A study of the dual electrophilic and pericyclic reactivity of 4,6-dinitrobenzofurazan (DNBZ, 2), 4,6-dinitro-2,1,3-benzothiadiazole (DNBS, 3), 4,6-dinitro-2,1,3-benzoselenadiazole (DNBSe, 4) is reported. Kinetic and thermodynamic measurements of the ease of covalent hydration of 2-4 to give the corresponding hydroxy sigma-adducts C-2-C-4 have been carried out over a large pH range in aqueous solution
Mayr electrophilicity predicts the dual Diels–Alder and σ-adduct formation behaviour of heteroaromatic super-electrophiles
作者:Sami Lakhdar、Régis Goumont、François Terrier、Taoufik Boubaker、Julian M. Dust、Erwin Buncel
DOI:10.1039/b702060k
日期:——
Diels-Alder (normal and inverse electron demand) reactivity of this series of heteroaromatic electrophiles and have shown that Mayr E values are valid predictors of whether DA adducts will form and how rapidly. The observed order of pericyclic reactivity corresponds to E = -8.5 as the demarcation E value, in close agreement with sigma complexation; thus pointing to a common origin for the two processes, i.e
Synthesis of novel polycyclic heterosystems from 5-nitro[1,2,5]selenadiazolo[3,4-e]benzofuroxans
作者:Maxim A. Bastrakov、Alexey M. Starosotnikov、Alexander A. Pavlov、Igor L. Dalinger、Svyatoslav A. Shevelev
DOI:10.1007/s10593-016-1950-3
日期:2016.9
the preparation of 5-nitro[1,2,5]selenadiazolo[3,4-e]benzofuroxan has been developed. Employing the reactivity of this compound in pericyclic (4+2) and (3+2) cycloaddition reactions as a dienophile or dipolarophile (at the C=C–NO2 bond) with a heterodiene (fragment C=C–N(O)=O) representatives of novel types of fused polycyclic heterosystems were synthesized.
Synthesis of stable adducts of highly electrophilic nitro(het)arenes with С-nucleophiles
作者:A. M. Starosotnikov、M. A. Bastrakov、V. A. Kokorekin
DOI:10.1007/s11172-022-3435-0
日期:2022.3
The reaction of highly electrophilic azolo[b]pyridines with pyrrole and indole derivatives as nucleophiles afforded 1,4-addition products to the pyridine ring. The reactions of structurally similar meta-dinitrobenzo-fused heterocycles (furoxan, thiadiazole, selenadiazole, pyridine) with C-nucleophiles (salts of ketones and 2-nitropropane) gave stable anionic σ-complexes in high yields. Their oxidation led to rearomatization with the formation of the corresponding products of substitution of a hydrogen atom with the nucleophile. The oxidation was generally accompanied by the decomposition of σ-complexes into the parent compounds.
A criterion to demarcate the dual Diels–Alder and σ-complex behaviour of aromatic and heteroaromatic superelectrophiles
作者:R. Goumont、F. Terrier、D. Vichard、S. Lakhdar、Julian M. Dust、E. Buncel
DOI:10.1016/j.tetlet.2005.09.159
日期:2005.11
A frontier demarcating superelectrophilic compounds that undergo both Diels-Alder reactivity and sigma-complexation reactions, from traditional electrophiles, is afforded through the thermodynamic tendency for sigma-complexation as defined by the pK(a) values for H2O addition to electron-deficient aromatic and heteroaromatic substrates. (c) 2005 Elsevier Ltd. All rights reserved.