- Method for preparing bromo reagent by oxidative bromination reaction and method for further preparing bromine-containing compound
-
The invention relates to a method, and for preparing a bromine-containing compound through a reaction, of a :electron-substituted furan compound.rich electron-substituted furan compound, rich in an electron-rich substituted thiophene compound: The substituent of,rich electron-substituted furan compound containing, of an electron-rich substituted furan compound . The method for preparing the bromine-containing compound by the reaction of the present invention comprises the following steps. preparing an electron-rich substituted furan), compound (by). reacting with a bromine, containing substituted phenyl group, (.rich, electron-substituted furan compound and an aromatic or unsaturated bond-containing compound with an electron-rich substituted furan compound containing an electron-rich substituted furan compound.
- -
-
Paragraph 0028-0029
(2020/03/17)
-
- New procedure for the highly regioselective aerobic bromination of aromatic compounds using copper-based nanocatalyst
-
A new procedure for the highly regioselective aerobic bromination of aromatic compounds in the presence of copper-based nanoparticles (CuO/ZnO nanocatalyst) under reflux condition is described. Mechanistic parameters are discussed and the plausible mechanism is proposed. Recyclability of the CuO/ZnO nanocatalyst has also been explored upon aerobic bromination of aromatic compounds.
- Albadi, Jalal,Jalali, Mehdi
-
p. 234 - 239
(2020/02/29)
-
- Mechanistic Analysis of Solid-State Colorimetric Switching: Monoalkoxynaphthalene-Naphthalimide Donor-Acceptor Dyads
-
There is growing interest in creating solids that are responsive to various stimuli. Herein we report the first molecular-level mechanistic picture of the thermochromic polymorphic transition in a series of MAN-NI dyad crystals that turn from orange to yellow upon heating with minimal changes to the microscopic morphology following the transition. Detailed structural analyses revealed that the dyads assemble to create an alternating bilayer type structure, with horizontal alternating alkyl and stacked aromatic layers in both the orange and yellow forms. The observed dynamic behavior in the solid state moves as a yellow wavefront through the orange crystal. The overall process is critically dependent on a complex interplay between the layered structure of the starting crystal, the thermodynamics of the two differently colored forms, and similar densities of the two polymorphs. Upon heating, the orange form alkyl chain layers become disordered, allowing for some lateral diffusion of dyads within their own layer. Moving to either adjacent stack in the same layer allows a dyad to exchange a head-to-head stacking geometry (orange) for a head-to-tail stacking geometry (yellow). This transition is unique in that it involves a nucleation and growth mechanism that converts to a faster cooperative wavefront mechanism during the transition. The fastest moving of the wavefronts have an approximately 38° angle with respect to the long axis of the crystal, corresponding to a nonconventional C-H···O hydrogen bond network of dyad molecules in adjacent stacks that enables a transition with cooperative character to proceed within layers of orange crystals. The orange-to-yellow transition is triggered at a temperature that is very close to the temperature at which the orange and yellow forms exchange as the more stable, while being lower than the melting temperature of the original orange, or final yellow, solids.
- Wight, Christopher D.,Xiao, Qifan,Wagner, Holden R.,Hernandez, Eduardo A.,Lynch, Vincent M.,Iverson, Brent L.
-
supporting information
p. 17630 - 17643
(2020/11/12)
-
- COMPOUNDS FOR THE INHIBITION OF UNREGULATED CELL GROWTH
-
The present invention discloses compounds for inhibition of uncontrolled cell proliferation particularly cancer stem cells. Particularly, the invention relates to compounds of Formula I to XXII for the treatment of cancer.
- -
-
Page/Page column 28-29; 40
(2020/07/14)
-
- PROTEIN KINASE C AGONISTS
-
The present disclosure relates generally to certain diacylglycerol lactone compounds, pharmaceutical compositions comprising said compounds, and methods of making and using said compounds and pharmaceutical compositions. The compounds and compositions disclosed herein may be used for the treatment or prevention of diseases, disorders, or infections modifiable by protein kinase C (PKC) agonists, such as HIV.
