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171.
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Viacheslav A. Petrov Frederic Davidson Alexander A. Marchione 《Journal of fluorine chemistry》2005,126(4):599-608
Reaction of quadricyclane (1) with fluoroolefins of different structure results in stereoselective formation of polyfluorinated exo-tricyclo[4.2.1.02,5]non-7-enes. The reaction of a mixture of trans/cis CF3CFCFCF3 with 1 is stereoselective and the resulting cycloadducts 7a, b preserve the original alkene stereochemistry. The relative rate constants of cycloaddition of a series of fluoroolefins to 1 under pseudo first-order conditions measured by kinetic NMR at 109 °C provide a kinetic scale of reactivities of the fluoroolefins in this reaction.These relative rate constants correlate well with the number of fluoroalkyl groups connected to the double bond, reaching a maximum for the tri-substituted olefin: CF3CFCF2:CF3CFCFCF3:(CF3)2CC(CF3)2:(CF3)2CCFC2F5 = 1:1.2-1.9:4:138. 相似文献
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The EPR magic angle linewidth and dynamic shift have been measured as a function of frequency in TMMC. Both the linewidth and the shift vary with frequency as . These results support strongly the one-dimensional behaviour of the relaxation dynamics of this compound. The results are in good agreement with a recent calculation. 相似文献
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We introduce some new techniques into superfield perturbation theory which allow considerable simplifications in calculations. As a result, we show that all contributions to the effective action can be written as integrals over a single d4θ. We also give the background group field formalism for supersymmetric non-abelian gauge theories. To illustrate our methods, we give examples of loop calculations: in particular, we show that in O(4) extended supersymmetric non-abelian gauge theories all one-loop propagator corrections cancel identically (both infinite and finite parts) and that these theories, at one loop, are finite and have no renormalizations (in the Fermi-Feynman gauge). 相似文献
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The intramolecular iodo-aldol cyclization of alpha-substituted enoate aldehydes and ketones is described. Using prochiral starting materials, the reaction produces hetero- and carbocycles containing quaternary centers adjacent to secondary or tertiary centers. The reactions occur in good yields and are highly selective for the trans-products, having the hydroxyl and iodomethyl groups on opposite faces of the ring system. 相似文献