- Activator free, expeditious and eco-friendly chlorination of activated arenes by N-chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI)
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N-Chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI) has been explored for the first time as a chlorinating reagent for direct chlorination of various activated arenes and heterocycles without any activator. A comparative in-silico study was performed to determine the electrophilic character for NCBSI and commercially available N-chloro reagents to reveal the reactivity on a theoretical viewpoint. The reagent was prepared by an improved method avoiding the use of hazardous t-butyl hypochlorite. This reagent was proved to be very reactive compared to other N-chloro reagents. The precursor of the reagent N-(phenylsulfonyl)benzene sulfonamide was recovered from aqueous spent, which can be recycled to synthesize NCBSI. The eco-friendly protocol was equally applicable for the synthesis of industrially important chloroxylenol as an antibacterial agent.
- Misal, Balu,Palav, Amey,Ganwir, Prerna,Chaturbhuj, Ganesh
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supporting information
(2021/01/04)
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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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- Highly-chemoselective step-down reduction of carboxylic acids to aromatic hydrocarbons: Via palladium catalysis
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Aryl carboxylic acids are among the most abundant substrates in chemical synthesis and represent a perfect example of a traceless directing group that is central to many processes in the preparation of pharmaceuticals, natural products and polymers. Herein, we describe a highly selective method for the direct step-down reduction of carboxylic acids to arenes, proceeding via well-defined Pd(0)/(ii) catalytic cycle. The method shows a remarkably broad substrate scope, enabling to direct the classical acyl reduction towards selective decarbonylation by a redox-neutral mechanism. The utility of this reaction is highlighted in the direct defunctionalization of pharmaceuticals and natural products, and further emphasized in a range of traceless processes using removable carboxylic acids under mild, redox-neutral conditions orthogonal to protodecarboxylation. Extensive DFT computations were conducted to demonstrate preferred selectivity for the reversible oxidative addition and indicated that a versatile hydrogen atom transfer (HAT) pathway is operable.
- Liu, Chengwei,Qin, Zhi-Xin,Ji, Chong-Lei,Hong, Xin,Szostak, Michal
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p. 5736 - 5742
(2019/06/18)
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- Synthesis method of 2-thiopheneacetic acid
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The invention provides a synthesis method of 2-thiopheneacetic acid. The synthesis method comprises the following steps: by taking thiophene as a raw material, chloridizing, iodizing, condensing with diethyl malonate, and finally hydrolyzing and heating for decarboxylation, so that 2-thiopheneacetic acid is obtained. The synthesis method provided by the invention is simple to operate, reaction process can be easily controlled, a highly toxic reagent does not need to be used, safety coefficient is high, the adopted raw material is cheap and easily available, pollution is low, requirement on production equipment is low, production cost is low, produced 2-thiopheneacetic acid is white solid powder, purity is more than or equal to 99.0%, product quality is good, and yield is high, so that the synthesis method is applicable to industrial production.
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Paragraph 0028; 0051; 0052
(2017/01/26)
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- Iron(III)-mediated photocatalytic selective substitution of aryl bromine by chlorine with high chloride utilization efficiency
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An iron(III)-mediated photocatalytic method for the conversion of aryl, heteroaryl and polycyclic aromatic bromides to the corresponding chlorides with high selectivity has been achieved successfully. The mild reaction conditions and high chloride utilization efficiency promise a bright future for chlorination reactions. The Royal Society of Chemistry 2014.
- Wang, Ying,Li, Lina,Ji, Hongwei,Ma, Wanhong,Chen, Chuncheng,Zhao, Jincai
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supporting information
p. 2344 - 2346
(2014/03/21)
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- Halogenation of Aromatic Compounds by N-chloro-, N-bromo-, and N-iodosuccinimide
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An efficient and mild method for the halogenation of aromatic compounds using N-chloro-, N-bromo-, and N-iodosuccinimide in the presence of NH 4NO3 or FeCl3 in acetonitrile was developed.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
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p. 932 - 933
(2007/10/03)
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- A convenient catalytic route to symmetrical functionalized bithiophenes
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A series of symmetrical functionalized bithiophenes has been synthesized in good to excellent yields via homocoupling of thiophene halides in the presence of Pd(OAc)2 as a catalyst.
- Hassan, Jwanro,Lavenot, Laurence,Gozzi, Christel,Lemaire, Marc
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p. 857 - 858
(2007/10/03)
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- Competitive reactivities of vinylthiyl radicals thermally generated from haloethylenes and hydrogen sulfide
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Acetylene and its derivatives have been used for the first time as "traps" for vinylthiyl radicals generated in situ from hydrogen sulfide and haloethylenes in gas-phase processes. The competitive reactivity of the vinylthiyl radicals has been studied at 500-570 °C in the presence of two chemical "traps." The efficiency of chemical "traps" for the vinylthiyl radicals decreases in the following sequence: HC≡CPh > HC≡CH > MeC≡CH > CH2=CHCl. Acetylene is a more efficient "trap" for the vinylthiyl radicals than 1,2-dichloroethylene, from which they have been generated. The β-phenylvinylthiyl radicals generated during cothermolysis of halostyrene-hydrogen sulfide-acetylene component ternary systems undergo first of all intramolecular ring closure to give benzothiophene, which is a thermodynamically favorable system; the reaction of these radicals with acetylene and its derivatives occurs much more slowly than heterocyclization. Phenylacetylene is a more efficient "trap" than acetylene. α-Phenylvinylthiyl radicals mostly react with acetylene to yield 2-phenylthiophene.
