- Catalyst-Controlled Regioselective Chlorination of Phenols and Anilines through a Lewis Basic Selenoether Catalyst
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We report a highly efficient ortho-selective electrophilic chlorination of phenols utilizing a Lewis basic selenoether catalyst. The selenoether catalyst resulted in comparable selectivities to our previously reported bis-thiourea ortho-selective catalyst, with a catalyst loading as low as 1%. The new catalytic system also allowed us to extend this chemistry to obtain excellent ortho-selectivities for unprotected anilines. The selectivities of this reaction are up to >20:1 ortho/para, while the innate selectivities for phenols and anilines are approximately 1:4 ortho/para. A series of preliminary studies revealed that the substrates require a hydrogen-bonding moiety for selectivity.
- Dinh, Andrew N.,Maddox, Sean M.,Vaidya, Sagar D.,Saputra, Mirza A.,Nalbandian, Christopher J.,Gustafson, Jeffrey L.
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p. 13895 - 13905
(2020/11/03)
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- Regioselective Oxidative Chlorination of Arenols Using NaCl and Oxone
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We developed a practical and environmentally benign method for the chlorinative dearomatization of arenols using transient electrophilic chlorinating species generated in situ from inexpensive sodium chloride and Oxone as a Cl source and oxidant, respectively, under mild conditions. Moreover, the regioselective chlorination or chlorinative dearomatization of 1-naphthols was also achieved by changing the reaction conditions.
- Uyanik, Muhammet,Sahara, Naoto,Ishihara, Kazuaki
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supporting information
p. 27 - 31
(2018/10/25)
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- 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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- Role of substituents on the reactivity and product selectivity in reactions of naphthalene derivatives catalyzed by the orphan thermostable cytochrome P450, CYP175A1
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The thermostable nature of CYP175A1 enzyme is of potential interest for the biocatalysis at ambient temperature or at elevated temperature under environmentally benign conditions. Although little is known about the substrate selectivity of this enzyme, the biocatalytic activities of CYP175A1 on different substituted naphthalenes have been studied in oxidative pathway, and the effect of the substituent on the reaction has been determined. The enzyme first acts as a peroxygenase to convert these substituted naphthalenes to the corresponding naphthols, which subsequently undergo in-situ oxidative dimerization to form dyes of different colors possibly by the peroxidase-type activity of CYP175A1. The product analyses and kinetic measurements suggested that the presence of electron releasing substituent (ERS) in the substrate enhanced the substrate conversion, whereas the presence of electron withdrawing substituent (EWS) in the substrate drastically reduced the substrate conversion. The position of the ERS in the substrate was also found to play an important role in the transformation of the substrate. The results further demonstrate that mutation of the Leu80 residue to Phe enhances the reactivity of the enzyme by favoring the substrate association in the active site. The observed rates of the enzymatic oxygenation reaction of the substituted naphthalenes followed the Hammett correlation of substituent effect, supporting aromatic electrophilic substitution mechanism catalyzed by the cytochrome P450 enzyme.
- Banerjee, Shibdas,Goyal, Sandeep,Mazumdar, Shyamalava
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- A succinct synthesis of the vaulted biaryl ligand vanol via a dienone-phenol rearrangement
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Vanol is a member of the vaulted biaryl family of ligands and it has been proven to be very effective in a number of asymmetric catalytic reactions. The previous synthesis of vanol, while effective, is limited by the cost of reagents involved. The present work evaluates three different approaches to the synthesis of 3-phenyl-1-naphthol, a key intermediate in the synthesis of vanol. The first approach has its key step as the Michael addition of a benzyl Grignard to methyl cinnamate. In the second approach the key step is the first step, a Reformatsky reaction of ethyl bromoacetate and deoxybenzoin. The final and most-efficient approach involves a dienone-phenol rearrangement of a 4-aryl-1-tetralenone generated in-situ from the reaction of 4-chloro-1-naphthol with AlCl3 and benzene, and preliminary results are reported on the extension of this method to substituted vanol derivatives.
- Ding, Zhensheng,Xue, Song,Wulff, William D.
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scheme or table
p. 2130 - 2146
(2011/10/18)
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- LEWIS ACID CATALYZED HALOGENATION OF ACTIVATED CARBON ATOMS
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A practical and efficient method for halogenation of activated carbon atoms using readily available /V-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.
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Page/Page column 26
(2008/06/13)
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- "On water": Unique reactivity of organic compounds in aqueous suspension
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(Chemical Equation Presented) Water, the medium of choice: Many reactions, such as Claisen rearrangements (see scheme), are dramatically accelerated when performed in aqueous suspension ("on water") relative to organic (Table Presented) solvents or even neat conditions. Low miscibility of organic compounds with water is not detrimental: in fact, it facilitates the isolation of products.
