- Effects of photophysical properties of 1,4-cyclohexadiene derivatives on their [2 + 2] photocycloaddition reactivities: Experimental and theoretical studies
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To study the relationship between the [2 + 2] photocycloaddition reactivities of 1,4-cyclohexadiene derivatives (1,4?CHDs) and their structures, photophysical properties of a series of 1,4?CHDs were studied experimentally and by performing theoretical calculations. Specifically, UV–vis absorption spectra of these compounds in diluted solutions were acquired and the theoretical calculations were performed at the density functional theory (DFT) level. Their UV–vis absorption maxima were found to be related to the substituents on the 1,4-cyclohexadiene ring. To describe the [2 + 2] photocycloaddition reactivities of the 1,4?CHDs, time-dependent density functional theory (TDDFT) was used to optimize their ground- and excited-state structures, and their electronic excitation energies were calculated at the M062X/def-TZVP level. Frontier molecular orbitals and electron-hole distribution analyses were used to illustrate the electron transition modes of the 1,4?CHDs. The differences between the ground- and excited-state structures of the different 1,4?CHDs were characterized by carrying out a root-mean-square-deviation (RMSD) analysis. The results showed that the photophysical properties of 1,4?CHDs are meaningful for explaining their [2 + 2] photocycloaddition reactivities.
- Zhang, Xiaokun,Cui, Jingrui,Yan, Hong
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- PYRIDAZINONE-BASED BROAD SPECTRUM ANTI-INFLUENZA INHIBITORS
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The present invention relates to compounds of formula (I): (I) or pharmaceutically acceptable salts thereof, as well as processes for their manufacture, pharmaceutical compositions comprising them, and their use as medicaments.
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Page/Page column 91
(2018/02/28)
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- Small Rings, 42. Attempts to Prepare Oxirenes via Photochemical Cycloreversions
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Photochemically induced cycloreversions, which are ideally suited for the matrix isolation of cyclobutadienes, cannot be used for an analogous preparation and identification of oxirenes.In some cases ketenes are formed instead.
- Maier, Guenther,Sayrac, Tugmac,Reisenauer, Hans Peter
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p. 2202 - 2213
(2007/10/02)
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- Alkynes and Cumulenes, XII. The Application of Di-tert-butyl Acetylenedicarboxylate in Diels-Alder Additions
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Di-tert-butyl acetylenedicarboxylate (1) may be added in good yields to the model dienes 1,3-butadiene (6a), 2-methyl-1,3-butadiene (6b), 2,3-dimethyl-1,3-butadiene (6c), furan (10), and 1,3-cyclohexadiene (19) to afford the Diels-Alder adducts 7a-c, 12 (E = CO2C(CH3)3), and 20, respectively.Under certain conditions the reaction with 10 also laeds to the four 2:1-adducts 13-16 (E = CO2C(CH3)3).Whereas the esters 7a-c are converted in quantitative yields to the corresponding anhydrides 8a-c by warming in the presence of catalytic amounts of p-toluenesulfonic acid or by heating in substance, the decomposition of 12 and 20 stops at the stage of the monoesters 17 and 21, respectively.Competition experiments show that 1 is approximately three times less reactive towards 6c than dimethyl acetylenedicarboxylate (11).It is shown that 1 is a useful dienophile for the preparation of "mixed" paracyclophanes of type 28.
- Weber, Gisela,Menke, Klaus,Hopf, Henning
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p. 531 - 541
(2007/10/02)
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- Antimicrobial composition and method containing N-(3,5-dihalophenyl)-imide compounds
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Novel N-(3,5-dihalophenyl)imide compounds, which exhibit a strong antimicrobial activity against microorganisms including phytopathogenic fungi, parasites of industrial products and pathogenic microorganisms, represented by the formula, STR1 wherein X and X' each represent halogens and A represents a substituted ethylene such as chloroethylene, C1 - C4 alkylthioethylene, C1 - C2 alkyl-ethylene or 1,2-di-C1 - C2 -alkyl-ethylene, a cyclopropylene such as 1,3-dimethylcyclopropylene, trimethylene, a cyclohexylene-1,2-, cyclohexenylene-1,2-, cyclohexadienylene-1,2- or o-phenylene. The N-(3,5-dihalophenyl)imide compounds can be obtained by any of methods which produce imide compounds or reaction of an N-(3,5-dihalophenyl)maleimide compound with a mercaptan, a hydrogen halide, phosphorus chloride or thionylchloride.
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