Competition between the one-step and two-step, zwitterionic mechanisms in the [2+3] cycloaddition of gem-dinitroethene with (Z)-C,N-diphenylnitrone: a DFT computational study

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

“…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).…”

“…The mechanistic aspects of [3?2] cycloaddition reactions have recently drawn ever greater attention from organic chemists [1][2][3][4][5][6][7][8][9][10]. It turned out that in the case of reactions including strongly electrophilic dipolarophiles, a stepwise, zwitterionic mechanism may compete with a classical one-step mechanism.…”

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.…”

An experimental and quantumchemical study of [2+3] cycloaddition between (Z)-C-(m,m,p-trimethoxyphenyl)-N-(p-methyphenyl)-nitrone and (E)-3,3,3-trichloro-1-nitroprop-1-ene: mechanistic aspects

“…The quantum chemical simulations were carried out using the B3LYP/6-31G(d) theoretical level 22 . The same approach was recently used for the analysis of [2+3] cycloaddition pathways of diarylnitrones with several dipolarophiles [23][24][25][26] . …”

“…where r TS X-Y is the distance between the reaction centers X and Y at the transition structure and r P X-Y is the same distance at the corresponding product (see 24 ). **) Charge transfer (t) 27 was calculated according to the formula t=-ΣqA; where qA is the net charge and the sum is taken over all the atoms of dipolarophile.…”