- Narayan, Sridhar,Muldoon, John,Finn,Fokin, Valery V.,Kolb, Hartmuth C.,Sharpless, K. Barry
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p. 3275 - 3279
(2007/10/03)
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- One step hair coloring compositions using salts
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A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
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- Process for the two-stage oxidation dyeing of keratin fibers with a manganese complex or salt and a 4-substituted 1-naphthol, and dyeing kit
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A process for the two-stage oxidation dyeing of keratin fibers by applying to the keratin fibers: in a first stage, at least one composition A containing at least one manganese salt and/or a manganese complex, in a second stage, at least one composition B having a pH of greater than or equal to 6, and resulting from the extemporaneous mixing of at least one composition B1 containing at least one 4-substituted 1-naphthol and at least one composition B2 containing at least one oxidizing agent, and corresponding multi-compartment dyeing kit.
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- Kinetics and mechanism of ammonolysis and alkaline hydrolysis of naphthyl acetates in aqueous medium: Part 1 - 4-Substituted 1-naphthyl acetates
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A series of 4- substituted 1-naphthyl acetates have been prepared. The kinetics of their ammonolysis have been followed at 20°, 25° and 30°C under pseudo-first order conditions at different pH in water containing 1% dioxan at an ionic strength of 1.0 mol dm-3. The possible mechanisms suggest the existence of general base catalysis for 4-methyl-1-naphthyl acetate. For esters with electron-withdrawing substituents, ammonolysis proceeds through an unassisted simple nucleophilic substitution pathway. The alkaline hydrolysis of all the esters is also followed under identical reaction conditions.
- Ananthakrishna Nadar,Rajarathinam
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p. 749 - 753
(2007/10/03)
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- Chromogenic substrate to peroxidase enzymes
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A novel chromogenic substrate to peroxidase enzymes is provided which is comprised of a mixture of an adduct formed from a hydrozone and a dienophile, and an aromatic nucleophile. The mixture undergos an oxidative coupling in the presence of peroxidase enzymes and peroxides forming a purple indamine dye. The mixture is also stable and unaffected by oxygen of the air or by hydrogen peroxide.
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- Carbonyl Oxide Chemistry. The NIH Shift
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Benzophenone oxide has been shown to oxidize 1-chloronaphthalene and p-xylene with accompanying NIH shift of chlorine and methyl, respectively.Similar oxidation of toluene leads to a mixture of o-,p-, and m-cresols while N-acetyl-L-phenylalanine ethyl ester is oxidized to the corresponding tyrosine derivative.The results are discussed in terms of their relationship to the "activation" of polycyclic aromatic hydrocarbons in polluted atmospheres and the possible production of mutagens/carcinogens.
- Kumar, S.,Murray, R. W.
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p. 1040 - 1045
(2007/10/02)
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- HALOGENATION REGIOSELECTIVE EN SERIE AROMATIQUE-II CHLORATION DES NAPHTOLS ET LEURS ETHERS A L'AIDE DE REACTIFS METTANT EN JEU DES INTERACTIONS DU TYPE DONNEUR-ACCEPTEUR
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The regispecific chlorination of naphtols by hexachlorocyclohexadienones as selective chlorinating reagents is described.The selectivity attained is better than that which we have obtained with phenol derivatives and confirms the importance of the donor-acceptor interaction between the reagent and the naphthol during the chlorination.
- Guy, Alain,Lemaire, Marc,Guette, Jean-Paul
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p. 2347 - 2354
(2007/10/02)
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- CONDENSATION OF PHENOLS AND THEIR DERIVATIVES WITH AROMATIC COMPOUNDS IN THE PRESENCE OF ACIDIC AGENTS. V. REACTIONS OF CHLORINE-SUBSTITUTED NAPHTHOLS WITH BENZENE
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Substitution of the chlorine at position 1 by a phenyl residue occurs readily in the reaction of 1-chloro- and 1,4-dichloro-2-naphthols with benzene in the presence of aluminum chloride and hydrogen chloride. 4-Chloro-2-naphthol reacts with considerably great difficulty, giving a small yield of 4-phenyl-2-naphthol.The possibility of using a mixture of 4- and 2-chloro-1-naphthols for the production of 3-phenyl-1-naphthol was demonstrated.The possible reaction paths are discussed.
- Repinskaya, I. B.,Savel'ev, V. A.,Makarova, Z. S.,Koptyug, V. A.
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p. 1463 - 1466
(2007/10/02)
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- Antimicrobial polycyclic nitrofurans
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2-Nitrobenzofurans in which the furan ring is either fused to or substituted by a fused bicyclic system, which are active as antimicrobial agents, processes for their use and intermediates therefor are described.
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