- PROTIODESILYLATION OF SUBSTITUTED 2-TRIMETHYLSILYLTHIOPHENS
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First-order rate constats at 50 deg C have been determined for cleavage of the thiophen compounds XC4H2SSiMe3-2 in mixtures of (a) MeOH (5 vol.) with aqueous HClO4 (2 vol.) and (b) CH3CO2H (4 vol.) with aqueous H2SO4 (3 vol.) Relative rates krel, in the first medium are (X =) 5-OMe, 7 200; 5-Me, 36; H, 1.00; 5-Cl, 1.08E-1; 5-Br, 9.0E-2; 3-Br, 5.0E-2; 4-Br, 4.9E-3, and in the second medium 5-Me, 36; H, 1.00; 5-Cl, 1.28E-1; 5-Br, 9.8E-2; 3-Br, 5.5E-2; 4-Br, 6.5E-3; 5-NO2, 9.1E-7; 3-NO2, 7.1E-7.Except for the nitro-compounds, the two sets of log krel values show excellent linear correlations with values for the corresponding XC6H4SiMe3 compounds, with 3-, 4-, and 5-X in the thiophen ring being taken as equivalent to o-, m-, and p-X groups, respectively, in the benzene ring, the effects of substituents being a litle larger in the thiophen than the benzene system; 3- and 5-O2NC4H2SSiMe3 are less reactive than would be expected from the correlations.Again with the exception of the data for the nitro-compound, the krel values for the 4- and 5- substituted thiophens show very good correlation with ?m+ and ?p+ constants.
- Seconi, Giancarlo,Eaborn, Colin
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- Cu3(BTC)2 as heterogeneous catalyst for the room temperature oxidative hydroxylation of arylboronic acids
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A well known copper based-metal organic framework (MOF), namely Cu3(BTC)2, is a suitable heterogeneous catalyst to promote the oxidative room-temperature hydroxylation of arylboronic acids to the corresponding phenols by H2O2. Using 0.5 equiv of H2O2, Cu3(BTC)2 exhibits 80% conversion in 60 min that is higher than 70% conversion achieved with Fe(BTC) under the same conditions and reaction time. Cu3(BTC)2 is reusable with no significant drop in the activity. Furthermore, powder XRD of the reused Cu3(BTC)2 shows no changes in crystallinity compared to the fresh Cu3(BTC)2, indicating catalyst stability is maintained under reaction conditions. The scope of Cu3(BTC)2 as heterogeneous catalyst for the oxidative hydroxylation was studied for various phenylboronic acids.
- Dhakshinamoorthy, Amarajothi,Asiri, Abdullah M.,Garcia, Hermenegildo
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- Convenient High-Yield Procedures for 2-Bromothiophene and 2,5-Dibromothiophene
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2-Bromothiophene is obtained in high yields by adding a solution of bromine in 48percent hydrobromic acid or a 35percent aqueous solution of hydrogen peroxide to a mixture of thiophene, diethyl ether, and 48percent hydrobromic acid. 2,5-Dibromothiophene is obtained in >90percent yields from thiophene and bromine in hydrobromic acid.
- Keegstra, M. A.,Brandsma, L.
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- CATALYTIC REDUCTIVE DEHALOGENATION OF THIOPHENE DERIVATIVES
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A method for the preparation of 3-substituted derivatives of thiophene by reductive dehalogenation of 2,5-dihalo-substituted thiophenes in the presence of a palladium complex is proposed.The dehalogenation reaction is a stepwise process.The presence of an acyl group in the 3 position increases the rate of the process.
- Sharf, V. Z.,Taits, S. Z.,Gurovets, A. S.,Vol'kenshtein, Yu. B.,Fabrichnyi, B. P.,Shcherbakova, S. I.
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- Pyridinium dichlorobromate: A new stable brominating agent for aromatic compounds
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Pyridinium dichlorobromate (PyHBrCl2, 1) is a new example of iminium-trihalide complexes. The compound is prepared from pyridine and chlorine in the presence of aqueous hydrogen bromide. The crystalline trihalide is quite stable and acts as a safe source of positive bromine. It shows a remarkable reactivity towards aromatic compounds compared with other bromine complexes. It is also considered as a potential source for bromine chloride BrCl.