- -
-
Paragraph 0315
(2020/09/12)
-
- Mild and Regioselective Bromination of Phenols with TMSBr
-
In this work, an unexpected promoting effect of by-product thioether was observed, leading to a mild and regioselective bromination of phenols with TMSBr. This method can tolerate a series of functional groups such as the reactive methoxyl, amide, fluoro, chloro, bromo, aldehyde, ketone and ester groups, and has the potential to recycle the by-product thioether and isolate the desired product under column chromatography-free conditions. Mechanism studies revealed that O–H···S hydrogen bond may be formed between phenol and by-product thioether. Possibly owing to the steric hindrance effect from by-product thioether, the electrophilic bromination at para-position of phenols is much favorable.
- Ma, Xiantao,Yu, Jing,Jiang, Mengyuan,Wang, Mengyu,Tang, Lin,Wei, Mengmeng,Zhou, Qiuju
-
supporting information
p. 4593 - 4596
(2019/07/05)
-
- Regioselective bromination of arenes mediated by triphosgene-oxidized bromide
-
This article first time describes triphosgene (BTC) as an oxidant while the non-toxic and easy-to-handle potassium bromide (KBr) as the source of bromine to the bromination reaction of aromatic substrates. The novel brominating protocol gives excellent para-regioselectivity of the alkoxyl/hydroxyl arenes and high yield, offering good potential of commercial scale applications. The mechanism of “Triphosgene oxidize bromide” was proposed.
- Xu, Yingzhou,Hu, Dufen,Zheng, Hui,Mei, David,Gao, Zhaobo
-
supporting information
(2019/08/30)
-
- aromatic compound having fused cyclic substituent in aromatic ring and organic light-emitting diode including the same
-
The present invention relates to a compound having a cyclic substituent fused with a cyclic ring and an organic light emitting diode including the same, and more particularly, to a compound for an organic light emitting diode represented by chemical formula A and an organic light emitting diode including the same. In chemical formula A, X is a substituent having structural formula X, Y is a substituent of structural formula Y1, n is an integer from 1 to 4, and structural formulas X and Y1 are the same as described in detailed description of the present invention.
- -
-
Paragraph 0345-0347
(2019/01/06)
-
- ANTICANCER COMPOUNDS
-
The present invention discloses compounds for inhibition of uncontrolled cell proliferation particularly in cancer stem cells. Particularly, the invention relates to compounds of Formula III to XIV for the treatment of cancer, such as breast and prostate cancer.
- -
-
Page/Page column 36; 37
(2018/11/22)
-
- aromatic compound having fused cyclic substituent in aromatic ring and organic light-emitting diode including the same
-
The present invention refers to to the aromatic ring-fused ring withdrawing substituent and a compound having an same relates to organic light emitting device including, more specifically a represented by [formula A] an alkali-soluble polymer resin compound for an organic light-emitting device including organic light emitting device is characterized in that the. [Formula A] In said [formula A], X has a dementia drug; and shows strong X having substituted group, Y has a dementia drug; and shows strong formula selected from the group consisting Y1 to Y5 having one of substituted group, the n being integers, of 4 to 1, the Y5 formula to Y1 formula and X formula detailed description of the invention is described. (by machine translation)
- -
-
Paragraph 0357; 0358
(2016/10/10)
-
- Time-dependent solid-state polymorphism of a series of donor-acceptor dyads
-
In order to exploit the use of favorable electrostatic interactions between aromatic units in directing the assembly of donor-acceptor (D-A) dyads, the present work examines the ability of conjugated aromatic D-A dyads with symmetric side chains to exhibit solid-state polymorphism as a function of time during the solid formation process. Four such dyads were synthesized, and their packing in the solid state from either slower (10-20 days) or faster (1-2 days) evaporation from solvent was investigated using single crystal X-ray analysis and powder X-ray diffraction. Two of the dyads exhibited tail-to-tail (A-A) packing upon slower evaporation from solvent and head-to-tail (D-A) packing upon faster evaporation from solvent. A combination of single-crystal analysis and XRD patterns were used to create models, wherein a packing model for the other two dyads is proposed. Our findings suggest that while side chain interactions in asymmetric aromatic dyads can play an important role in enforcing segregated D-A dyad assembly, slowly evaporating symmetrically substituted aromatic dyads allows for favorable electrostatic interactions between the aromatic moieties to facilitate the organization of the dyads in the solid state.
