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1.
L. A. Es'kova E. S. Domnina G. G. Skvortsova V. K. Voronov N. N. Chipanina N. A. Kazakova 《Chemistry of Heterocyclic Compounds》1978,14(7):774-776
In addition to the principal reaction pathway — addition of bromine to the double bond of the vinyl group — in the bromination of 1-vinylpyrazoles, the hydrogen atom in the 4 position of the pyrazole ring undergoes substitution, and the liberated hydrogen bromide coordinates with the pyrazoles present in the reaction mixture.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 960–962, July, 1978. 相似文献
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Şimşek Nermin Arici Cengiz McKee Michael L. Ülkü Dinçcer Balci Metin 《Structural chemistry》2001,12(3-4):305-311
The electrophilic addition of bromine to dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate 10 at 0 and –60°C led in high yield to the formation of dibromide 11. However, high-temperature bromination of 10 in carbon tetrachloride at 77°C gave four products 12–15, three of them with nonrearranged skeleton. Similarly, bromination of the dibromides 14 and 15 at 77°C yielded the nonrearranged tetrabromides 13 and 16, respectively. The structure of the tetrabromide 13 was solved by single-crystal X-ray analysis. The formation mechanism is discussed and supported by calculations. 相似文献
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N. P. Shusherina T. I. Likhomanova S. N. Nikolaeva 《Chemistry of Heterocyclic Compounds》1982,18(12):1284-1286
The corresponding monobromides were obtained in the bromination of 1-alkyl-2-pyridones with bonded bromine (with N-bromosuccinimide and dioxane dibromide). The conditions under which the yields of the mixtures of isomers were 60–80%, and almost no dibromides were obtained, were found. It was established that the ratios of the 3- and 5-bromo isomers depend on the character of the brominating agent.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1662–1664, December, 1982. 相似文献
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Bromination of 3-(2-aminophenyl)sydnone 2 under a variety of conditions is reported. The products obtained are interrelated by a series of subsequent reactions. One major product is the bromoaryl compound 8, the first example of bromination on the aryl rather than sydnone ring when the two are in competition. Surprisingly, bromoaminosydnone 9, prepared from its nitro analogue, was not among the products obtained by direct bromination of 2. 相似文献
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É. Baum L. I. Belen'kii V. G. Kul'nevich T. E. Goldovskaya 《Chemistry of Heterocyclic Compounds》1982,18(5):499-502
Depending on the amount of bromine, the bromination of 1-(4-nitrophenyl)-2-formylpyrrole with bromine in chloroform without a catalyst gives 5-bromo and 4,5-dibromo derivatives. 4-Bromo-1-(4-nitrophenyl)-2-formylpyrrole is formed in the presence of excess AlC13, while a mixture of 3,4- and 4,5-dibromo derivatives with preponderance of the latter is formed with excess bromine. The results are compared with the literature data on the bromination of 2-formylpyrrole, 2-formylfuran, and 2-formylthiophene and are interpreted with allowance for the electronacceptor effect of the p-nitrophenyl substituent attached to the nitrogen atom of the pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 662–665, May, 1982. 相似文献
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Kenneth Turnbull Thomas L. Blackburn Daniel T. Esterline 《Journal of heterocyclic chemistry》1990,27(5):1259-1263
Bromination of the sydnone ring of several ortho-substituted N-arylsydnones is reported. Subsequent side-chain modification generally can be achieved without concomitant removal of the 4-bromo protective group. 相似文献
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The title ion reacts in 1:1 DF-SbF(5) and exchanges up to five protium atoms with deuterium. The incorporation of label was measured by GC-MS analysis of the methyl crotonate formed by methanol quenching. The isotopomer distribution at about 60% conversion, which shows a minimum for the d(1) and a maximum for the d(4) species, indicates that the intermediate dication with the second charge at C(3) loses a proton faster from C(4) than from C(2). Formation of the pentadeuteriocrotonyl cation indicates that the 1,4-dication (acyl primary alkyl) or the 1,2-dication must intervene in the process. Computer modeling of the kinetics for the multiple exchange process to fit the experimental deuterium distribution allowed determination of the relative rate constants and isotope effects (KIEs) for the formation of the carbocations from alkenoyl cations (beta-secondary KIE) and elimination from carbodications to alkenoyl cations (primary KIE). An exceptionally large beta-secondary KIE of ca. 2.0/hydrogen was found for the formation of the dication. A small primary isotope effect of ca. 1.5 was found for elimination from the dications to the alkenoyl cations. Elimination from the 1,3-acylalkyl dication to form the nonconjugated 3-butenoyl cation is 6-7 times faster than elimination to the conjugated 2-butenoyl cation. The rate ratio for the conversion of 3-butenoyl cation to the 1,4-dication (primary alkyl cation) and 1,3-dication (secondary alkyl cation) is (0.025-0.030):1, whereas the relative rate of the formation of the 1,2-acylalkyl dication (the alternative route of achieving pentadeuteration) is zero. 相似文献