- Muathen, Hussni A.
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- Halogenations of Aromatic Compounds with Halide Anions in the Presence of Nitrobenzenesulfonyl Peroxides. A Novel Method for the Formation of Positive Halogens
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A novel type of positive halogens, sulfonyl hypochlorite or sulfonyl hypobromite was formed in the reactions of halide anions with nitrobenzenesulfonyl peroxides; these hypohalites could be used as effective reagents for halogenation of aromatic rings.
- Yoshida, Masato,Mochizuki, Hideki,Kamigata, Nobumasa
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- Electrochemical reduction of mono- and dihalothiophenes at carbon cathodes in dimethylformamide. First example of an electrolytically induced halogen dance
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Cyclic voltammetry and controlled-potential electrolysis have been employed to probe the electrochemical reduction of a number of mono- and dihalothiophenes at carbon cathodes in dimethylformamide containing tetramethylammonium perchlorate. Reduction of 2
- Mubarak, Mohammad S.,Peters, Dennis G.
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- Green halogenation of aromatic heterocycles using ammonium halide and hydrogen peroxide in acetic acid solvent
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The green generation of X+ (X = Br, I) using hydrogen peroxide in aqueous acetic acid allows access to aromatic heterocyclic halides in yields and purities comparable to syntheses employing N-bromosuccinimide. In activated and unsubstituted thiophene rings, regioselectivity is quantitative for positions α to the sulfur; pyrroles also give quantitative reactions, at least initially. Deactivated rings, including furans and thiazoles, as well as thiophenes with strongly electron-withdrawing groups showed little to no reactivity under the conditions investigated. The reaction shows remarkable functional group tolerance (to alcohol, nitro, alkyl, halo, and carbonyl groups), as shown through reaction with substituted phenols. In all bromination reactions, reaction yields and regiochemistry were very similar to reactions involving N-bromosuccinimide in tetrahydrofuran solvent.
- D'Aleo, Danielle N.,Allard, Sheena R.,Foglia, Cassandra C.,Parent, Shawna L.M.,Rohr, David J.,Gottardo, Christine,MacKinnon, Craig D.
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- Photocatalytic Selective Bromination of Electron-Rich Aromatic Compounds Using Microporous Organic Polymers with Visible Light
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Pure organic, heterogeneous, metal-free, and visible light-active photocatalysts offer a more sustainable and environmentally friendly alternative to traditional metal-based catalysts. Here we report a series of microporous organic polymers containing photoactive conjugated organic semiconductor units as heterogeneous photocatalysts for a visible-light-promoted, highly selective bromination reaction of electron-rich aromatic compounds using HBr as a bromine source and molecular oxygen as a clean oxidant. Via a simple Friedel-Crafts alkylation reaction, the microporous organic polymers were obtained by cross-linking of organic semiconductor compounds with defined valence and conduction band positions. The utilization of the simply prepared porous polymer-based photocatalytic systems opens new opportunities toward a sustainable and efficient material design for catalysis.
- Li, Run,Wang, Zi Jun,Wang, Lei,Ma, Beatriz Chiyin,Ghasimi, Saman,Lu, Hao,Landfester, Katharina,Zhang, Kai. A. I.
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- Biphasic Electrophilic Halogenation of Activated Aromatics and Heteroaromatics with N-Halosuccinimides Catalyzed by Perchloric Acid
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Catalytic amounts of 70percent perchloric acid (0.1 - 10, mostly 0.1 - 1, mol percent, based on substrate) initiate the regioselective halogenation of activated aromatics and heteroaromatics with N-halosuccinimide (NXS, X = Cl or Br) in two-phase solid-liquid systems (NXS/hexane or NXS/CCl4) at room temperature to give ring-halogenated products in high yields.For example, thiophene is transformed to 2-halo or 2,5-dihalo derivatives (yield 82-98percent) using 1 or 2 equiv of NXS, respectively.Unsymmetrical 2,5-dihalothiophenes are obtained in 70-82percent yield by reacting 2-halothiophenes with an appropriate NXS.The reaction of 3-bromothiophene with NBS affords 2,3-dibromothiophene in 93-99percent yield. 1,3-Dimethoxybenzene and 2,3-dimethylanisole are halogenated regiospecifically at the 4-position to give the corresponding products in 81-94percent yield.
