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Selectivity Descriptors for the Michael Addition Reaction as Obtained from Density Functional Based Approaches
Ist Teil von
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 2005-01, Vol.109 (2), p.387-393
Ort / Verlag
United States: American Chemical Society
Erscheinungsjahr
2005
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Density functional (DF) based numerical approaches for computing orbital and atomic reactivity indices were employed in the study of selectivity descriptors for the 1,4 Michael addition reaction. To this aim, atomic and orbital Fukui indices and atomic softnesses for 2-arylmethylene-1,4-butanolides and N,N-disubstituted phenylacetamides were computed. Further on, these local selectivity descriptors have been rationalized in terms of the Pearson's hard−soft-acid−base principle to explain the observed regioselectivity. It is shown that the methods employed for local (atomic and orbital) reactivity index computations are useful and reliable for prediction of the regioselectivity upon conjugate addition of ambident nucleophiles to 2,3-unsaturated carboxylic esters. All the results reveal similar degree of localization/hardness of the 1,4-butanolides C4 and active α-carbon belonging to the N,N-dimethyl-phenylacetamide, while the soft α-carbon in LiCH2CN reacts with the soft C2 1,4-butanolide center.