The Diels-Alder cycloaddition of cyclopentadienone derivative 3-methyl-5,6,7,8-tetrahydroazulen-1(4H)-one with a series of maleimide derivatives is studied using Molecular Electron Density Theory at the B3LYP/6-311++G(d,p) computational level. Conceptual Density Functional Theory analysis predicts low reaction polarity, which is confirmed by global electron density transfer analysis at the transition structures. Topological analysis reveals the electron distribution and evolution of multiple covalent and non-covalent interactions at the transition structures. The results indicate that these Diels-Alder reactions follow an asynchronous one-step mechanism under kinetic control, favouring the endo product formation. Bonding Evolution Theory shows that the reaction mechanism can further be decomposed into five distinct bonding evolution phases. In addition, a molecular docking study is conducted to assess the antimicrobial potential of the reaction products against Escherichia coli and Staphylococcus aureus. An evaluation of the results of binding affinity and molecular interactions concludes that the products are viable as antimicrobial agents.

The (3+2) cycloaddition reactions of 2-diazopropane with derivatives of 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one were investigated using Molecular Electron Density Theory. Calculations were performed at the wB97XD/6-311++G(d,p) level of theory. Conceptual Density Functional Theory indices revealed a low polar character for these reactions, supported by a minimal global electron density transfer at the transition structures, which were classified as forward electron density flux processes. The Electron Localization Function analysis identified 2-diazopropane as a pseudo(mono)radical three-atom component. It further indicated that bond formation does not start at the transition structures. Mechanistically, these reactions proceed via an asynchronous one-step mechanism, ultimately leading to products that are kinetically favored. Furthermore, molecular docking studies were conducted to evaluate the antifungal potential of the reaction products against pathogenic fungal strains, Candida albicans and Aspergillus fumigatus. The docking analysis assessed binding affinities and characterized molecular interactions between the proposed compounds and critical fungal proteins, highlighting their potential as antifungal agents.