共查询到20条相似文献,搜索用时 46 毫秒
1.
Salo Gronowitz Marcel Temciuc Anna-Britta Hrnfeldt 《Journal of heterocyclic chemistry》1993,30(4):1111-1116
Reaction between various thienyllithium derivatives and dimethyl disulfide has been used for the preparation of 2,5-, 2,3-, and 3,4-bis(methylthio)thiophenes, as well as 2,3,4- and 2,3,5-tris(methylthio)thiophenes. Bromination of (methylthio)thiophenes with N-bromosuccinimide was found to be most convenient for the preparation of brominated (methylthio)thiophenes such as 3-bromo-2,5-bis(methylthio)- and 5-bromo-2,3-bis(methylthio)thiophene, 3,4-dibromo-2,5-bis(methylthio)-, 2,5-dibromo-3,4-bis(methylthio)- and 2,3-dibromo-4,5-bis(methylthio)thiophene as well as 3-bromo-2,4,5-tris(methylthio)thiophene. The reaction of methylthio substituted thienyllithium derivatives with methyl chloroformate was used for the syntheses of methyl methylthio substituted thiophenecarboxylates and using 1/3 of an equivalent for the direct preparation of methylthio substituted 3-thienylcarbinols as tris[2,4,5-tris(methylthio)-3-thienyl]carbinol. 相似文献
2.
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate the reduction of some mono-, di-, tri-, and tetrahalopyrimidines at mercury cathodes in acetonitrile containing tetramethylammonium tetrafluoroborate. Two irreversible cyclic voltammetric waves are observed for reduction of 2-bromo-, 5-bromo-, and 2-chloropyrimidine; the first wave is due to cleavage of the carbon---halogen bond, and the second wave is attributable to reduction of pyrimidine. Cyclic voltammograms for 2,4-dichloro- and 4,6-dichloropyrimidine exhibit three cathodic waves, whereas that for 2,4,6-trichloropyrimidine shows four cathodic waves, arising from sequential cleavage of carbon---chlorine bonds as well as the reduction of pyrimidine. For the reduction of 2,4,5,6-tetrachloropyrimidine, a cyclic voltammogram exhibits four major irreversible cathodic waves corresponding to the cleavage of carbon---chlorine bonds, but the wave for reduction of pyrimidine is poorly defined. Bulk electrolyses of halopyrimidines at potentials for different stages of reduction lead to products that are consistent with expectations based upon cyclic voltammetry. In addition, our findings agree well with theoretical calculations of the relative stabilities of the various reduction intermediates. Mechanistic aspects of the reduction of halopyrimidines are discussed and, using homogeneous redox catalysis, we have determined the lifetimes of the electrogenerated radical-anions of 2-bromo- and 2-chloropyrimidine. 相似文献
3.
Hajime Sugita Yoshihiro Ohta Tsutomu Yokozawa 《Journal of polymer science. Part A, Polymer chemistry》2020,58(9):1236-1240
Suzuki-Miyaura cyclic polycondensation of 1.3 equivalents of thiophene dibromide or pyridine dibromide with 1.0 equivalent of phenylenediboronic acid ester was investigated in the presence of t-Bu3PPd G2 precatalyst, which generates t-Bu3PPd(0), and CsF/18-crown-6 as a base. Polycondensation of 2,5-dibromothiophene and 5,5′-dibromo-2,2′-bithiophene with pinacol meta-phenylenediboronate ( 2 ) yielded corresponding cyclic polymers. On the other hand, polycondensation of 3,4-dibromothiophene with para-phenylenediboronate ( 5 ) gave linear polymer with bromothiophene at both ends via conventional unstoichiometric polycondensation involving excess dibromo monomer, implying that intramolecular catalyst transfer did not proceed effectively on 3,4-dibromothiophene. A model reaction of 3,4-dibromothiophene with phenylboronic acid indeed gave monosubstituted thiophene preferentially via intermolecular catalyst transfer. In the polycondensation of excess pyridine dibromide with 5 , the use of 2,6-dibromopyridine gave linear polymer, whereas the use of 3,5-dibromopyridine yielded cyclic polymer. Thus, the position of bromine in heteroarylenes determines whether cyclic polymer or linear polymer is formed, in contrast to the case of unstoichiometric Suzuki-Miyaura cyclic polycondensation with dibromophenylenes. 相似文献
4.