- Peebles, Cameron,Alvey, Paul M.,Lynch, Vincent,Iverson, Brent L.
-
supporting information
p. 290 - 299
(2014/01/17)
-
- CHLORO-PYRAZINE CARBOXAMIDE DERIVATIVES WITH EPITHELIAL SODIUM CHANNEL BLOCKING ACTIVITY
-
This invention provides compounds of the formula I: and their pharmaceutically acceptable salts, useful as sodium channel blockers, compositions containing the same, therapeutic methods and uses for the same and processes for preparing the same.
- -
-
Paragraph 0416; 0417; 0434
(2014/06/25)
-
- Emission and transient absorption measurements of substitution effects of C-C triple bonds on relaxation processes of the fluorescent state of naphthalenes
-
Photophysical and photochemical properties of naphthalenes substituted with trimethylsilylethynyl, tert-butylethynyl, and trimethylsilylbutadiynyl groups were investigated by measurement of fluorescence yields, lifetimes, and triplet absorption. Introducing trimethylsilylethynyl and tert-butylethynyl groups to the 1-position of the naphthalene skeleton substantially enhanced fluorescence and intersystem crossing (ISC). The rates of fluorescence of 2-substituted naphthalenes were low. The effect of ethynyl groups on the 1-substituted naphthalenes was rationalized in terms of an increase of the transition moment along the short axis of the naphthalene skeleton. Substitution of the trimethylsilylbutadiynyl group at the 1 or 2-position of the naphthalene skeleton caused a considerable decrease in the fluorescence yield (approximately 0.01) and an increase in the ISC yield (0.99).
- Yamaji, Minoru,Maeda, Hajime,Minamida, Keita,Maeda, Tomohiro,Asai, Kengo,Konishi, Gen-Ichi,Mizuno, Kazuhiko
-
p. 321 - 345
(2013/03/14)
-
- CARBOXAMIDE OR SULFONAMIDE SUBSTITUTED THIAZOLES AND RELATED DERIVATIVES AS MODULATORS FOR THE ORPHAN NUCLEAR RECEPTOR ROR[GAMMA]
-
The invention provides modulators for the orphan nuclear receptor RORy and methods for treating RORy mediated diseases by administering these novel RORy modulators to a human or a mammal in need thereof. Specifically, the present invention provides carboxamide or sulfonamide containing cyclic compounds of Formula (1), (1'), (100), (100'), (200) and (200') and the enantiomers, diastereomers, tautomers, /V-oxides, solvates and pharmaceutically acceptable salts thereof.
- -
-
Page/Page column 104
(2014/01/07)
-
- Facile synthesis of lipophilic δ-amino acid conjugates from 4-alkoxy-dithionaphthoic acids
-
(Chemical Equation Presented) Novel 4-alkoxy-dithionaphthoic acids were prepared and shown to be valuable synthons for δ-amino acid conjugates. These dithioacids are efficiently synthesized and purified, stable to storage, and easily derivatized to facilitate thioacylation chemistry. To this end, we have demonstrated dithionaphthoic acids (6) to successfully undergo coupling with both protected and unprotected amino acids, giving rise to stable thioamide conjugates (8 and 9). Copyright Taylor & Francis Group, LLC.
- Worth, Anna C.,Needham, Catherine E.,Franklin, Donald B.,Lampkins, Andrew J.
-
scheme or table
p. 2694 - 2706
(2012/07/28)
-
- A succinct synthesis of the vaulted biaryl ligand vanol via a dienone-phenol rearrangement
-
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.
-
experimental part
p. 2130 - 2146
(2011/10/18)
-
- Simple and improved regioselective brominations of aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide under mild reactions conditions
-
A simple, efficient, and mild method for the selective bromination of some activated aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide in non-aqueous solution is reported. The results obtained revealed good to excellent selectivity between the ortho and para positions of phenols and methoxyarenes.