- Goldberg, Yuri,Alper, Howard
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- Influence of solvent polarity and viscosity on nonradiative processes in oligothiophenes with intramolecular charge transfer
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By the methods of luminescence, picosecond spectroscopy, and quantum-chemical calculations the mechanisms of electron excitation energy deactivation in some oligothiophenes with intramolecular charge transfer depending on the solvent polarity and viscosity have been investigated. While for 2-N-piperidino-5-(2',2'-dicyanovinyl)thiophene (PDCVT) the main channel of nonradiative deactivation is the transition to a lower intermediate state with a "twisted" double bond controlled by the medium viscosity, in the case of (E)-{2-[2-5-piperidino-2-thienyl]-6-(triftuoridemethyl)-4H-4-pyranylidene}propanedinitryl (PTFDN) fluorescence quenching is initiated by the solvent polarity. For two other oligothiophenes, 2-N-piperidino-5-cyanothiophene (PCT) and 2-N-piperidino-5"-cyanoterthiophene (PCTT), differing in the length of the thiophene chain, we have revealed, along with the effective quenching of fluorescence in short-chain PCT (independent of the solvent polarity and viscosity), an increase in the radiation capacity in PCTT with increasing polarity of the solvent. The possible mechanisms of nonradiative deactivation in the investigated oligothiophenes are discussed.
- Bondarev, S. L.,Knvukshto, V. N.,Tikhomirov, S. A.,Kalosha, I. I.,Bobrov, S. A.,Masalov, N. V.,Nevar, N. M.,Tyvorskii, N. M.,Kel'in, A. V.,Kulinkovich, O. G.,Dzilinski, K.
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- Efficient indium-mediated dehalogenation of aromatics in ionic liquid media
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An efficient indium-mediated dehalogenation reaction of haloaromatics and haloheteroaromatics in ionic liquids has been studied. This method is simple and effective in the presence of [bmim]Br. Furthermore, this methodology is environmentally friendly compared with conventional ones.
- Canete, Alvaro F.,Salas, Cristian O.,Zacconi, Flavia C.
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- Regioselective photochemical and microwave mediated monobromination of aromatic compounds using 2,4,4,6-tetrabromo-2,5-cyclohexadienone
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Bromination of different aromatic substrates have been described using 2,4,4,6-tetrabromo-2,5-cyclohexadienone in conjunction with microwave and ultraviolet radiations. Important features of the work include high regioselectivity obtained in very short to moderate reaction time, atom economy, and recyclability of the reagent. Copyright Taylor & Francis Group, LLC.
- Gupta, Neeraj,Kad, Goverdhan L.,Singh, Vasundhara,Singh, Jasvinder
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- Toward Functionalized Conducting Polymers: Synthesis and Characterization of Novel β-(Styryl)terthiophenes
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Metal-catalyzed coupling methodologies have been employed in the synthesis of the key building block 3′-formyl-2,2′:5′,2″ -terthiophene. Wittig olefinations with this aldehyde have produced five novel β-styryl-substituted terthiophene monomers. These materials have been fully characterized by NMR spectroscopy, microanalysis, mass spectrometry, and X-ray crystal structure analysis. The results from the UV/visible spectroscopy and cyclic voltammetric investigations are reported.
- Collis, Gavin E.,Burrell, Anthony K.,Scott, Sonya M.,Officer, David L.