Yoshiro Kobayashi Kosuke Kawada Akira Ando Itsumaro Kumadaki 《Tetrahedron letters》1984,25(18):1917-1920
The photolysis of 2,3-bis(trifluoromethyl)thiophene gave an equilibrium mixture of 2,3- and 3,4-bis(trifluoromethyl)Dewar thiophenes, while that of 2,5-bis(trifluoromethyl)thiophene gave 2,4-bis(trifluoromethyl)-thiophene, which seemed to be formed through an intermediate other than the Dewar form. 相似文献
5.
Pd-catalyzed multifold (2-, 3-, and 4-fold) carbon-sulfur cross-coupling reaction of indium tri(organothiolates) with polybromonated aromatic and heteroaromatic compounds was developed in a one-pot procedure. Both 2,5-dibromopyridine and 2,6-dibromopyridine reacted with indium tri(organothiolates) (0.68 equiv) in the presence of 4 mol % of Pd(OAc)(2), 4.2 mol % of Xantphos, and 1 equiv of diisopropylethylamine (DIPEA), producing disulfides in good to excellent yields. These results indicate that indium tri(organothiolates) transfer all three alkyl- or arylthio groups attached to indium metal to electrophilic coupling partners. Indium tri(organothiolates) derived from alkyl thiol having a low boiling point, such as n-propyl, isopropyl, and tert-butyl thiol, acted as good nucleophilic coupling partners. In addition, indium tri(arylthiolates) derived from aryl thiols possessing an electron-withdrawing or -donating group on the aromatic ring participated well in the Pd-catalyzed multifold carbon-sulfur cross-coupling reaction. 4,4'-Dibromo-1,1'-biphenyl, 9,10-dibromoanthracene, 2,4-dibromoanisole, 2,7-dibromo-9,9-dimethylfluorene, 3,4-dibromothiophene, 2,3-dibromothiophene, 2,2'-bithiophene, 1,3,5-tribromobenzene, and 1,2,4,5-tetrabromobenzene were converted smoothly to the corresponding di-, tri-, and tetrasulfides. 相似文献
6.
Nechepurenko I. V. Shul'ts E. E. Tolstikov G. A. 《Russian Journal of Organic Chemistry》2003,39(10):1436-1450
The Diels-Alder reaction of new 1-(3,4-dimethoxyphenyl)- or 1-(2,4-dimethoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2,5- and 2,6-dibromo-, and 2-bromo-6-methyl-1,4-benzoquinones regioselectively yields substituted 7-hydroxy-5-(dimethoxyphenyl)-1,4-naphthoquinones. By cycloaddition of the siloxydienes to naphthoquinone, bromonaphthoquinone, and juglone the corresponding substituted 3-hydroxy-1-(dimethoxyphenyl)-9,10-anthraquinones or their 4,4a-dihydro or 1,1a,4,4a-tetrahydro derivatives were obtained. 相似文献
7.