- Ghasemnejad-Bosra, Hassan,Ramzanian-Lehmali, Farhad,Jafari, Somaye
-
experimental part
p. 685 - 692
(2012/01/16)
-
- Chemo-and regioselective bromination of aromatic compounds in the presence of γ-picolinium bromochromate (γ-PBC)/CH3CN
-
Regioselective oxidative bromination of activated aromatic compounds has been studied using γ-Picolinium bromochromate in either CH3COOH or CH3CN is reported. The results obtained revealed excellent yields of monobromo compounds at para-position under thermal condition especially in methyl cyanide.
- Mahmoodi,Yazdanbakhsh,Hassanzadeh
-
experimental part
p. 429 - 434
(2012/04/04)
-
- Regiospecific oxyhalogenation of aromatics over SBA-15-supported nanoparticle group IV-VI metal oxides
-
TiOx, VOx, MoOx and WOx supported on SBA-15 exhibit efficient catalytic activity for oxyhalogenation of aromatics with the H2O2-halide ion system. Unlike the hitherto known solid catalysts, these reusable catalysts yield the para-halogenated product with 100% selectivity at 298 K and moderate acidic pH (3-5). The catalytic activity was enhanced by five orders of magnitude when supported on SBA-15. Springer Science+Business Media, LLC 2010.
- Saikia,Rajesh,Srinivas,Ratnasamy
-
scheme or table
p. 190 - 201
(2010/11/05)
-
- Enantioselective synthesis of (+)-estrone exploiting a hydrogen bond-promoted Diels?Alder reaction
-
Starting from Danes diene and methylcyclopentenedione, (+)-estrone is synthesized along the Quinkert?Dane route in 24% total yield. The key step is an enantioselective Diels?Alder reaction promoted by an amidinium catalyst as efficiently as by a traditional Ti-TADDOLate Lewis acid.
- Weimar, Marko,Duerner, Gerd,Bats, Jan W.,Goebel, Michael W.
-
supporting information; experimental part
p. 2718 - 2721
(2010/07/17)
-
- POLY AROMATIC SODIUM CHANNEL BLOCKERS
-
Polyaromatic sodium channel blockers represented by the formula: are provided where the structural variables are defined herein. The invention also includes a variety of compositions, combinations and methods of treatment using these inventive sodium channel blockers.
- -
-
-
- Regioselective, photochemical bromination of aromatic compounds using N-bromosuccinimide
-
Regioselective nuclear bromination of aromatic compounds is investigated with N-bromosuccinimide as the brominating agent under UV irradiation to afford the corresponding brominated compounds. The reaction proceeds at ambient temperature (30 ± 2 °C) without any catalyst. In most of the reactions, regioselectively mono-brominated products are obtained in good to high yields. The conversion and selectivity for bromination depend on the nature of the substituent on the aromatic ring.
- Chhattise, Prakash K.,Ramaswamy,Waghmode, Suresh B.
-
p. 189 - 194
(2008/03/30)
-
- Bromination of some aromatic compounds with potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate
-
A simple, efficient, and mild method for selective bromination of some activated aromatic compounds using potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate in nonaqueous solution is reported. The results obtained revealed good to excellent selectivity between ortho and para positions of phenols and methoxyarenes. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Mohammadpoor-Baltork, Iraj,Albadi, Jalal
-
p. 323 - 328
(2007/10/03)
-
- Synthesis of hydroxy, epoxy, nitrato and methoxy derivatives of tetralins and naphthalenes
-
Stereoselective syntheses are described for cis,trans,cis-2,3,5-tribromo-1, 4-dihydroxytetralin, trans,trans,cis-2,3,5-tribromo-1,4-dihydroxytetralin, trans,trans,trans-1,4-dihydroxy-2,3-dibromotetralin, trans,trans,trans-1- hydroxy-2,3,4-tribromotetralin, cis,cis,cis-1,2-epoxy-3,5-dibromo-4- hydroxytetralin, anti-1,2:3,4-diepoxytetralin, 1-hydroxy-4-bromonaphthalene, trans,trans,trans-1,4-dinitrato-2,3-dibromotetralin, 1-nitrato-2,3,4- tribromotetralin, 2,3-dibromonaphthalene and 1-methoxy-4-nitrato-2,3- dibromonaphthalene. These isomeric arene oxides and disubstituted naphthalenes provide excellent precursors for a number of 1,4- and 2,3-disubstituted naphthalene derivatives that are difficult to prepare using other routes. The structures of the naphthalene and tetralin derivatives were assigned by NMR and other techniques.