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- Dibenzothiophene derivatives as new prototype semiconductors for organic field-effect transistors
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New prototype semiconductor materials based on dibenzothiophene (DBT) derivatives were successfully synthesized by a convergent approach using palladium catalyzed Stille coupling reactions. Thermogravimetric analysis, UV-vis spectra and electrochemistry results indicated these materials had good thermal and photooxidation stability. X-Ray diffraction measurements of the vacuum-evaporated films showed enhanced crystalline order with increasing substrate deposition temperature. The ordered vacuum-evaporated films with charge carrier mobility as high as 7.7 × 10-2 cm2 V-1 s-1 and an on/off ratio of nearly 1 × 10 7 had been achieved with 3,7-bis(5′-hexyl-thiophen-2′-yl) -dibenzothiophene (3,7-DHTDBTT). These results suggest that the 3,7-substituted DBT system is a good prototype for new type organic semiconductors and will play a more important role in organic semiconductors. The Royal Society of Chemistry.
- Gao, Jianhua,Li, Liqiang,Meng, Qing,Li, Rongjin,Jiang, Hui,Li, Hongxiang,Hu, Wenping
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- Nucleophilic C-H Etherification of Heteroarenes Enabled by Base-Catalyzed Halogen Transfer
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We report a general protocol for the direct C-H etherification of N-heteroarenes. Potassium tert-butoxide catalyzes halogen transfer from 2-halothiophenes to N-heteroarenes to form N-heteroaryl halide intermediates that undergo tandem base-promoted alcohol substitution. Thus, the simple inclusion of inexpensive 2-halothiophenes enables regioselective oxidative coupling of alcohols with 1,3-azoles, pyridines, diazines, and polyazines under basic reaction conditions.
- Bandar, Jeffrey S.,Klaus, Danielle R.,Puleo, Thomas R.
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supporting information
p. 12480 - 12486
(2021/08/24)
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- Preparation method of 2-bromothiophene
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The invention discloses a preparation method of 2-bromothiophene, relates to a method for improving thiophene 2-site substitution selectivity and reducing the generation amount of 3-bromothiophene, and belongs to the technical field of preparation of fine
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Paragraph 0027-0036
(2020/10/21)
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- Orthogonal Stability and Reactivity of Aryl Germanes Enables Rapid and Selective (Multi)Halogenations
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While halogenation is of key importance in synthesis and radioimaging, the currently available repertoire is largely designed to introduce a single halogen per molecule. This report makes the selective introduction of several different halogens accessible. Showcased here is the privileged stability of nontoxic aryl germanes under harsh fluorination conditions (that allow selective fluorination in their presence), while displaying superior reactivity and functional-group tolerance in electrophilic iodinations and brominations, outcompeting silanes or boronic esters under rapid and additive-free conditions. Mechanistic experiments and computational studies suggest a concerted electrophilic aromatic substitution as the underlying mechanism.
- Deckers, Kristina,Fricke, Christoph,Schoenebeck, Franziska
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supporting information
p. 18717 - 18722
(2020/08/25)
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- Dehydroxyalkylative halogenation of C(aryl)-C bonds of aryl alcohols
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We herein report Cu mediated side-directed dehydroxyalkylative halogenation of aryl alcohols. C(aryl)-C bonds of aryl alcohols were effectively cleaved, affording the corresponding aryl chlorides, bromides and iodides in excellent yields. Aryl alcohols could serve as both aromatic electrophilic and radical synthetic equivalents during the reaction.
- Liu, Mingyang,Zhang, Zhanrong,Liu, Huizhen,Wu, Tianbin,Han, Buxing
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supporting information
p. 7120 - 7123
(2020/07/14)
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- BIARYL PHENOXY GROUP IV TRANSITION METAL CATALYSTS FOR OLEFIN POLYMERIZATION
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Embodiments are directed to catalyst systems comprising at least one metal ligand complex and to processes for polyolefin polymerization incorporating the catalyst systems. The metal ligand complexes have the following structures:
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- Metal-Free Aerobic Oxidative Selective C-C Bond Cleavage in Heteroaryl-Containing Primary and Secondary Alcohols
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A transition-metal-free aerobic oxidative selective C-C bond-cleavage reaction in primary and secondary heteroaryl alcohols is reported. This reaction was highly efficient and tolerated various heteroaryl alcohols, generating a carboxylic acid derivative and a neutral heteroaromatic compound. Experimental studies combined with density functional theory calculations revealed the mechanism underlying the selective C-C bond cleavage. This strategy also provides an alternative simple approach to carboxylation reaction.