运用密度泛函理论(DFT),采用Mo16S32团簇模型,在PW91/DNP水平上研究了噻吩(TP)及一系列烷基噻吩类硫化物如2-甲基噻吩(2-MT)、3-甲基噻吩(3-MT)、2,3-二甲基噻吩(2,3-DMT)、2,4-二甲基噻吩(2,4-DMT)、2,5-二甲基噻吩(2,5-DMT)及3,4-二甲基噻吩(3,4-DMT)等在加氢脱硫催化剂MoS2上的吸附行为.结果表明,在η1S吸附构型中,Mo16S32团簇对烷基噻吩吸附能力的顺序为2,5-DMT>2,4-DMT≈2,3-DMT>2-MT>3,4-DMT>3-MT>TP.通过键长、Mayer键级、Mulliken电荷分析可知,当噻吩环的2-或5-位不含甲基时,吸附能随硫原子电荷密度的增加而增大;2-或5-位含甲基时,甲基与团簇上相邻的Mo原子发生了弱的相互作用,使吸附能增大;虽然2,5-DMT的2-和5-位均含有甲基,但甲基离团簇上相邻的Mo较远,相互作用较小,吸附能较2,3-DMT和2,4-DMT增加的较少.文中还对各硫化物在MoS2催化剂上的加氢脱硫反应进行了讨论. 相似文献
8.
Starting from 2,5-dichlorothiophen many new 3,4-disubstituted thiophens have been made including the dialdehyde. Treatment of this with phosphorus pentabromide could be made to give 2,5-dichloro-3- dibromomethylthiophen-4-aldehyde, 2,5-dichloro- or 2-bromo-5-chloro-3,4-bisdibromomethylthiophen. the latter two compounds reacted with sodium iodide to give the corresponding cis- and trans-3,4-dibromo cyclobuteno[c]thiophen derivatives (18–21). Reaction of trans-3,4-dibromo-2,5-dichlorocyclobuteno[c]thiophen with N-bromosuccinimide resulted in fission of the 4-membered ring regenerating 2,5-dichloro-3,4-bisdibromomethylthiophen.When 2,5-dichloro-3,4-di-iodothiophen was treated with butyl-lithium followed by dimethylsulphate it gave 2,5- dichloro-3,4-dimethylthiophen together with a low yield of a red compound which is considered to be a dichloro dimethyl derivative (11) of bisthiophenindigo.Several unsuccessful approaches to the synthesis of dithiophen analogues of biphenylene are outlined. These included heating various 3,4-di-iodothiophens and 4,4′-di-iodo-3,3′-bithienyls with copper as well as the flash vacuum pyrolysis of the latter compounds, of thiophen-3,4-dicar?ylic anhydrides and of 2,5-dichloro-3-iodothiophen-4-car?ylic acid. 相似文献
9.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1992,48(10):1481-1489
The Raman and Fourier transform infrared spectra of 2,3-dichloro-, 2,4-dichloro-, 2,5-dichloro-, 3,4-dichloro-, 3,5-dichloro-, 2,3,4-trichloro-, 2,4,5-trichloro-, 2,4,6-trichloro-, 2,3,5,6-tetrachloro- and pentachloronitrobenzene were recorded. Raman polarization measurements were made wherever possible. A normal coordinate analysis was carried out for both the in-plane and out-of-plane vibrations of these molecules using a 59-parameter modified valence force field. The force constants were refined using an Overlay least-squares technique employing 352 frequencies of 10 molecules. The reliability of the force constants so obtained was tested by making a zero-order calculation for p-, m- and o-dinitrobenzenes, 1-fluoro-, 1-chloro- and 1-bromo-, 2,4-dinitrobenzenes, 2,4-difluoro- and 2,5-difluoro- and 2,5-dibromonitrobenzenes. Unambiguous vibrational assignments of all the fundamentals were made using the potential energy distribution and eigen vectors. 相似文献
10.
