- Catalytic C–O bond cleavage in a β-O-4 lignin model through intermolecular hydrogen transfer
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A base-free and redox neutral approach for the selective breaking of aryl ether bond (C–O) contained by a lignin model compound mimicking a β-O-4 linkage is reported. A palladium loaded metal-organic framework (MOF) was used as a catalyst for this purpose. The reaction proceeds through dehydrogenation of benzylic alcohol moiety followed by the hydrogenolysis of the ether bonds. Therefore, no external hydrogen source is required for the reaction to take place.
- Ahsan Usman, Muhammad,Naeem, Maham,Saeed, Muhammad,Zaheer, Muhammad
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- A practical method for preparation of phenols from arylboronic acids catalyzed by iodopovidone in aqueous medium
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A novel and efficient strategy for the ipso-hydroxylation of arylboronic acids to phenols has been developed using inexpensive, readily available, air-stable water-soluble povidone iodine as catalyst and aqueous hydrogen peroxide as oxidizing agent. The reactions were performed at room temperature under metal-, ligand- and base-free condition in a short reaction time. The corresponding substituted phenols were obtained in moderate to good yields by oxidative hydroxylation of arylboronic acids in aqueous medium.
- Dong, Bin,Ke, Yanxiong,Lu, Guangying,Ren, Jiangmeng,Ren, Yaoyao,Zeng, Bu-Bing,Zhou, Bin
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- Trichloroacetonitrile as an efficient activating agent for the: Ipso -hydroxylation of arylboronic acids to phenolic compounds
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A metal-free and base-free Cl3CCN mediated method was developed for the ipso-hydroxylation of aryl boronic acids to their corresponding phenols, which was promoted by a key unstable Lewis adduct intermediate. This transformation has broad functional group tolerance, and late-stage functionalization was successful as well. After simple investigation, two pathways (radical/ionic mechanism) were suggested, and the beneficial action of blue light needs to be further studied.
- Fang, Yuanding,Zhao, Rong,Yao, Yuan,Liu, Yang,Chang, Denghu,Yao, Ming,Shi, Lei
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p. 7558 - 7563
(2019/08/20)
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- Solar-driven conversion of arylboronic acids to phenols using metal-free heterogeneous photocatalysts
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Solar-driven conversion of arylboronic acids to phenols was achieved by employing graphitic carbon nitride (g-C3N4) as heterogeneous photocatalyst, where [rad]O2? was the main active species. By loading g-C3N4 onto the easy weaving low melting point sheath-core composite polyester fibers (LMPET), g-C3N4-based artificial photosynthetic catalytic fabric (g-C3N4/LMPET) with a large light receiving area was prepared. It displayed the efficient conversion of arylboronic acid and excellent recycling performance. This system offers more possibilities to construct an artificial photosynthetic system with excellent solar-to-chemicals conversion efficiency.
- Xu, Tiefeng,Lu, Wangyang,Wu, Xiao-Feng,Chen, Wenxing
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- A catalytic oxidation fragrant boron class compound preparing phenol method (by machine translation)
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The invention discloses a method for catalytic oxidation of phenolic compounds fragrant boron class compound synthesis method, the flux in the solvent in the aqueous solution, under the action of alkali, adding hydrazine hydrate or acid hydrazides catalyst, catalytic oxidation fragrant boron class compound directly for the preparation of phenolic compound. The invention of the method of preparation of the phenol compound, the catalyst is a cheap hydrazine hydrate or hydrazine compound, the oxidizing agent is atmospheric pressure of air or oxygen, the reaction does not need good and activeness metal catalyst, is extensive and stable substrate, substrate-sensitive functional group compatibility good and wide range of application. In the optimized under the reaction conditions, the yield of the target product separation up to 99%. (by machine translation)
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Paragraph 0027; 0041; 0042
(2017/08/08)
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- An efficient and chemoselective deprotection of aryl tert-butyldimethylsilyl (TBDMS) ethers by NaCN
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Phenolic tert-butyldimethylsilyl (TBDMS) ethers can be deprotected to yield phenols in excellent yield using sodium cyanide (NaCN) as catalyst in ethanol. The deprotectation of various phenolic TBDMS ethers were found to be very convenient, fast, high yielding and chemoselective.
