Articles written in Journal of Chemical Sciences

    • A conceptual DFT approach towards analysing feasibility of the intramolecular cycloaddition Diels-Alder reaction of triene amide in Lewis acid catalyst


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      The effect of Lewis acid catalysts, TiCl₄ and Et₂AlCl on the intramolecular cycloaddition Diels- Alder (IMDA) reaction of triene-amide have been studied theoretically using the DFT (Density Functional Theory) at the 6-31G(d,p) level of theory. The results obtained using the polar model of Domingo, electrophilicity, nucleophilicity indices and thermochemistry computations, demonstrate that these catalysts are coordinated with more nucleophilic atoms of diene fragment (nitrogen and oxygen of amide group). These catalysts affect negatively the feasibility of the reaction as well as the physico-chemical parameters of the IMDA reaction of triene-amide.

    • An investigation of molecular mechanism and the role of Te-bridged-atom in the formation of polysubstituted pyridines via Hetero-Diels–Alder reaction of isotellurazole with acetylenic dienophile: a molecular electron density study


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      An electron localization function (ELF) analysis and a detailed computational study of the hetero- Diels-Alder (HDA) reaction between isotellurazole and acetylenic dienophile have been performed. Then, B3LYP/Lanl2dz + 6-31+g(d) basis set level has been used to characterize the molecular mechanism and reactivity. The conceptual and computational DFT show that the most favorable regioisomeric product is the ortho/endo adduct, for which the energetic cost is 39.4 kcal/mol. Furthermore, ELF topological analysis envisages that the electron density of the pseudo-radical centers of the most electrophilic and nucleophilic atoms of the molecules come mainly from the charge transfer which takes place along the reaction pathway. The high asynchronicity of the bond formation means that two-stage one-step is the most appropriate mechanism for this reaction. However, the weak electronic contribution of the heavy chalcogen-bridged Tellurium atom in the C1-Te-N2 sequence has increased the activation barrier of the reaction. Otherwise, it has assisted the easy removal of the atom in theintermediary cycloadduct in the end of the reaction leading to the polysubstituted pyridine. So, despite the fact that Te atom is electronically rich, it plays a marginal role for improving reactivity of this [4+2] cyclo addition process.

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