116271-00-2Relevant articles and documents
Reactions of nitroheteroarenes with carbanions: Bridging aromatic, heteroaromatic and vinylic electrophilicity
Seeliger, Florian,Blazej, Sylwia,Bernhardt, Sebastian,Makosza, Mieczyslaw,Mayr, Herbert
, p. 6108 - 6118 (2008)
The relative rate constants for the vicarious nucleophilic substitution (VNS) of the anion of chloromethyl phenyl sulfone (1-) with a variety of nitroheteroarenes, for example, nitropyridines, nitropyrroles, nitroimidazoles, 2-nitrothiophene, and 4-nitropyrazole, have been determined by competition experiments. It was shown that nitropyridines are approximately four orders of magnitude more reactive than nitrobenzene. Among the five-membered heterocycles 2-nitrothiophene is the most active followed by nitroimidazoles and 4-nitropyrazole. Nitropyrroles are the least electrophilic nitroheteroarenes with reactivities comparable to nitrobenzene. Quantum chemically calculated methyl anion affinities (B3LYP/6-311 G(d,p)//B3LYP/ 6-31G(d)) of the nitroarenes correlated only moderately with the partial relative rate constants. The correlation of these activities with the LUMO energies of nitroarenes is even worse. By measuring the second-order rate constants of the addition of 1" to nitroarenes and to diethyl arylidenemalonates 10, it was possible to link the electrophilic reactivities of nitroheteroarenes with the comprehensive electrophilicity scale based on the linear-free-energyrelationship log k(20°C) = s(N + E).
Vicarious Nucleophilic Substitution of Hydrogen in Imidazole Derivatives
Makosza, Mieczyslaw,Kwast, Ewa
, p. 287 - 292 (2007/10/02)
Nitroderivatives of imidazole react with carbanions containing leaving groups at the carbanion center yielding products of vicarious nucleophilic substitution of hydrogen at positions activated by the nitro group.Some aspects of the orientation pattern ar