- Xia, Anjie,Qi, Xueyu,Mao, Xin,Wu, Xiaoai,Yang, Xin,Zhang, Rong,Xiang, Zhiyu,Lian, Zhong,Chen, Yingchun,Yang, Shengyong
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supporting information
(2019/05/07)
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- Method for preparing D-(+)-alpha-(2-thiopheneethylamino)-alpha-(2-chlorophenyl)methyl acetate hydrochloride
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The invention provides a novel method for preparing D-(+)-alpha-(2-thiopheneethylamino)-alpha-(2-chlorophenyl)methyl acetate hydrochloride, aiming at solving the technical problems of a traditional synthesis technology of the D-(+)-alpha-(2-thiopheneethylamino)-alpha-(2-chlorophenyl)methyl acetate hydrochloride that the technology is complicated, the cost is high and the yield is low. The method comprises the following steps: 1) preparing 2-bromothiophene; 2) preparing 2-thiopheneethanol; 3) preparing 2-thiopheneethanol p-toluenesulfonate; 4) preparing L-(+)-o-chlorophenylglycine methyl esterL-tartrate; 5) preparing the D-(+)-alpha-(2-thiopheneethylamino)-alpha-(2-chlorophenyl)methyl acetate hydrochloride. The preparation method provided by the invention is low in cost, high in yield andhigh in safety and is suitable for industrial production.
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Paragraph 0009; 0056; 0064-0065; 0074; 0083; 0092; 0101
(2018/12/14)
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- Thiophene oxide derivative and organic light-emitting device thereof
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The invention discloses a thiophene oxide derivative and an organic light-emitting device thereof and belongs to the technical field of organic photoelectric materials. [2,2'-bithiophene]1,1,1',1'-tetroxide is taken as a main body structure, and the pi conjugacy, electrophilicity and charge transfer ability of the material are adjusted through changing a structure and a link method of a ligand, so that the thiophene oxide derivative has high luminous performance, electronic transmission performance, membrane stability and heat stability and high triplet level, and is capable of effectively solving the problem of charge carrier imbalance of unipolar luminescent materials. The luminous efficiency of the organic light-emitting device prepared from the thiophene oxide derivative is strengthened, and the organic light-emitting device is more stable in light and color, has the characteristics of excellent electron chemistry and heat stability and long service life, and also has high luminous efficiency under the condition of low starting voltage.
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Paragraph 0040-0043
(2017/10/13)
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- Synthesis apparatus for 2-bromothiophene
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A synthesis apparatus for 2-bromothiophene. In the apparatus, heated vapor in a thiophene reaction kettle is reacted with bromine vapor in a reaction column to generate a 2-bromothiophene product; the 2-bromothiophene product is directly cooled into liqui
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Paragraph 0032-0035
(2017/09/01)
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- A 2-thiophene acetonitrile with 2-thiophene aminoethane preparation method
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The invention discloses a 2-thiopheneacetonitrile and 2-thiopheneethylamine preparing method. The method is characterized in that by using a palladium catalyst and an organic phosphine ligand, 2-bromothiophene and cyano-acetate are subject to decarboxylat
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Paragraph 0028-0029
(2017/03/28)
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- Catalytic chemical amide synthesis at room temperature: One more step toward peptide synthesis
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An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.
- Mohy El Dine, Tharwat,Erb, William,Berhault, Yohann,Rouden, Jacques,Blanchet, Jér?me
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p. 4532 - 4544
(2015/05/13)
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- Nickel-catalyzed hydrodehalogenation of aryl halides
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In the present study, the nickel-catalyzed dehalogenation of aryl and alkyl halides with iso-propyl zinc bromide or tert-butylmagnesium chloride has been examined in detail. With a straightforward nickel complex as pre-catalyst good to excellent yields and chemoselectivities were feasible for a variety of aryl and alkyl halides.