- Qiao, Xue-Jun,Hou, Xiao,Fang, Wu-Hong,Bao, Xue-Fei,Chen, Guo-Liang
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p. 899 - 904
(2016/05/19)
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- Modification of an Enzyme Biocatalyst for the Efficient and Selective Oxidative Demethylation of para-Substituted Benzene Derivatives
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The bacterial CYP199A4 enzyme is able to oxidise a narrow range of aromatic acids, which includes 4-methoxybenzoic acid, efficiently. A serine 244 to aspartate variant was identified with enhanced activity for a wide range of para-methoxy-substituted benzenes. Substrates in which the acidic benzoic acid moiety is replaced with a phenol and the amide, aldehyde and bromide analogues were all oxidised with high activity by the S244D mutant (product formation rate >600 nmol nmolCYP ?1 min?1) with turnover numbers of up to 20 000. If the carboxylate moiety was modified to a nitro, ketone, boronic acid, hydroxymethyl or nitrile group, these substrates were also oxidised at a significantly higher activity by S244D than the wild-type enzyme. 3,4-Dimethoxybenzaldehyde was demethylated selectively and oxidatively to 3-methoxy-4-hydroxybenzaldehyde by the S244D mutant 84-fold more rapidly than with the wild-type enzyme. CYP199A4 would have applications in the catalytic regioselective oxidative demethylation of suitably substituted benzene substrates under mild conditions and in the presence of more oxidatively sensitive functional groups, such as an aldehyde.
- Chao, Rebecca R.,Lau, Ian C.-K.,De Voss, James J.,Bell, Stephen G.
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p. 3626 - 3635
(2016/12/14)
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- PROCESS FOR THE PREPARATION OF 4-SUBSTITUTED-1-(TRIFLUOROMETHOXY)BENZENE COMPOUNDS
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The present invention provides the process for the preparation of 4-substituted-1- (trifluoromethoxy) benzene compounds..
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Page/Page column 9
(2016/09/22)
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- Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide
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Fe2O3 catalyzed rapid oxidation of arylboronic acids to obtain phenols in excellent yields (90-95%) in the presence of atmospheric oxygen under solar VIS-light irradiation using α-Fe2O3 as a catalyst in ligand- and base-free conditions is presented.
- Sawant, Sanghapal D.,Hudwekar, Abhinandan D.,Aravinda Kumar,Venkateswarlu, Vunnam,Singh, Parvinder Pal,Vishwakarma, Ram A.
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p. 811 - 814
(2015/03/03)
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- Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide
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Fe2O3 catalyzed rapid oxidation of arylboronic acids to obtain phenols in excellent yields (90-95%) in the presence of atmospheric oxygen under solar VIS-light irradiation using α-Fe2O 3 as a catalyst in ligand- and base-free conditions is presented.
- Sawant, Sanghapal D.,Hudwekar, Abhinandan D.,Aravinda Kumar,Venkateswarlu, Vunnam,Singh, Parvinder Pal,Vishwakarma, Ram A.
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p. 811 - 814
(2014/02/14)
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- Benzoquinone-promoted aerobic oxidative hydroxylation of arylboronic acids in water
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A general and efficient aerobic oxidative hydroxylation of arylboronic acids promoted by benzoquinone in water was realized, and provided phenols in 72-95% yields for 20 examples. The main advantages of this protocol are the use of water as solvent in the presence of a catalytic amount of benzoquinone, and metal-free conditions. Georg Thieme Verlag KG Stuttgart · New York.
- Cheng, Guolin,Zeng, Xiaobao,Cui, Xiuling
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p. 295 - 300
(2014/02/14)
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- Lability of the trifluoromethyl group of trifluoromethoxybenzenes under HF/Lewis acid conditions
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The trifluoromethyl functionality of trifluoromethoxybenzenes (trifluoromethyl phenyl ethers) becomes labile under HF/Lewis acid conditions. Substrates with an unsubstituted para-position shed their -CF3 groups while performing a Friedel-Crafts reaction upon another substrate molecule's trifluoromethoxy group to generate p-rosolic acids. Substrates that had blocking groups at the para-positions reacted ortho. The electron donating substituents methoxy and phenoxy interfered with the formation of rosolic acids.
- Belter, Randolph K.
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scheme or table
p. 1302 - 1307
(2011/02/22)
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- (2R)-2-Methylchromane-2-carboxylic acids: Discovery of selective PPARα agonists as hypolipidemic agents
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A SAR study was conducted on chromane-2-carboxylic acid toward selective PPARα agonisim. As a result, highly potent, and selective PPARα agonists were discovered. The optimized compound 43 exhibited robust lowering of total cholesterol levels in hamster and dog animal models.
