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Benzonitrile Oxide (benzonitrile + oxide)
Selected AbstractsDFT-HSAB Prediction of Regioselectivity in 1,3-Dipolar Cycloadditions: Behavior of (4-Substituted)benzonitrile Oxides towards Methyl Propiolate,CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2006Alessandro Ponti Dr. Abstract The regioselectivity of 1,3-dipolar cycloadditions between (4-substituted)benzonitrile oxides and methyl propiolate cannot be rationalized on the basis of the electron demand of the reactants or frontier molecular-orbital theory. To this problem, we have applied a quantitative formulation of the hard,soft acid,base principle developed within the density functional theory. Global and local reactivity indices were computed at B3LYP/6-311+G(d,p) level. The details of charge transfer upon the reactive encounter have been elucidated, and the computed regioselectivity has been shown to be in good agreement with experimental data. [source] A Straightforward Synthesis of Isoxazoline-Based Carbocyclic Nucleosides from 1,3-Cyclohexadiene through Nitrosocarbonyl ChemistryEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2007Paolo Quadrelli Abstract 3-Benzoyl-2-oxa-3-azabicyclo[2.2.2]oct-5-ene undergoes cycloaddition with benzonitrile oxide to afford a mixture of syn and anti regioisomeric cycloadducts. The anti cycloadducts were easily elaborated to stereodefined isoxazoline-based carbocyclic aminols that serve as synthons for the linear construction of purine nucleosides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Cycloadditions in mixed aqueous solvents: the role of the water concentration,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2005Theo Rispens Abstract We examined the kinetics of a series of cycloaddition reactions in mixtures of water with methanol, acetonitrile and poly(ethylene glycol) (MW 1000). The reactions include the Diels,Alder (DA) reaction between cyclopentadiene and N - n -butylmaleimide or acridizinium bromide, the retro-Diels-Alder (RDA) reaction of 1,4,4a,9a-tetrahydro-4a-methyl-(1,,4,,4a,,9a,)-1,4-methaneanthracene-9,10-dione and the 1,3-dipolar cycloaddition of benzonitrile oxide with N - n -butylmaleimide. Plots of logk vs the molar concentration or volume fraction of water are approximately linear, but with a characteristic break around 40,M water. This break, absent for the RDA reaction, is ascribed to hydrophobic effects. Comparison with aqueous mixtures of the more hydrophobic 1-propanol shows that these mixtures induce qualitatively similar effects on the rate, but that preferential solvation effects cause the mixtures of 1-propanol to exhibit a more complex behavior of logk on composition. The results are analyzed using the Abraham,Kamlett,Taft model. The solvent effects in aqueous mixtures are not satisfactorily described by this model. For some cycloadditions, small maxima in rate are observed in highly aqueous mixtures of alcohols. The origin of these maxima and the aforementioned breaks is most likely the same. Copyright © 2005 John Wiley & Sons, Ltd. [source] DFT-HSAB Prediction of Regioselectivity in 1,3-Dipolar Cycloadditions: Behavior of (4-Substituted)benzonitrile Oxides towards Methyl Propiolate,CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2006Alessandro Ponti Dr. Abstract The regioselectivity of 1,3-dipolar cycloadditions between (4-substituted)benzonitrile oxides and methyl propiolate cannot be rationalized on the basis of the electron demand of the reactants or frontier molecular-orbital theory. To this problem, we have applied a quantitative formulation of the hard,soft acid,base principle developed within the density functional theory. Global and local reactivity indices were computed at B3LYP/6-311+G(d,p) level. The details of charge transfer upon the reactive encounter have been elucidated, and the computed regioselectivity has been shown to be in good agreement with experimental data. [source] | ||||||||||