- Weidauer, Maik,Irran, Elisabeth,Someya, Chika I.,Haberberger, Michael,Enthaler, Stephan
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supporting information
p. 53 - 59
(2013/08/25)
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- TBAF-Catalysed silver oxide-mediated cross-coupling of functional trimethysilylpyridines: Access to arylpyridines and bihetaryl compounds
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The concomitant use of silver oxide and catalytic amount of TBAF allowed the efficient and chemoselective coupling of readily available 4-chloro- and 4-methyl-2-trimethyl-silyl-pyridines with heteroaromatic and aromatic halides. Based on control experiments, a mechanism involving the formation of a pyridylsilver intermediate and TBAF recycling is postulated.
- Louerat, Frederic,Tye, Heather,Napier, Spencer,Garrigou, Michael,Whittaker, Mark,Gros, Philippe C.
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experimental part
p. 1768 - 1773
(2011/04/26)
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- Oxidative bromination of aromatic compounds using O-iodoxybenzoic acid with tetraethylammonium bromide
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A mild and selective procedure for the bromination of activated arenes using o-iodoxybenzoic acid and tetraethylammonium bromide is presented. The reactions were carried out at room temperature and gave moderate to excellent yields. Copyright Taylor & Francis Group, LLC.
- Bhalerao, Dinesh S.,Mahajan, Ulhas S.,Akamanchi, Krishnacharya G.
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experimental part
p. 2814 - 2819
(2009/04/04)
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- Synthesis of 2,3-Substituted Thienylboronic Acids and Esters
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A noncryogenic protocol for the synthesis of 2-substituted 3-thienylboronic acids and esters as well as 3-substituted 2-thienylboronic acids and esters has been developed. Electrophiles were introduced regiospecifically in the 2-position of 2,3-dibromothiophene and in the 3-position of 2-bromo-3-iodothiophene by halogen-magnesium exchange followed by quenching with electrophiles. Palladium-catalyzed borylation of the 2,3-substituted halothiophenes with pinacolborane and P(t-Bu)3 as ligand for Pd produced 9 and 10. The borylation protocol was tolerated by a range of functional groups; however, strongly electron-withdrawing substituents decreased the stability of the thienylboronic acids and esters.
- Christophersen, Claus,Begtrup, Mikael,Ebdrup, Soren,Petersen, Henning,Vedso, Per
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p. 9513 - 9516
(2007/10/03)
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- Method of treating or preventing urinary incontinence using prostanoid EP1 receptor antagonists
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This invention encompasses a method of treating or preventing urinary incontinence in a mammalian patient comprising administering to the patient a compound of formula I: or a pharmaceutically acceptable salt, hydrate or ester thereof. The invention also encompasses certain pharmaceutical compositions and methods for treatment of prostaglandin mediated diseases comprising the use of compounds of formula I.
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- Neuroprotective pharmaceutical composition containing stereoisomers of arylcyclohexylamines
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The invention relates to pharmaceutical compositions for neuroprotection containing the compound (1S,2R) 1-[1-(2-thienyl)-2-alkylcyclohexyl]piperidine or (1S,2R) 1-[1-(2-furanyl)-2-alkylcyclohexyl]piperdine, or their pharmaceutically acceptable salts. The synthesis and method separation of racemic mixtures to provide pure enantiomers is presented. The compositions have use in the treatment of stroke, CNS trauma and Alzheimer's disease.
