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The reaction of tellurium tetrachloride with acetylene in CCl4 at atmospheric pressure and ambient temperature affords earlier unknown (E)-2-chlorovinyltellurium trichloride in 30% yield, whose reduction with sodium bisulfite gives (E,E)-bis(2-chlorovinyl) ditelluride in 64% yield. 相似文献
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Leonid Breydo Charles L. Barnes Kent S. Gates 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o447-o449
In order to characterize the structural elements that might play a role in non-covalent DNA binding by the antitumor antibiotic leinamycin, we have solved the crystal structures of the two leinamycin analogs, methyl (R)-5-{2-[1-(tert-butoxycarbonylamino)ethyl]thiazol-4-yl}penta-(E,E)-2,4-dienoate, C16H22N2O4S, (II), and 2-methyl-8-oxa-16-thia-3,17-diazabicyclo[12.2.1]heptadeca-(Z,E)-1(17),10,12,14-tetraene-4,9-dione, C14H16N2O3S, (III). The penta-2,4-dienone moiety in both of these analogs adopts a conformation close to planarity, with the thiazole ring twisted out of the plane by 12.9 (2)° in (II) and by 21.4 (4)° in (III). 相似文献
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Insertion of elemental selenium or tellurium into the Csp2-Zr bond of alkenylchlorozirconocenes followed by oxidation in air affords (E)-divinyl diselenides or (E)-divinyl ditellurides. 相似文献
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(E)-Alkenylpentafluorosilicates react with copper(II) thiocyanate in DMF at ambient temperature to give (E)-alkenyl thiocyanates stereoselectively in high yields. 相似文献
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Issa Yavari Hassan Kabiri-Fard Shahram Moradi 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1459-1468
Summary. Ab initio calculations at the HF/6-31G* level of theory for geometry optimization and the MP2/6-31G*//HF/6-31G* level for a single point total energy calculation are reported for (Z,Z)-, (E,Z)-, and (E,E)-cycloocta-1,4-dienes. The C
2-symmetric twist-boat conformation of (Z,Z)-cycloocta-1,4-diene was calculated to be by 3.6 kJ·mol−1 more stable than the C
S-symmetric boat-chair form; the calculated energy barrier for ring inversion of the twist-boat conformation via the C
S-symmetric boat-boat geometry is 19.1 kJ·mol−1. Interconversion between twist-boat and boat-chair conformations takes place via a half-chair (C
1) transition state which is 43.5 kJ·mol−1 above the twist-boat form. The unsymmetrical twist-boat-chair conformation of (E,Z)-cycloocta-1,4-diene was calculated to be by 18.7 kJ·mol−1 more stable than the unsymmetrical boat-chair form. The calculated energy barrier for the interconversion of twist-boat-chair
and boat-chair is 69.5 kJ·mol−1, whereas the barrier for swiveling of the trans-double bond through the bridge is 172.6 kJ·mol−1. The C
S symmetric crown conformation of the parallel family of (E,E)-cycloocta-1,4-diene was calculated to be by 16.5 kJ·mol−1 more stable than the C
S-symmetric boat-chair form. Interconversion of crown and boat-chair takes place via a chair (C
S) transition state which is 37.2 kJ·mol−1 above the crown conformation. The axial- symmetrical twist geometry of the crossed family of (E,E)-cycloocta-1,4-diene is 5.9 kJ·mol−1 less stable than the crown conformation.
Corresponding author. E-mail: isayavar@yahoo.com
Received March 25, 2002; accepted April 3, 2002 相似文献
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Burchell CJ Kilian P Slawin AM Woollins JD Tersago K Van Alsenoy C Blockhuys F 《Inorganic chemistry》2006,45(2):710-716
A synthetic, spectroscopic, and theoretical study of Ex(CN)2 (E = S, Se; x = 1-3) is described. The X-ray structures of Se2(CN)2 and Se3(CN)2 have been determined. Se2(CN)2 crystallizes in a chiral space group with the CN groups approximately gauche. 相似文献
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Potassium alkoxides of N-acyloxazolidin-2-one derived syn-aldolates undergo a novel tandem intramolecular cyclisation elimination reaction to afford trisubstituted (E)-alpha,beta-unsaturated amides in high d.e., which may be converted into their corresponding acids or oxazolines in good yield. 相似文献
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symmetrical (E,E)-1,3-dienes can be prepared by high yields from (E)-alkenylpentafluorosilicates either by treating with silver fluoride in acetonitrile or by stirring with silver nitrate in water/ether. 相似文献
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A recently discovered radical fragmentation of 2-fluoro-6-pyridinoxy derivatives allows a new highly stereoselective and convergent route to (E)-vinylsulfones from allylic alcohols. Reductive desulfonylation or nickel-catalyzed couplings furnish di- and trisubstituted (E)- and (Z)-alkenes. 相似文献
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S. Gupta J. K. Ray K. Chinnakali H.-K. Fun 《Acta Crystallographica. Section C, Structural Chemistry》1999,55(2):IUC9900012-IUC9900012
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Conclusions The electrophilic cyclization of (E, E)-2-farnesylthiophene has been studied for the first time, and it has been shown that the allylic thienyl group acts as a specific terminator which leads to the formation of a tetra cyclic molecule with a cis-hydrindane fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1359–1362, June, 1981.Deceased. 相似文献