A. V. Trukhin A. V. Messorosh V. S. Karavan E. V. Eliseenkov 《Russian Journal of Organic Chemistry》2007,43(6):801-811
The mechanism of radical alkylation of 3,4-dichloro-2,5-dihydrofuran-2,5-dione with cyclohexane and 2,3-dimethylbutane follows an addition-elimination pattern with reversible formation of alkyl radicals. The proposed kinetic scheme takes into account the possibility for isomerization of primary 2,3-dimethylbutane radicals into tertiary and is consistent with the experimental data. The regioselectivity of the process is linearly related to the concentration of hydrogen chloride, so that the rate constant for the addition of primary 2,3-dimethylbutane radical to 3,4-dichloro-2,5-dihydrofuran-2,5-dione may be estimated. Effective procedures for the synthesis of 3-chloro-4-(2,3-dimethylbut-2-yl)-, 3-chloro-4-cyclohexyl-, and 3,4-dicyclohexyl-2,5-dihydrofuran-2,5-diones have been proposed. 相似文献
11.
E. A. Chernyshev N. G. Komalenkova G. N. Yakovleva V. G. Bykovchenko M. A. Dubikhina V. G. Lakhtin 《Russian Journal of General Chemistry》2007,77(8):1332-1336
Gas-phase reactions of dichlorogermylenes formed in the GeCl4-Si2Cl6 system with 2-chlorothiophene, 2,5-dichlorothiophene, 2,5-dichloro-3-methylthiophene, and 5-chloro-2-trimethylsilylthiophene is studied. It is shown that :GeCl2 is inserted into the chlorothiophene C-Cl bond to form the derivatives containing one or two trichlorogermyl groups. In the reaction with 5-chloro-2-trimethylsilylthiophene, the insertion of :GeCl2 into the C-Cl bond yielding 5-trichlorogermyl-2-trimethylsilylthiophene is accompanied by the exchange of the Me3Si group with the trichlorogermyl group to form 2,5-bis(trichlorogermyl)thiophene. The reactions occurring in the course of the synthesis of thienylchlorogermanes are considered. 相似文献
12.
On the Synthesis of Sulfonated Derivatives of 2,3-Dimethylaniline and 3,4-Dimethylaniline Baking the hydrogensulfate salt of 2,3-dimethylaniline ( 1 ) or of 3,4-dimethylaniline ( 2 ) led to 4-amino-2,3-dimethylbenzenesulfonic acid ( 4 ) and 2-amino-4,5-dimethylbenzenesulfonic acid ( 5 ), respectively (Scheme 1). The sulfonic acid 5 was also obtained by treatment of 2 with sulfuric acid or by reaction of 2 with amidosulfuric acid. 3-Amino-4,5-dimethylbenzenesulfonic acid ( 3 ) and 5-Amino-2,3-dimethylbenzenesulfonic acid ( 6 ) were prepared by sulfonation of 1,2-dimethyl-3-nitrobenzene ( 9 ) to 3,4-dimethyl-5-nitrobenzenesulfonic acid ( 11 ) and of 1,2-dimethyl-4-nitrobenzene ( 10 ) to 2,3-dimethyl-5-nitrobenzenesulfonic acid ( 12 ), respectively, with subsequent Béchamp reduction (Scheme 1). Preparations of 2-amino-3,4-dimethylbenzenesulfonic acid ( 7 ) and of 6-amino-2,3-dimethylbenzenesulfonic acid ( 8 ) were achieved by the sulfur dioxide treatment of the diazonium chlorides derived from 3,4-dimethyl-2-nitroaniline ( 24 ) and from 2,3-dimethyl-6-nitroaniline ( 31 ) to 3,4-dimethyl-2-nitrobenzenesulfonyl chloride ( 29 ) and 2,3-dimethyl-6-nitrobenzenesulfonyl chloride ( 32 ), respectively, followed by hydrolysis to 3,4-dimethyl-2-nitrobenzenesulfonic acid ( 30 ) and 2,3-dimethyl-6-nitrobenzenesulfonic acid ( 33 ), and final reduction (Scheme 3). Compound 7 was also synthesized by reaction of 4-chloro-2,3-dimethylaniline ( 23 ) with amidosulfuric acid to 2-amino-5-chloro-3,4-dimethylbenzenesulfonic acid ( 20 ) and subsequent hydrogenolysis (Scheme 2). 4′-Bromo-2′, 3′-dimethyl-acetanilide ( 13 ) and 4′-chloro-2′, 3′-dimethyl-acetanilide ( 14 ) on treatment with oleum yielded 5-acetylamino-2-bromo-3,4-dimethylbenzenesulfonic acid ( 17 ) and 5-acetylamino-2-chloro-3,4-dimethylbenzenesulfonic acid ( 18 ), respectively. Their structures were proven by hydrolysis to 5-amino-2-bromo-3,4-dimethylbenzenesulfonic acid ( 21 ) and 5-amino-2-chloro-3,4-dimethylbenzenesulfonic acid ( 22 ), followed by reductive dehalogenation to 3 . 相似文献
13.