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- Anisotropic organic compounds
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STR1 The invention describes liquid crystalline compounds or formula (I), where A, D and G are independently selected from phenyl, thiophene, hydrogenated phenyl, chlorinated phenyl and fluorinated phenyl, B and E are independently selected from a single bond C= C. C C.C00, azoxy and diazo, k and m are independently selected from 1 and 0, such that m+n is 1 or 2, and R1 and R2 are independently selected from R, R0, alkynyl, thioalkyl, hydrogen, CN, NCS and SCN; provided that at least one of R1 and R2 is selected from CN, NCS and SCN and that at least one of A, D and G is phenyl; and excluding where at least one of R1 and R2 is independently selected as CN and one of A, D or G is not thiophene, and where m is 0, A, and D are phenyl, B is a single bond and only one of R1 or R2 is NCS. Also described are compounds suitable for inclusion in a device utilizing pretransitional characteristics of liquid crystalline materials in the isotropic phase, of general formula (II) where J and Y are independently selected from phenyl, thiophene, hydrogenated phenyl, chlorinated phenyl and fluorinated phenyl, X is selected from C= C. C C.COO azoxy and diazo, k is 1 or 0 and R3 and R4 are independently selected from R, RO, alkynyl, thioalkyl, hydrogen, CN, NCS and SCN; provided that at least one of R3 and R4 is selected from CN, NCS and SCN and that at least one of J and Y is phenyl.
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- Pharmaceutical compositions for neuroprotection containing arylcyclohexylamines
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The invention relates to pharmaceutical compositions for neuroprotection containing arylcyclohexylamines. These compositions comprise an arylcyclohexylamine in accordance with the formulas: STR1 in which: R 1 represents STR2 with R 4 being a hydrogen atom, a fluorine atom, an iodine atom or a methyl radical, R 2 stands for a hydrogen atom, the radical OH or the radical CH 3 and R 3 stands for hydrogen atom or the radical CH 2 R 5 with R 5 representing H, OH, Cl, Br or CH 3 COO, provided that R 2 and R 3 are not both a hydrogen atom, or an addition salt to a pharmaceutically acceptable acid of said arylcyclohexylamine.
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- NOVEL HALOGENATION OF THIOPHENES WITH BENZENESELENINYL CHLORIDE AND ALUMINUM HALIDE
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In the presence of aluminum halide, benzeneseleninyl chloride is an efficient regioselective halogenating reagent for heterocyclic compounds such as thiophene, 2-methylthiophene, 3-methylthiophene, 2,5-dimethylthiophene, and furan.In the case of pyrrole, no halogenated product was obtained.A plausible reaction mechanism involving a positive halogen intermediate is proposed.
- Kamigata, Nobumasa,Suzuki, Takashi,Yoshida, Masato
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- A Large-Scale Procedure for the Preparation of 3-Bromothiophene from 2-Bromothiophene and Sodamide in Liquid Ammonia
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3-Bromothiophene can be prepared on a scale of several moles by treatment of 2-bromothiophene with an excess of sodamide in liquid ammonia and subsequent quenching of the reaction mixture with solid ammonium chloride.
- Brandsma, L.,Jong, R.L.P. de
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p. 1697 - 1700
(2007/10/02)
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- Preparation of biaryl compounds
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A method for the preparation of biaryl compounds is disclosed which comprises contacting an aromatic halide in the presence of a catalyst comprising zerovalent nickel, a bidentate phosphorus-containing coordinating ligand and a reducing metal in a polar, aprotic solvent system for a time and under conditions suitable for the formation of biaryl compound.
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- Charge Density - Activation Energy Correlations in Bromination of Thiophenes by N-Bromosuccinimide in Solution
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The activation energies for N-bromosuccinimide bromination of several thiophene derivatives in 80percent (v/v) aqueous acetic acid have been determined and discussed in the light of electron densities at the reaction site.The effect of substituents at different positions of thiophene ring has been investigated quantitatively by the actual calculation of total (? + ?) charge densities at various positions of the substituted thiophenes.
- Rajaraman, Lalitha,Nanjan, M. J.
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p. 538 - 539
(2007/10/02)
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- Novel Bromination Reagents. Electrophilic Aromatic Bromination by Hexabromocyclopentadiene
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Hexabromocyclopentadiene efficiently and regioselectively brominates activated aromatic compounds, in a process which is interpreted as involving ready formation of the pentabromocyclopentadienide anion by bromonium ion release.
