Regio- and stereoselectivity of polar [2+3] cycloaddition reactions between (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone and selected (E)-2-substituted nitroethenes

Abstract

Abstract[2+3] Cycloaddition reactions of the highly reactive (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone with (E)-2-R-nitroethenes proceed under mild conditions and yield mixtures of stereoisomeric 2-methyl-3-(3,4,5-trimethoxyphenyl)-4-nitro-5-R-isoxazolidines. The effect of regiospecificity of the cycloadditions may be accounted for by the theory of electrophilicity indexes. Stereoselectivity, however, is determined by a compilation of steric and secondary orbital effects.

Kinetic aspects of [3+2] cycloaddition reactions between (E)-3,3,3-trichloro-1-nitroprop-1-ene and ketonitrones

“…It can be concluded from the above that not steric, but electronic factors have the decisive influence on the course of these reactions. Nitroethene has a significantly less strongly shielded C=C bond, but at the same time it has clearly lower global electrophilicity (x = 2.61 eV [17], in comparison to 3.43 eV in case of E-3,3,3-trichloro-1-nitroprop-1-ene [14] ).…”

“…This work is a continuation of our complex studies [3,5,[11][12][13][14] on the stereochemistry and mechanistic aspects of [3?2] cycloaddition reactions. We have previously [11] determined that reactions of (E)-3,3,3,-trichloro-1-nitroprop-1-ene (1) with ketonitrones take place under relatively mild conditions and lead to adducts with a nitro group at position C4 of the isoxazolidine ring (Scheme 1).…”

A DFT computational study on the [3+2] cycloaddition between parent thionitrone and nitroethene

“…It was found previously that the B3LYP/6-31G(d) calculations illustrate well the structure of TSs in [3+2] cycloadditions involving conjugated nitroalkenes. [23][24][25][26] The critical points on reaction paths were localized in an analogous manner as in the case of the previously analyzed reaction of diazafluorene with cyanonitroethenes. 26 In particular, for structure optimization of the reactants and the reaction products the Berny algorithm was applied.…”

A reexamination of the molecular mechanism of the Diels–Alder reaction between tetrafluoroethene and cyclopentadiene

“…With the aforementioned issues in mind, this work was designed in order to perform quantum-chemical studies of reaction between tetrafluoroethene and cyclopentadiene. The following studies were performed, in particular: (i) an analysis regarding the nature of adduct interactions in the elementary reaction act based on the recently developed [14][15][16][17][18][19] theory of reactivity indices, and (ii) detailed simulations of theoretically possible conversion paths of substrates into products were performed.…”