Theoretical Evaluation of Global and Local Electrophilicity Patterns to Characterize Hetero-Diels−Alder Cycloaddition of Three-Membered 2H-Azirine Ring System

Abstract

Present communication elicits an interesting interaction between 2H-azirine and a number of electron rich and electron deficient dienes. A series of substituted 2H-azirine 1-10, and three dienes namely cyclopentadiene D-1, furfural D-2, and dinitrofuran D-3 were chosen to investigate and critically review the reactivity and selectivity of Diels-Alder cycloaddition strategy. The global and local electrophilicity patterns have been evaluated to interpret the electrophilic/nucleophilic behavior of dienes D-1 to D-3 and dienophiles 1-10, in polar Diels-Alder cycloaddition, using the DFT method at the B3LYP/6-31G* level of theory. Regional nucleophilicity have been evaluated using local nucleophilicity descriptor N(k) (Perez, P.; Domingo, L. R.; Duque-Norena, M.; Chamorro, E. J. Mol. Struct. THEOCHEM 2009, 895, 86-91), and regional electrophilicity at the active sites of the interactive species involved in Diels-Alder processes have been described on a quantitative basis using local electrophilicity index omega(k).

Reactions of the halonium ions of carenes and pinenes: An experimental and theoretical study

“…Just as increasing conjugation in poly-alkenes both lowers the HOMO-LUMO energy gap and increases the polarizability, thus decreasing hardness, we posit that this index can provide a useful metric for comparing relative conjugation between several model bromonium ion systems. While a comparison of hardness has been made between isomers of otherwise identical systems, such as iron (II) complexes [39], or for comparisons of similar reactants of cycloaddition reactions [40], application of the hardness index to compare reactive intermediates across a range of conjugation and electron density delocalization has to our knowledge not been reported. While the theory of using electronic structure to calculate hardness has been developed using DFT, we have also included the results using Hartree-Fock (HF) theory, since there appears to be nothing in the original derivations that requires that DFT be used to calculate MOs and their energies, and in this study DFT-calculated hardness values had some possibly anomalous results, while HF results seemed to be more accurately descriptive of the systems studied, at least qualitatively.…”

Impact of Global and Local Reactivity Descriptors on the Hetero-Diels-Alder Reaction of Enaminothione With Various Electrophiles

“…[21][22][23][24][25][26][27][28] Moreover, recent literature study reveals that global and local descriptors are very useful and reliable tools for the predication of reaction mechanisms. [29][30][31][32][33] Thus exploration of global and local reactivity descriptors to understand the mechanistic aspects for a cycloaddition reaction is worth important.…”

Mechanism and regioselectivity of the 1,3‐dipolar cycloaddition of thiocarbonyl S‐imide with cyclopent‐3‐ene‐1,2‐dione and methoxyethene: a density functional theory approach

“…Similar to FMO theory, many researchers use the hard and soft acids and bases (HSAB) principle, formulated with density functional theory (DFT), to foresee reactivity based upon ground state properties . A number of global and local reactivity descriptors, such as global electrophilicity, global hardness, global softness, local hardness, local softness, condensed Fukui functions, philicity indexes, and so on, based on DFT are powerful tools for the prediction of regioselectivity in 1,3‐DC reactions and widely used in the literatures …”