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D. E. Chumakov A. V. Khoroshutin A. V. Anisimov K. I. Kobrakov 《Chemistry of Heterocyclic Compounds》2009,45(3):259-283
Methods for the bromination of porphyrins and their derivatives at the meso and β-positions are examined. The dependence of the course of the reactions on the conditions and on the structure of the
initial compounds is discussed.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 323-353, March, 2009. 相似文献
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Proton translocation along ammonia wires is investigated in 7-hydroxyquinoline.(NH(3))(n) clusters, both experimentally by laser spectroscopy and theoretically by Hartree-Fock and density functional (DFT) calculations. These clusters serve as realistic finite-size models for proton transfer along a chain of hydrogen-bonded solvent molecules. In the enol tautomer of 7-hydroxyquinoline (7-HQ), the OH group acts as a proton injection site into the (NH(3))(n)cluster. Proton translocation along a chain of three NH(3) molecules within the cluster can take place, followed by reprotonation of 7-HQ at the quinolinic N atom, forming the 7-ketoquinoline tautomer. Exoergic proton transfer from the OH group of 7-HQ to the closest NH(3) molecule within the cluster giving a zwitterion 7-HQ-.(NH(3))(6)H+ (denoted PT-A) occurs at a threshold cluster size of n = 6 in the DFT calculations and at n = 5 or 6 experimentally. Three further locally stable zwitterion clusters denoted PT-B, PT-B', and PT-C, the keto tautomer, and several transition structures along the proton translocation path were characterized theoretically. Grotthus-type proton-hopping mechanisms occur for three of the proton transfer steps, which have low barriers and are exoergic or weakly endoergic. The step with the highest barrier involves a complex proton transfer mechanism, involving structural reorganization and large-scale diffusive motions of the cluster. 相似文献
14.
A. N. Grinev I. A. Kharizomenova M. V. Kapustina Yu. N. Sheinker L. M. Alekseeva N. M. Rubtsov 《Chemistry of Heterocyclic Compounds》1987,23(4):384-386
Bromination of 2-acylamino-3-ethoxycarbonyl-7-oxo-4,5,6,7-tetrahydrobenzo[b]-thiophenes has been studied. This reaction affords 2-acylamino-6,6-dibromo-3-ethoxycarbonyl-7-oxo-4,5,6,7-tetrahydrobenzo[b]thiophene, which on dehydrobro-mination gives 6-bromo-7-oxybenzo[b]thiophene derivatives. The 4,6-dibromo- and 4,6-dinitro-7-oxybenzo[b]thiophenes were also obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 460–462, April, 1987. 相似文献
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The high-temperature bromination of 1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalene and its carboethoxy derivative was studied. Reaction of the title compound with 1 mol of bromine in refluxing carbon tetrachloride resulted in the formation of ring-opening products. In the case of the carboethoxy derivative, bromination took place both regio- and stereospecifically at the benzylic positions, the cyclopropane ring did not undergo bond cleavage. A mechanism for the formation of the products and their dehydrobromination reactions is discussed. 相似文献
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Naphthalenes bearing an acyl and a phenyl group in a peri relationship give rise to a pair of enantiomers in the temperature range where the rotations of the acyl group are slow. Such enantiomers were observed by means of low temperature NMR spectra in chiral environments. The barrier to rotation for the acyl substituents, that causes the interconversion of the enantiomers, was demonstrated to be lower than that for the phenyl group. In an appropriately synthesized derivative it was possible to measure the two barriers that were found equal to 10.4 and 15.9 kcal mol(-)(1), respectively. The barriers for the acyl group rotation increase regularly (from 9.5 to 13.2 kcal mol(-)(1)) with the increasing dimension of the RCO groups (R = Me, Et, Pr(i), Bu(t)). When a bromine atom replaces the phenyl group, the enantiomerization barrier for the corresponding acyl derivatives increases significantly. 相似文献
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Froelich O Desos P Bonin M Quirion JC Husson HP Zhu J 《The Journal of organic chemistry》1996,61(19):6700-6705
The asymmetric synthesis of a series of 2-(1-aminoalkyl) piperidines using (-)-2-cyano-6-phenyloxazolopiperidine 1 is described. LiAlH(4) reduction of 1 followed by hydrogenolysis led to the diamine 3. The same strategy applied to C-2-methylated compound 7 afforded [(2S)-2-methylpiperidin-2-yl]methanamine (9). Addition of lithium derivatives to the cyano group of 1 resulted in the formation of an intermediate imino bicyclic system (11a-c) which could be diastereoselectively reduced to substituted diamino alcohols 13a-c. The addition of an excess of PhLi to 1 in the presence of LiBr furnished disubstituted amine 19, the precursor of diphenyl[(2S)-piperidin-2-yl]methanamine (22). 相似文献
20.
The low and high temperature bromination reactions of bromobenzonorbornadiene derivatives were studied and the possible role of a neighboring group in rearrangements was investigated. New polybrominated benzonorbornadiene and benzonorbornene derivatives were synthesized. All compounds were characterized properly using NMR spectroscopy. 相似文献