allyl ethers. These values exhibit a large substituent effect, spanning almost 2 orders of magnitude with electron-donating groups (CH3O, CH3) accelerating the reaction and electron-withdrawing ones (CN, CF3) slowing it down. The parallel range of rate constants observed in both methanol and cyclohexane indicates that ion pairs are not important intermediates in these rearrangements. Quantum yields of reaction (Φr) for several of the more reactive ethers demonstrate that neither these values nor rate constants of reaction (khomr) derived from them are reliable measures of the actual excited-state process. In fact, the khomr values are significantly lower than the khoms ones, indicating that the radical pairs undergo recombination to generate starting material. Finally, the khoms rate constants were found to parallel a trend for the change in bond dissociation energy (ΔBDE) for the O-C (allyl) bond of the allyl ethers, indicating that other possible substituent effects are of minor importance.
- Pincock, Alexandra L.,Pincock, James A.,Stefanova, Roumiana
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p. 9768 - 9778
(2007/10/03)
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- Sulphonamide derivatives
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The present invention relates to the potentiation of glutamate receptor function using certain sulphonamide derivatives. It also relates to novel sulphonamide derivatives, to processes for their preparation and to pharmaceutical compositions containing them.
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- Photochemistry of aryl tert-butyl ethers in methanol: The effect of substituents on an excited state cleavage reaction
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The photolysis of a set of 10 substituted aryl tert-butyl ethers, 8a-j, in methanol gave, as the major product, the corresponding phenol along with tert-butyl-substituted phenols resulting from photo-Fries reaction. The corresponding 4-cyanophenyl 1-adamantyl ether, 9, also gave 1-meth-oxyadamantane 16 (16%), indicating that, at least for this ether, some of the products were ion-derived. Quenching studies with 2,3-dimethylbutadiene for the tert-butyl ethers indicated that these reactions were occurring from the singlet excited state. Rate constants for the reaction, obtained from quantum yields and singlet lifetimes, were found to correlate reasonably well with σhv values, ρ = -0.77 (r = 0.975), a result that is unexpected for a reaction where the polarity of the bond breaking in the transition state is expected to be -O(δ-)···C(δ+).
- DeCosta,Bennett,Pincock,Pincock,Stefanova
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p. 4162 - 4168
(2007/10/03)
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- Preparation of aromatic fluorides: Facile photo-induced fluorinative decomposition of arenediazonium salts and their related compounds using pyridine-nHF
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By employing pyridine-nHF solution, the photo-induced fluorinative decomposition of arenediazonium salts (ArN2BF4) (fluoro-dediazoniation) and the related compounds, such as quinonediazides and triazenes, has been successfully carried out to produce the corresponding aromatic fluorides (ArF) in good yields. The rate in the fluoro-dediazoniation of para-substituted ArN2BF4 in pyridine-nHF solution did not obey the classical Hammett equation but conformed well to Taft's treatment [dual substituent parameter relationships (DSP)]. In the thermal fluoro-dediazoniation of ArN2BF4 the rate of reaction was significantly influenced by the substituents in the substrates. On the contrary, only a slight effect by the substituents was observed on the rate of the photo-induced fluoro-dediazoniation of ArN2BF4.
- Sawaguchi, Masanori,Fukuhara, Tsuyoshi,Yoneda, Norihiko
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p. 127 - 133
(2007/10/03)
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- Kinetics and mechanisms of the photolytic and OH° radical induced oxidation of fluorinated aromatic compounds in aqueous solutions
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Laboratory experiments with H2O2/UV oxidation processes and photolysis at 253.7 nm wavelength have been carried out on dilute aqueous solutions (C0 = 0.1 to 3.0 mM) of trifluorobenzene derivatives (1,3,5-trifluorobenzene, 1,2,3 and 1,2,4-trifluorobenzene) and of α,α,α-trifluorotoluene in the presence and in the absence of dissolved oxygen. The analyses of fluoride ions content during the oxidation experiments showed that the first steps lead to the production of about 2 mol of F-/mol of trifluorobenzene decomposed and of 1 mol of F-/mol of trifluorotoluene decomposed. Kinetic studies lead to the determination of the quantum yield for the photolysis of 1,3,5-trifluorobenzene, 1,2,3 and 1,2,4-trifluorobenzene (Φ = 0.011, 0.010 and 0.015 respectively), and of trifluorotoluene (Φ = 0.015). The rate constants for the reaction of hydroxyl radicals with these molecules, determined under specific experimental conditions, were found to range from 3.7 109 to 4.9 109 M-1.s-1). GC/MS analyses carried out on extracts at different irradiation time (UV, H2O2/UV) lead to the identification of numerous by-products from trifluorobenzene and trifluorotoluene. They consist mostly in hydroxylated and dehalogenated compounds. Dimers have also been observed during photolysis. Moreover, experiments carried out under oxygen limiting conditions revealed the formation of other compounds. For each case studied, a detailed mechanism involving radical intermediates and the different reaction sequences is proposed.
- Karpel vel Leitner,Gombert,Ben Abdessalem,Dore
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p. 893 - 906
(2007/10/03)
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