- Fuchs, Benzion,Belsky, Yigal,Tartakovsky, Evgeny,Zizuashvili, Jakob,Weinman, Sarah
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p. 778 - 779
(2007/10/02)
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- Charge Density - Activation Energy Correlations in Electrophilic Bromination of Thiophenes
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Charge density calculations are made on eleven thiophenes by Hueckel LCAO MO and Del Re methods and correlated with experimental activation energies(Ea) obtained for the molecular bromination of these compounds.The need for the inclusion of ?-charges in any correlation of charge density with kinetic data is stressed. - Keywords: Charge density/ Activation energy / Bromination of thiophenes
- Nanjan, M. J.,Kannappan, V.,Ganesan, R.
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- THE RATES OF BASE CLEAVAGE OF SUBSTITUTED 2-THIENYLTRIMETHYLSILANES. AB INITIO CALCULATIONS OF THE ACIDITIES OF MONOSUBSTITUTED THIOPHENS
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Rates of cleavage in NaOMe-MeOH at 50 deg C have been determined for the mono-substituted 2-trimethylsilylthiophens X*C4H2S*SiMe3-2 with X = H, 3-NO2, 3-Br, 4-Br-, and 5-NO2, -CN, -COPh, -Me, -OMe and -NMe2, and for one disubstituted compound, 4,5-Br2*C4HS*SiMe3-2.For several compounds the rate and product isotope effects have also been determined.The energies involved in the process X*C4H3S X*C4H2S- for deprotonation at the 2-position have been calculated by an ab initio method (STO-3G), and the results used in analysis of the substituent effects in the cleavage of the XC4H2S*SiMe3-2 compounds.The results are consistent with the view the aryl anions separate in the rate-determining step of the cleavage.The isotope effects are all close to unity, whereas by comparison with results for XC6H4CH2SiMe3 and related species of similar reactivity, values in the region of 10 would be expected for the 3- and 5-NO2 compounds if the product isotope effect for a carbanion R depended only in the pKa of RH.The difference between the thienyl- and benzyl-type anions is attributed to the absence of conjugative delocalization of the charge in the former. Approximate pKa values are derived for the 2-positions of the X*C4H3S compounds.
- Seconi, Giancarlo,Eaborn, Colin,Stamper, John G.
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p. 153 - 168
(2007/10/02)
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- Kinetics of Bromination of Certain Substituted Thiophenes in Solution
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The general features of the kinetics of bromination of thiophene and substituted thiophenes have been investigated in dry and 15percent aq. acetic acid (v/v) and the Arrhenius activation energy (Ea) accurately determined for ten thiophene derivatives and interpreted.The mechanism proposed is supported with the detection of a ?-complex between bromine and 2-bromothiophene.
- Kannappan, V.,Nanjan, M. J.,Ganesan, R.
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p. 1183 - 1187
(2007/10/02)
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- Substituted thiophenes
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3,5-Bis(t-butyl)-4-hydroxyphenyl- and 3,5-bis(t-butyl)-4-hydroxybenzoyl-substituted thiophenes have valuable pharmacological acitivity as antiinflammatory agents.
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- Sulfonation of aromatic compounds in the presence of solvents
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A process for the sulfonation of aromatic compounds wherein an aromatic substance consisting of one or more aromatic compounds susceptible to the action of sulfur trioxide is formed into a reactant by admixture with one or more organic liquids, substantially inert to sulfur trioxide under the conditions of the process, which reactant is brought to boiling at a temperature not greater than 100° C under a pressure of from 0.1 mm Hg to atmospheric pressure, gaseous sulfur trioxide is introduced thereinto thereby causing it to continue to boil, the component or components of the reactant thus volatilized is or are reconverted to liquid in a heat-exchanger and recycled to the reaction chamber, and the pressure in the reaction chamber and the rate at which the gaseous sulfur trioxide is introduced into the reactant are controlled so as to ensure that there is always present in the reaction chamber an amount of volatilizable matter exceeding that amount volatilizable by the heat of reaction of the aromatic substance present in the reaction chamber with the gaseous sulfur trioxide in contact with said aromatic substance and that the temperature of the reaction mixture is a temperature of 100° C or below.
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