- Erenler, Ramazan,Demirtas, Ibrahim,Buyukkidan, Bulent,Cakmak, Osman
-
p. 753 - 757
(2007/10/03)
-
- Mild regioselective monobromination of activated aromatics and heteroaromatics with N-bromosuccinimide in tetrabutylammonium bromide
-
Highly regioselective nuclear bromination of activated aromatic and heteroaromatic compounds has been accomplished using N-bromosuccinimide in tetrabutylammonium bromide. Pre-dominant para-selective monobromination of activated aromatics such as phenols and anilines, rate acceleration of bromination for moderately activated and less reactive substrates on addition of acidic montmorillonite K-10 clay, with or without microwave assistance, are the notable features of this protocol.
- Ganguly, Nemai C.,De, Prithwiraj,Dutta, Sanjoy
-
p. 1103 - 1108
(2007/10/03)
-
- SUBSTITUTED PIPERAZINES, (1,4) DIASZEPINES, AND 2,5-DIAZABICYCLO (2.2.1) HEPTANES AS HISTAMINE H1 AND/OR H3 ANTAGONISTS OR HISTAMINE H3 REVERSE ANTAGONISTS
-
The present invention relates to novel piperazine and azepine derivatives having pharmacological activity, processes for their preparation, to compositions containing them and to their use in the treatment of neurodegenerative disorders including Alzheimer's disease.
- -
-
-
- Structure-Activity Relationships of Potent, Selective Inhibitors of Neuronal Nitric Oxide Synthase Based on the 6-Phenyl-2-aminopyridine Structure
-
The synthesis and structure-activity relationships of a series of 6-phenyl-2-aminopyridines that potently and selectively inhibit the neuronal isoform of nitric oxide synthase (nNOS) are described. Compound 14bi from this series exhibits potent in vivo activity in harmaline-induced cGMP formation in rat cerebellum, a functional model of nNOS inhibition, and in the PCP-induced hypermotility model in the rat. These results suggest that 14bi may be a useful reagent for evaluating potential therapeutic applications of nNOS inhibitors in the central nervous system.
- Lowe III, John A.,Qian, Weimin,Drozda, Susan E.,Volkmann, Robert A.,Nason, Deane,Nelson, Robert B.,Nolan, Charles,Liston, Dane,Ward, Karen,Faraci, Steve,Verdries, Kim,Seymour, Pat,Majchrzak, Michael,Villalobos, Anabella,White, W. Frost
-
p. 1575 - 1586
(2007/10/03)
-
- Protease inhibitors
-
The present invention provides compounds of formula (I) which inhibit proteases, including cathepsin K, pharmaceutical compositions of such compounds, and methods for treating diseases of excessive bone loss or cartilage or matrix degradation, including osteoporosis; gingival disease including gingivitis and periodontitis; arthritis, more specifically, osteoarthritis and rheumatoid arthritis; Paget's disease; hypercalcemia or malignancy; and metabolic bone disease therewith.
- -
-
-
- Investigations into the bromination of substituted phenols using diethyl bromomalonate and diethyl dibromomalonate
-
Substituted 4-bromophenols can be synthesised efficiently by heating the corresponding phenol in either neat diethyl bromomalonate or diethyl dibromomalonate. We discuss the regioselectivity of such reactions and comment on the scope and limitation of this procedure.