The electrochemical reduction of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDT) is studied with the aid of cyclic voltammetry and electrolysis at a constant potential on a glassy-carbon electrode in a 0.1 M solution of Bu4NBF4 in dimethylformamide. Cyclic voltamograms for DBEDT exhibit two irreversible peaks corresponding to successive abstraction of bromine atoms. Electrolysis at potentials more negative than the potential of the first peak and more positive than the potential of the second peak leads to the formation of an electrochemically active film of poly(3,4-ethylenedioxythiophene) (PEDT). Cathodic polymerization of dibromothiophene with the formation of an electroactive film is performed for the first time ever without a catalyst. The poor stability of the film is attributed to the presence of exceedingly unstable monobromo-3,4-ethyl-enedioxythiophene in it. PEDT, obtained from DBEDT with the aid of thermal polymerization, forms a stable electrochemically active film when rubbed onto a glassy-carbon electrode. 相似文献
14.
LIU Zhong-Li ZHANG Mao-Xi CHEN Yi-Wen YANG Li LIU You-ChengNational Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou Gansu China 《中国化学》1994,12(5):456-463
A series of novel oligo(halobenzoquinoid) compounds have been obtained from the photoinduced self-substitution of 2,5-dibromo-1,4-benzoquinone (1a), 2,6-dibromo-1,4-benzoquinone (1b), 2-chloro-1,4-benzoquinone (1c), 2-bromo-5-chloro-1,4-benzoquinone (1d), 2,3,5,6-tetrachloro-1,4-benzoquinone (1e) and 1,4-benzoquinone (1f) in the presence of N,N-dimethyl-t-butylamine (2) in acetonitrile. Dimers, trimers and/or pentamers of these haloquinones were found to be the major products. 相似文献
15.
在冰浴条件下, 2-甲基噻吩(1)与液溴反应生成3,5-二溴-2-甲基噻吩(2); 在-78 ℃条件下, 硼酸三丁酯加入2, 得到2-甲基-3-溴-5-硼酸基噻吩(3); 3,4-二氟溴苯与3反应得到2-甲基-3-溴-5-(3,4-二氟苯基)噻吩(4); 在-78 ℃下全氟环戊烯与4反应, 得到一种新的二芳基乙烯类光致变色化合物1,2-双[2-甲基-5-(3,4-二氟苯基)噻吩-3-基]全氟环戊烯(DT-1). 用IR, NMR, MS和元素分析确定了化合物DT-1的结构, 并对该化合物的光致变色特性进行了初步研究. 相似文献
16.
S. V. Makarenko K. S. Kovalenko V. M. Berestovitskaya M. M. Zobacheva 《Russian Journal of General Chemistry》2013,83(9):1744-1750
The interaction of alkyl 2,3-dibromo-3-nitroacrylates with aroylhydrazines at room temperature or with 2,4-dinitrophenylhydrazine under reflux gives the corresponding 2-aroyl(aryl)hydrazono-3-bromo-3-nitropropanoates. Refluxing of ethyl 2,3-dibromo-3-nitroacrylate with a fourfold excess of benzoylhydrazine results in ethyl-2,3-bis(benzoylhydrazono)propanoate. The structure of compounds obtained has been proved by IR, 1H NMR, 13C-{1H} NMR, and electron spectroscopy methods. 相似文献
17.
