共查询到20条相似文献,搜索用时 17 毫秒
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Jie Zhang Shengyu Feng Dacheng Feng Ju Xie 《International journal of quantum chemistry》2005,105(1):57-65
The 1,2‐rearrangements in silylmethanethiol were studied by ab initio molecular orbital theory. The structures of reactants, transition states, and products were fully optimized at the MP2(full)/6‐31G(d) levels. Based on the MP2(full)/6‐31G(d) geometries, harmonic frequencies were obtained. Energies were computed at the G3 level of theory with MP2(full)/6‐31G(d) zero‐point corrections. The results indicate that the 1,2‐rearrangement in silylmethanethiol may occur via two pathways. Pathway A involves the 1,2‐migration of mercapto group from carbon to silicon via a double three‐membered ring transition state, forming methylsilanethiol. The barrier for reaction A is 275.0 kJ/mol. Pathway B involves the 1,2‐migration of silyl group from carbon to sulfur via a four‐membered ring transition state, forming methylthiosilane. The barrier for reaction B is 262.3 kJ/mol. Thermodynamic and kinetic properties of the reactions were analyzed over a temperature range of 300–1,300K. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
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The hydroxylation of 1-alkyl-3-(2-quinolyl)quinolinium halides by an alkaline solution of K3[Fe(CN)6] in aqueous 1,4-dioxane leads to a mixture of 1-alkyl-3-(2-quinolyl)-1,2-dihydro-2-quinolones and 1-alkyl-3-(2-quinolyl)-1,4-dihydro-4-quinolones with predominance of the former. The use of the system of K3[Fe(CN)6]/Mg(OH)2 in aqueous 1,4-dioxane leads to the regiospecific formation of 1-alkyl-3-(2-quinolyl)-1,4-dihydro-4-quinolones. 相似文献
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1-X-1-Oxo-1,2-dihydro-4H-3,1-benzoxaphosphorins (X = CH2Cl, Ph, and OH) were obtained by reacting ortho-(butoxymethoxymethyl)phenylmagnesium bromide with derivatives of chloromethylphosphonic and chloromethylphosphinic acids, followed by intramolecular alkylation. X-Ray diffraction was used to study the molecular and crystalline structure of one of these compounds (with X = OH).Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2174–2180, September, 1992. 相似文献
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I. A. Aitov V. N. Nesterov Yu. A. Sharanin Yu. T. Strachkov 《Russian Chemical Bulletin》1996,45(2):417-419
The reaction of (4-R-benzoyl)(2-bromopyridinitim) methylides with ethoxyrnethylene-rnalononitrile is stereoselective and affords Z-1-[1-(4-R-benzoyl)-2-ethoxyvinyl]-2-dicyationietliylene-1,2-dihydropyridines. The structure of 1-[1-(4-chlorobenzoyl)-2 ethoxyvinyll-2-dicyanomethylene-1,2-dihydropyridine has been established by X-ray structural study.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 434–436, February, 1996. 相似文献
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The kinetics of the degenerate rearrangement of 1-methoxy-1,2-dimethylacenaphthylenonium ion in superacidic media with varying acidity were studied by the dynamic1H NMR method. It was concluded that the inhibiting effect of the acidic medium on the migration of the OR groups in the -OR-substituted carbocations was due not only to protonation of these groups but also to their specific solvation (the formation of hydrogen bonds with the molecules of the medium). Energy estimates of the effect were made for the cases where R=Me and H.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1315–1322, June, 1992. 相似文献
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N. M. Karimova Yu. L. Teplenicheva A. F. Kolomiets A. V. Fokin 《Russian Chemical Bulletin》1997,46(6):1136-1139
The basicity of 1-alkyl-2-trifluoromethylaziridines is-two orders of magnitude lower than that of non-fluorinated analogs.