- Coumbarides,Dingjan,Eames,Weerasooriya
-
p. 179 - 180
(2007/10/03)
-
- Directed Reactions of C-Sulfenyl Halides with 1-Hydroxynaphthalene Derivatives
-
C-Sulfenyl chlorides react with 1-hydroxynaphthalene derivatives in nitrobenzene with the formation of sulfenylation products sulfenylation. Under the same conditions C-sulfenyl bromides furnish the products of bromination. In the presence of potassium perchlorate the reactions occurs place also in dioxane and acetonitrile with retention of different in reactivity patterns of isostructural chlorides and bromides. In the reaction with 1-hydroxynaphthalene 2-nitro- and 2,4-dinitrobenzenesulfenylbromides both afford the bromination and sulfenylation products in unsimilar ratios.
- Movchan,Ziganshina,Akhmetov,Dykhal,Chmutova
-
p. 502 - 509
(2007/10/03)
-
- Regioselective catalytic halogenation of aromatic substrates
-
Regioselective chlorination and bromination of some aromatic substances have been carried out using KCl and KBr in presence of sodium perborate as an oxidant and sodium metavanadate, sodium tungstate, ammonium metavanadate and ammonium molybdate as efficient catalysts. This environmentally friendly catalytic halogenation method gave good yields of products under mild conditions.
- Bandgar,Nigal, Neeta J.
-
p. 3225 - 3229
(2007/10/03)
-
- N-Bromosuccinimide as a Regioselective Nuclear Monobrominating Reagent for Phenols and Naphthols
-
A wide range of substituted phenols and naphthols were regioselectively monobrominated with N-bromosuccinimide, at para position in acetonitrile and at ortho position in carbon disulfide, under mild conditions in good yields. Methylphenols afforded only nuclear bromination products.
- Carre?o, M. Carmen,García Ruano, José L.,Sanz, Gema,Toledo, Miguel A.,Urbano, Antonio
-
p. 1241 - 1242
(2007/10/03)
-
- Kinetics and mechanism of ammonolysis and alkaline hydrolysis of naphthyl acetates in aqueous medium: Part 1 - 4-Substituted 1-naphthyl acetates
-
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
-
p. 749 - 753
(2007/10/03)
-
- Regioselective Catalytic Halogenation of Arenes, mimicking Vanadium Haloperoxidase Reactions
-
Ammonium metavanadate, mimicking vanadate dependent metalloenzymes, efficiently catalyses the halogenation of arenes in moderate to good yields using dilute hydrogen peroxide (30%) as an oxidizing agent, exhibiting remarkable regioselectivity.
- Hegde, Vishnumurthy R.,Pais, Godwin C. G.,Kumar, Rajiv,Kumar, Pradeep,Pandey, Bipin
-
-
- Syntheses of Calixnaphthalenes Derived from 1-Naphthol
-
Using a convergent synthetic strategy, the synthesis of the previously elusive C4ν-symmetrical calixnaphthalene from 1-naphthol is described.Using other independent convergent routes, syntheses of the other three isomeric calixnaphthalenes originally formed from the direct base-catalyzed condensation of formaldehyde with 1-naphthol are also described.All of these methods involved either a TiCl4- or TFA-assisted coupling reaction to achieve the cyclization steps.A mechanism is proposed to account for the formation of the original three isomeric calixnaphthalenes from the base-catalyzed condensation of formaldehyde with 1-naphthol.
- Georghiou, Paris E.,Ashram, Muhammad,Li, Zhaopeng,Chaulk, Steven G.
-
p. 7284 - 7289
(2007/10/03)
-
- Bromation regioselective en serie aromatique. I: Monobromation en position para de phenols et d'amines aromatiques par le tribromure de tetrabutylammonium
-
The reaction of tetrabutylammonium tribromide (TBABr3) with phenols and aromatic amines in aprotic and non-basic solvents at 20 deg C gives exclusively the corresponding para-brominated compounds in high yields.A mechanism involving electrophilic substitution by the tribromide anion Br3- itself is suggested to account for the results, especially the regioselective para bromination.Key words: bromination, tetrabutylammonium tribromide, phenols, aromatic amines.