Weber L Werner V Domke I Stammler HG Neumann B 《Dalton transactions (Cambridge, England : 2003)》2006,(31):3777-3784
Reaction of 2-bromo-1,3-diethyl-1,3,2-benzodiazaborole (1) with equimolar amounts of thienyl lithium or 2,2-dithienyl lithium led to the generation of benzodiazaboroles 2 and 3 which are functionalized at the boron atom by a 2-thienyl or a 5-(2,2-dithienyl) unit. Similarly 2-bromo-1,3-diethyl-1,3,2-naphthodiazaborole (4) and thienyl lithium or 2,2-dithienyl lithium afforded the naphthoborolyl-substituted thiophene 5 or dithiophene 6. Treatment of 2,5-bis(dibromoboryl)-thiophene 7 with 2 eq. of tBuN=CH-CH=NtBu in n-hexane followed by sodium amalgam reduction of the obtained bis(diazaborolium) salt 8 gave the 2,5-bis(diazaborolyl)thiophene 9. The 2,5-bis(diazaborolidinyl)-thiophene 10 resulted from the cyclocondensation of 7 with 2 eq. of N,N-di-tert-butylethylenediamine in the presence of NEt3. Analogously, cyclocondensation of 7 with N,N-diethylphenylenediamine gave the bis(benzodiazaborolyl) functionalized thiophene 11. The novel compounds were characterized by elemental analysis and spectroscopy (1H-, 11B-, 13C-NMR, MS and UV-VIS). The molecular structure of 3 was elucidated by X-ray diffraction. Cyclovoltammograms show an irreversible oxidation wave at 298-598 vs. Fc/Fc+. The borolylated thiophenes and dithienyls show intense blue luminescence with Stokes shifts of 30-107 nm. 相似文献
18.
G. P. Gromova L. I. Belen'kii M. M. Krayushkin 《Chemistry of Heterocyclic Compounds》1993,29(8):889-891
The electrophilic trichloromethylation of 3-chloro-, 3-bromo-, and 3,4-dibromothiophene was studied. It is shown that reaction is directed towards position 2, accompanied by frequent formation of the corresponding substituted di-(2-thienyl)dichloromethane. Trichloromethylation of -bromothiophenes is complicated by exchange of chlorine for bromine under the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1046–1048, August, 1993. 相似文献
19.
20.
Esteves AP Goken DM Klein LJ Lemos MA Medeiros MJ Peters DG 《The Journal of organic chemistry》2003,68(3):1024-1029
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate and characterize the reductive intramolecular cyclization of ethyl 2-bromo-3-(3',4'-dimethoxyphenyl)-3-(propargyloxy)propanoate (1) promoted by (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)nickel(I), [Ni(tmc)](+), electrogenerated at glassy carbon cathodes in dimethylformamide containing tetraalkylammonium salts. Cyclic voltammograms for reduction of [Ni(tmc)](2+) in the presence of 1 reveal that [Ni(tmc)](+) catalytically reduces 1 at potentials more positive than those required for direct reduction of 1. During controlled-potential electrolyses of solutions containing [Ni(tmc)](2+) and 1, catalytic reduction of the latter proceeds via one-electron cleavage of the carbon-bromine bond to form a radical intermediate that undergoes cyclization to afford 2-(3',4'-dimethoxyphenyl)-3-(ethoxycarbonyl)-4-methylenetetrahydrofuran (2). In the presence of a base (either electrogenerated or deliberately added as potassium tert-butoxide), 2 rearranges to give 2-(3',4'-dimethoxyphenyl)-3-(ethoxycarbonyl)-4-methyl-2,5-dihydrofuran (3). A mechanistic scheme is proposed to explain the results obtained by means of cyclic voltammetry and controlled-potential electrolysis. 相似文献