- Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
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An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
- Xiong, Xiaodong,Yeung, Ying-Yeung
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p. 4033 - 4043
(2018/05/22)
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- In Situ Formed IIII-Based Reagent for the Electrophilic ortho-Chlorination of Phenols and Phenol Ethers: The Use of PIFA-AlCl3 System
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A new and in situ formed reagent generated by mixing PIFA {bis[(trifluoroacetoxy)iodobenzene]} and AlCl3 was introduced in the organic synthesis for the direct and highly regioselective ortho-chlorination of phenols and phenol ethers. An efficient electrophilic chlorination for these electron-rich arenes as well as the scope of the reaction are described herein. An easy, practical, and open-flask reaction allowed us to introduce a chlorine atom, which is a highly important functional group in organic synthesis. The reproducibility of our method has been demonstrated on gram-scale by carrying out the reaction in 6-bromo-2-naphthol. This halogenation reaction also proceeds in excellent conditions by first preparing the iodine(III)-based chlorinating reagent. Our new chlorinating reagent can be stored at least for two weeks at 4 °C without losing its reactivity.
- Nahide, Pradip D.,Ramadoss, Velayudham,Juárez-Ornelas, Kevin A.,Satkar, Yuvraj,Ortiz-Alvarado, Rafel,Cervera-Villanueva, Juan M. J.,Alonso-Castro, ángel J.,Zapata-Morales, Juan R.,Ramírez-Morales, Marco A.,Ruiz-Padilla, Alan J.,Deveze-álvarez, Martha A.,Solorio-Alvarado, César R.
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p. 485 - 493
(2018/02/09)
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- Regioselective C-H chlorination: Towards the sequential difunctionalization of phenol derivatives and late-stage chlorination of bioactive compounds
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We have developed a protocol for the auxillary directed C-H chlorination of phenol derivatives using catalytic amounts of palladium acetate that is amenable to the late-stage chlorination of diflufenican and estrone. The 2-pyridine group allows for a highly efficient palladium-catalyzed chlorination and sequential ortho C-H functionalization reaction of phenol derivatives to produce a variety of symmetrical and unsymmetrical 2,4,6-trisubstituted phenols.
- Gao, Chao,Li, Hongchen,Liu, Miaochang,Ding, Jinchang,Huang, Xiaobo,Wu, Huayue,Gao, Wenxia,Wu, Ge
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p. 46636 - 46643
(2017/10/16)
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- Multisubstituted benzo[b]furans through a copper- and/or palladium-catalyzed assembly and functionalization process
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Full details as well as the study of the scope, limitations, and further elaboration of a straightforward approach to the synthesis of 2,5,7-trisubstituted benzo[b]furans from 2-bromo- and 2-chloro-6-iodo-4- substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki-Miyaura cross-coupling, alkynylation, alkenylation, and C-N bond forming reactions. A one-pot protocol for the synthesis of 2,5,7-trisubstituted benzo[b]furans is also reported.
- Arcadi, Antonio,Blesi, Federico,Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella,Marinelli, Fabio
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p. 1857 - 1871
(2013/04/10)
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- 2,5,7-Trisubstituted benzo[b]furans through a copper- and/or palladium-catalyzed assembly and functionalization process
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A straightforward approach to the synthesis of 2,5,7-trisubstituted benzo[b]furans from 2-bromo- and 2-chloro-6-iodo-4-substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki-Miyaura cross-coupling and C-N bond forming reactions.
- Arcadi, Antonio,Blesi, Federico,Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella
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scheme or table
p. 5149 - 5152
(2011/10/12)
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- Syntheses and herbicidal activity of pyrazolyl benzoxazole derivatives
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(Chemical Equation Presented) In recent years, protoporphyrinogen oxidase (Protox) inhibitor herbicides are developed rapidly, because of this type of herbicides shows high herbicidal activity and low toxicity. In this paper, we prepared a series of new substituted pyrazolyl benzoxazole derivative, which were synthesized from 4-fluorophenol, via a serial of reactions included chlorination, acylation, condensation, ring closure, methylation, nitration, and so on. All the structures are confirmed by 1H NMR, MS and element analysis. Preliminary bioassay shows that most substituted pyrazolyl benzoxazole derivatives exhibit high herbicidal activity to the tested gramineous weeds and latifoliate weeds.
- Xue, Na,Zhou, Yuhan,Wang, Guowei,Miao, Weirong,Qu, Jingping
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scheme or table
p. 15 - 21
(2010/05/03)
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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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- Kinetics of chlorination of phenol and monosubstituted phenols by t-butyl hypochlorite in aqueous alkaline medium
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The kinetics of chlorination of the parent and sixteen monosubstituted phenols (2-chloro, 2-methyl, 2-carboxy, 2-nitro, 3-chloro, 3-methyl, 3-carboxy, 4-fluoro, 4-chloro, 4-bromo, 4-methyl, 4-ethyl, 4-methoxy, 4-carboxy, 4-acetyl and 4-nitro) by t-BuOCl have been studied in aqueous alkaline medium. The rates of reactions show first order kinetics each in |t-BuOCl| and |XC 6H4OH| and inverse first order in |OH-|. Variation in either ionic strength or addition of reaction product has no significant effect on the rates of reactions, while lowering of the dielectric constant of the medium increases the rate. The rates are measured at different temperatures and the activation parameters for all the phenols computed. A mechanism involving the electrophilic attack of phenoxide ions by HOCl in the rate determining step is suggested. The rates decrease in the order: 3-CH 3 > 2-CH3 > 4-OCH3 > 4-CH3 > 4-C2H5 > H > 3-Cl > 3-COO- > 4-F > 2-COO- > 4-Br > 2-Cl > 4-Cl > 4-COO- > 4-COCH3 > 2-NO2 > 4-NO2. Hammett equation of the type, log k = -3.44 - 2.35 ρ is found to be valid for substituent effects. The enthalpy and entropy of activation are correlated.
- Moodithaya,Gowda, B. Thimme
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p. 420 - 425
(2007/10/03)
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