- Berthelot, Jacques,Guette, Catherine,Desbene, Paul-Louis,Basselier, Jean-Jacques,Chaquin, Patrick,Masure, Daniel
-
p. 2061 - 2066
(2007/10/02)
-
- THE INTERMEDIATES IN THE INTERACTION OF PHENOLS WITH N-BROMOSUCCINIMIDE
-
Phenols react with N-bromosuccinimide to generate 2-bromocyclohexadienone-type intermediates that enolize to 2-bromophenols thermally or photolytically with a wide range of rate constants depending on the parent phenol.A trace amount of acids not only accelerates the rates of the formation and decomposition of the 2-bromodienones, it also promotes the rearrangement of the 2-bromodienones to cross-conjugated 4-bromocyclohexadienones.The enolization of these last compounds affords 4-bromophenols.The occurrence of autocatalysis in dienone decompositions arising from more acidic bromophenols is also established.The reaction is assumed to occur by a bromophilic attack of phenols on the N-Br bond to form unstable hypobromites that rapidly rearrange to the 2-bromocyclohexadienone intermediates.The quantum yield of the photodecomposition of 2-bromo-(2H)-naphthalene-1-one in the vicinity of 365 nm was determined to be unity.
- Chow, Yuan L.,Zhao, Da-Chuan,Johansson, Carl J.
-
p. 2556 - 2564
(2007/10/02)
-
- Oxybromination Catalysed by the Heteropolyanion Compound H5PMo10V2O40 in an Organic Medium: Selective para-Bromination of Phenol
-
Selective bromination of phenol and its derivatives and the bromination of ketones and alkenes have been achieved by oxybromination at ambient conditions catalysed by the mixed addenda heteropolyanion compound H5PMo10V2O40, which is dissolved in a nonpolar chlorohydrocarbon solvent by complexation with tetraglyme.
- Neumann, Ronny,Assael, Igal
-
p. 1285 - 1287
(2007/10/02)
-
- BROMINATION OF KETONES AND PHENOLS WITH 4-(TRIBROMOMETHYL)QUINAZOLINE
-
4-(Tribromomethyl)quinazoline, 1, in benzene behaves as a brominating agent towards ketones (in the enol form) and phenols.The reaction has the features of a polar reaction, notwithstanding the nature of the solvent.Ketones and phenols behave as nucleophiles, and attack a bromine atom of the brominating agent.
- Mencarelli, Paolo,Stegel, Franco
-
-
- Enolization of the benzocyclohexadienone formed during the bromination of 1-naphthol in aqueous solution
-
Benzo-4-bromo-2,5-cyclohexadienone (5) has been observed in the aqueous bromination of 1-naphthol and the kinetics of its enolization to 4-bromo-1-naphthol have been studied in the pH range 0-7.This process is catalyzed by the proton, hydroxide ion, water, buffer acids, and by buffer bases.For ctalysis by general bases the Broensted β = 0.59 whereas catalysis by general acids has a value of α ca. 0.These findings are very similar to those obtained previously for the 4-bromo-2,5-cyclohexadienone 2b, formed during the aqueous bromination of 2,6-dimethylphenol.The mechanistic implications of the results are discussed.The enolization of the related dienone 8, formed from bromine and 1-naphthol-2-carboxylic acid, was also studied.At acidic pHs the dienone 8 is much more reactive than 5, with the 2-COOH behaving as an internal catalyst having an "effective molarity" of about 110 M.The enolization of 8 is also catalyzed by buffer bases.
- Tee, Oswald S.,Iyengar, N. Rani
-
p. 1714 - 1718
(2007/10/02)
-
- Halogenation Using Quaternary Ammonium Polyhalides. IV. Selective Bromination of Phenols by Use of Tetraalkylammonium Tribromides
-
Reaction of phenols with calculated amounts of benzyltrimethylammonium tribromide or tetrabutylammonium tribromide in dichloromethane-methanol for 0.5-1 h under mild conditions gave, selectively, the objective mono-, di-, or tribromophenols in good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Okamoto, Tsuyoshi,Nakamura, Hiroko,Fujikawa, Masahiro
-
p. 4187 - 4189
(2007/10/02)
-