- Koyama, Hiroo,Boueres, Julia K.,Miller, Daniel J.,Berger, Joel P.,MacNaul, Karen L.,Wang, Pei-Ran,Ippolito, Marc C.,Wright, Samuel D.,Agrawal, Arun K.,Moller, David E.,Sahoo, Soumya P.
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p. 3347 - 3351
(2007/10/03)
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- Antihypertensive benzopyran derivatives
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Disclosed herein are novel benzopyrans represented by formula (I) STR1 wherein R1 is trifluoromethoxy or β, β, β-trifluoroethoxy; R2 and R3 are independently selected from the group consisting of hydrogen, lower alkyl containing 1 to 5 carbon atoms, cyclo lower alkyl containing 5 to 8 carbon atoms, STR2 or R2 and R3 are joined to form (--CH2 --)n wherein n is 4 to 7; or R2 and R3 are joined together to form (--CH2 --)m CO-- wherein m is 3 to 6; or R2 and R3 are joined together to form STR3 wherein R4 is selected from the group consisting of hydrogen, alkoxy containing 1 to 5 carbon atoms, amino or mono- or disubstituted alkyl amino wherein said alkyl groups contain 1 to 5 carbon atoms and the pharmaceutically acceptable salts and solvates thereof, to a process for preparing them, to pharmaceutical compositions containing them, and to their use in the treatment of hypertension, asthma, irritable bladder syndrome, and irritable bowel syndrome.
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- Antihypertensive benzopyran derivatives
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Disclosed herein are novel benzopyrans having pharmacological activity, to a process for preparing them, to pharmaceutical compositions containing them, and to their use in the treatment of hypertension.
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- Novel antihypertensive benzopyran derivatives
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Disclosed herein are novel benzopyrans having pharmacological activity, to a process for preparing them, to pharmaceutical compositions containing them, and to their use in the treatment of hypertension.
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- Antimycotically active substituted 2-aminothiazoles
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A 2-aminothiazole of the formula STR1 in which R1 represents hydrogen or alkyl and R2 represents a radical of the formula STR2 where R3, R4, R5 and R6 independently of one another in each case represent hydrogen, halogen, nitro, alkyl, alkoxy, alkoxycarbonyl, dialkylamino, alkylthio, alkylsulphinyl, alkylsulphonyl, halogenoalkyl, halogenoalkoxy, halogenoalkylthio, halogenoalkylsulphinyl or halogenoalkylsulphonyl, X represents oxygen, sulphur, sulphinyl or sulphonyl and Ar represents an unsubstituted aryl or a substituted aryl radical, and their physiologically tolerable acid addition salts.
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- Process for preparing hydroxylated aromatic compounds
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A process for preparing hydroxylated aromatic compounds optionally bearing at least one trifluoromethyl, trifluoromethoxy or trifluoromethylthio group. A chloroformate or fluoroformate, optionally bearing at least one trihalomethyl-, trihalomethoxy- or trihalomethylthiophenyl group, is reacted with liquid hydrofluoric acid. The aromatic compounds obtained are useful as synthesis intermediates in the pharmaceutical or the plant-protection industry.
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- Modifications of primaquine as antimalarials. 3. 5-Phenoxy derivatives of primaquine
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Various 5-phenoxy derivatives of primaquine have been prepared that are somewhat more effective and considerably less toxic that the parent compound in blood and tissue schizonticidal screens. Addition of a methyl group to the pyridine ring of the 5-phenoxyprimaquines has produced a number of antimalarials with potent activity against both blood and tissue schizonts.
- Nodiff,Tanabe,Chen,Saggiomo
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p. 1097 - 1101
(2007/10/02)
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- Preparation of aryl trifluoromethyl ethers
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A one-step process for the synthesis of aryl trifluoromethyl ethers by reacting phenol or certain substituted phenols with a perhalomethane and hydrogen fluoride is provided. The compounds produced by the process of this invention are useful intermediates in the production of dyestuffs and pharmaceuticals.
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- Copper-catalyzed synthesis of phenol and diaryl ether derivatives: Via hydroxylation of diaryliodoniums
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A copper-catalysed hydroxylation of diaryliodoniums to generate phenols and diaryl ethers is reported. This method allows the synthesis of diversely functionalized phenols under mild reaction conditions without the need for a strong inorganic base or an expensive noble-metal catalyst. Significantly, convenient application of diaryliodoniums is demonstrated in the preparation of diaryl ethers in a one-pot operation.
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