Aziridines are stable to H2S and AcOH, but react with AcSH, HCl, HBr, H2SO4, TsOH, and picric acid to give products of ring-opening.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1185–1188 June, 1997. 相似文献
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The action of lithium butyl acetylenide in THF causes 4,4-diethyl-1,2-dithiolane to undergo ring-opening to form 2,2-diethyl-4-thia-5-decyne-1-thiol,
which cyclizes to give 2-butyl-6,6-diethyl-5,6-dihydro-1,4-dithiepin by either a homolytic or a nucleophilic mechanism.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 204–206, January, 1997. 相似文献
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E. I. Klimova T. Klimova Berestneva J. M. Martínez Mendoza J. M. Méndez Stivalet R. A. Toscano M. Martínez García 《合成通讯》2013,43(14):2299-2315
2-Ferrocenylmethylidene-1,2-diphenylpropanedione (3), 2,4-dibenzoyl-3-ferrocenyl-1,5-diphenylpentane-1,5-dione (4), and 2,4-dibenzoyl-3-ferrocenyl-2-[(ferrocenyl)hydroxymethyl]-1,5-diphenylpentane-1,5-dione (5) react with MeLi to undergo fragmentation and 1,2-addition or only 1,2-addition at the carbonyl group. Dehydration of intermediate tertiary alcohols affords α-methylstyrene (6), 3-ferrocenyl-1-phenylprop-2-enone (7), 3,5-diferrocenyl-1-phenyl-4-(1-phenylvinyl)cyclohexene (8), 3-ferrocenylmethylidene-2,4-diphenylpenta-1,4-diene (9), 2-benzoyl-1-ferrocenyl-3-phenylbuta-1,3-diene (10), 2-benzoyl-1-ferrocenyl-3-methylindene (11), 4-ferrocenyl-2-methyl-2,6-diphenyl-3,4-dihydro-2H-pyran (19), and (Z,Z)-2,4-dibenzoyl-1,3-diferrocenyl-5-phenylhexa-1,4-diene (21), isolated by chromatography. The spatial structures of ferrocenyldihydropyran (19) and diferrocenylhexadiene (21) were established by X-ray diffraction analysis. 相似文献
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Fillmore Freeman Choonsun Lee Henry N. Po Warren J. Hehre 《Journal of computational chemistry》1998,19(9):1064-1071
Optimized geometries and energies for 3,4-dihydro-1,2-dithiin ( 1 ), 3,6-dihydro-1,2-dithiin ( 2 ), 4H-1,3-dithiin ( 3 ), and 2,3-dihydro-1,4-dithiin ( 4 ) were calculated using ab initio 6-31G* and MP2/6-31G*//6-31G* methods. At the MP2/6-31G*//6-31G* level, the half-chair conformer of 4 is more stable than those of 1 , 2 , and 3 by 2.5, 3.5, and 3.6 kcal/mol, respectively. The half-chair conformers of 1 , 2 , 3 , and 4 are 2.9, 7.1, 2.0, and 5.6 kcal/mol, respectively, more stable than their boat conformers. The calculated half-chair structures of 1 – 4 are compared with the calculated chair conformer of cyclohexane and the half-chair structures for cyclohexene, 3,4-dihydro-1,2-dioxin ( 5 ), 3,6-dihydro-1,2-dioxin ( 6 ), 4H-1,3-dioxin ( 7 ), and 2,3-dihydro-1,4-dioxin ( 8 ). © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1064–1071, 1998 相似文献
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Vadim A. Soloshonok Hironari Ohkura Manabu Yasumoto 《Journal of fluorine chemistry》2006,127(6):708-711
The reaction of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione with (R)-phenylglycinol was found to proceed via intermediate formation of (R, 4E, 6Z)-5,7-bis-(trifluoromethyl)-2,3-dihydro-3-phenyl-1,4-oxazepine which further underwent a base-catalyzed 1,3-proton shift reaction followed by [1,2] Wittig rearrangement giving rise to 2,4-bis-(trifluoromethyl)-6-phenylpyridine. 相似文献
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LI Ting-you JIANG Shui-shi WANG Zong-mu 《高等学校化学研究》2005,21(6):761-762
There is a classic experiential rule about 1,2-diol RCR^1 (OH) CR^1 (OH) R( R^1 = H or methyl), that is, the proton chemical shift of the α-R^1 group at the hydroxvl group in the all-isomer, in general, aPPears in a higher field with ca. 相似文献
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Matteo AdinolfiAlfonso Iadonisi Alessandra RavidàMarialuisa Schiattarella 《Tetrahedron letters》2003,44(43):7863-7866
Peracetylated sugars can be efficiently converted into the corresponding 1,2-ethylidenes, -orthoesters, and -glycals via the in situ generation of glycosyl iodides promoted by I2/Et3SiH. The approach is straightforward and avoids isolation of the sensitive iodinated intermediates. 相似文献
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Mamedov V. A. Kalinin A. A. Gubaidullin A. T. Chernova A. V. Litvinov I. A. Levin Ya. A. Shagidullin R. R. 《Russian Chemical Bulletin》2004,53(1):164-175
The reactions of 3-benzoylquinoxalin-2-one and its N(1)-alkyl derivatives with 1,2-phenylenediamines were accompanied by ring contraction as a result of the quinoxaline-benzoimidazole rearrangement giving rise to 2-benzoimidazolyl-substituted quinoxalines. The possible pathways of these reaction are discussed. 相似文献
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Dzmitry G. Kananovich 《Tetrahedron letters》2007,48(48):8424-8429
Methanesulfonates of readily available cis-1,2-disubstituted cyclopropanols on reaction with magnesium bromide in diethyl ether undergo cyclopropyl-allyl rearrangement to afford allyl bromides, with an (E)-trisubstituted double bond, as main products. The amount of the corresponding (Z)-isomers did not exceed 5% when the reaction was performed at 0 °C, and the major concomitant products were the regioisomeric secondary bromides. The latter are sufficiently less reactive towards sulfur, phosphorus and hydrogen nucleophiles than the dominant (E)-disubstituted allyl bromides and these reactions are suitable for the stereoselective preparation of trisubstituted olefins. 相似文献