- Deryagina,Sukhomazova,Levanova
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p. 662 - 666
(2007/10/03)
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- Reevaluation of benzyltrimethylammonium dichloroiodide, previously reported to be a selective iodinating agent
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Benzyltrimethylammonium dichloroiodate, previously reported as an iodinating agent of thiophenes, appears to be a selective chlorinating agent of both thienyl and furyl derivatives containing a carbonyl group.
- D'Auria,Mauriello
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p. 248 - 250
(2007/10/02)
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- Nickel catalyst for the cyanation of aromatic halides
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The invention relates to a nickel compound to be used as a catalyst for cyanation reactions, said nickel compound having a central nickel atom complexed by a diphosphine ligand. In said diphosphine ligand the P-atoms are interconnected through an aliphatic, cycloaliphatic or aromatic bivalent radical. The invention also relates to the use of said nickel compound and to a method of preparing an aromatic cyanide from an aromatic halide and an alkali metal cyanide in a substantially anhydrous non-dipolar aprotic solvent under the influence of a phosphine-nickel catalyst and in the presence of a salt of a transition metal.
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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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p. 3072 - 3075
(2007/10/02)
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- COMPOSITION OF REACTION MIXTURES IN THE OXIDATIVE CHLORINATION OF THIOPHENE IN THE SYSTEM HYDROGEN PEROXIDE - HYDROCHLORIC ACID
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The chlorination of thiophene in the system hydrogen peroxide-hydrochloric acid was investigated in order to find the conditions under which mixtures of thiophene and 2-chlorothiophene can be obtained with a relatively high content of chlorothiophene but
- Rudakova, N. I.,Anufrieva, O. V.,Smirnova, E. A.
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p. 1887 - 1890
(2007/10/02)
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- Anti-inflammatory thienylbenzylamine compounds
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Novel thienylbenzylamine compounds of the formula STR1 wherein A and R1 -R5 are defined herein. These compounds are useful for the treatment of inflammation.
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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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- PROTONATION AND ELECTROPHILIC TRICHLOROMETHYLATION OF 2,5- AND 2,4-DICHLOROTHIOPHENES
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Trichloromethylation of 2,5-dichlorothiophene, 1, and 2,4-dichlorothiophene, 2, with CCl4 and AlCl3 has been studied.It could be shown that in the case of 1 the reaction was directed to position 3 with formation of 2,5-dichloro-3-(trichloromethyl)thiophene, 3, the process being complicated by the formation of the isomeric 3,5-dichloro-2-(trichloromethyl)thiophene, 4, and 4,5-dichloro-2-(trichloromethyl)thiophene, 5, as well as linked products, i.e. a mixture of bis(dichlorothienyl)dichloromethanes (6).Trichloromethylation of 3 smoothly leads to 4, along with a small amount of bis(3,5-dichloro-2-thienyl)dichloromethane.It has also been found that, as a result of protonation, under the effect of HCl and AlCl3, the 2,5-dichloro derivative 1 was converted into the 2,4-dichloro isomer 2, which, under the reaction conditions, exist in the form of ?-complex, i.e. the 2H-3,5-dichlorothiophenium ion, stable at room temperature.The mechanism of trichloromethylation of 1, including the ipso-attack by the CCl3+ cation and isomerization during protonation, is discussed.
- Belen'kii, Leonid I.,Gromova, Galina P.,Krayushkin, Mikhail M.
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p. 365 - 368
(2007/10/02)
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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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- 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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p. 2017 - 2020
(2007/10/02)
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- Preparation of 2-Chlorofuran and 2-Chlorothiophene from the Respective Furan and Thiophene Mercurials and Disulfur Dichloride
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2-Chloro- and 2-iodo-substituted furans and thiophenes (with no admixture of higher halogenated products) have been obtained from 2,2'-difurylmercury or 2,2'-dithienylmercury by the action of either a solution of freshly-redistilled S2Cl2 in carbon disulfide or an aqueous solution of KI3, in 60-70percent isolated yields. 2-Chlorofuran and 2-chlorothiophene may also be obtained by the direct action of either furan or thiophene on a mixture of HgCl2 and S2Cl2, in 50percent and 60percent isolated yields, respectively.
- Khodeir, Mohammed N. M.,Skulski, Lech,Wroczynski, Piotr
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p. 443 - 448
(2007/10/02)
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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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p. 130 - 133
(2007/10/02)
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- 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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p. 931 - 934
(2007/10/02)
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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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- 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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