This study employs Molecular Electron Density Theory (MEDT) to explore the [3+2] cycloaddition mechanisms involving 1-methyl-4-(prop-1-en-2-yl)cyclohex-1-ene (2-R) and nitrile oxide (3-R). Density Functional Theory (DFT) calculations using the B3LYP/6-311(d,p) method were performed to determine reactivity indices, activation energies, and reaction energies. The conceptual DFT analysis indicates that 1-methyl-4-(prop-1-en-2-yl)cyclohex-1-ene 2-R acts as a nucleophile, while nitrile oxide 3-R functions as an electrophile. The reaction exhibits notable chemoselectivity and regioselectivity, supported by activation energies that align with experimental data. BET analysis suggests a one-step mechanism with asynchronous bond formation. Additionally, molecular docking studies of the reaction products against HIV-1 and COVID-19 reveal that the presence of oxygen and nitrogen atoms enhances the interaction energy with proteins, indicating potential therapeutic benefits.

Molecular electron density theory has been performed with the B3LYP/6-31(d,p) method to study the [3+2] cycloaddition processes between azidobenzene and propionaldehyde, the reactivity indices, activation and reaction energies are computed. The reaction and activation energies indicate that this [3+2] cycloaddition reaction is regiospecific, in good agreement with the experimental results. ELF examination revealed that the mechanism of these cycloaddition reactions takes place in two steps. In addition, a docking approach was performed on the products investigated, and the interaction with the protein protease COVID-19 (PDB ID: 6LU7), the results confirm that the presence of triazole and isoxazole rings increases the affinity of these products.

The inhibiting effect of chloroquine compounds (ChCs) on the SARS-CoV-2 virus represents a highly debated form of study owing to the emerging proposals of mechanistic implications for exploring the mode of action of ChCs on the virus. Keeping in view the emerging significance of chloroquine derivatives, the present study was performed to screen one hundred and ninety known chloroquine derivatives for their interaction with several SARS-CoV-2 target proteins by molecular docking and molecular dynamics simulations to obtain an in-depth understanding of the potential hits of these compounds against SARS-CoV-2. A total of 190 molecules from the chloroquine family were screened for the identification of potential new inhibitors of the three therapeutic target proteins of SARS-CoV-2, namely Mpro (master protease), PLpro (papain-like protease) and SGp-RBD (spike glycoprotein receptor binding domain). The ChCs bound to SARS-COV-2 Mpro, PLpro, and SGp-RBD were generated by molecular docking and molecular dynamics simulations. Herein, a comparative analysis of chloroquine family products and a well-known drug against SARS-CoV-2, called Remdesivir, has also been presented. This investigation is intended to study the mechanism of interaction between ChCs and the SARS-CoV-2 virus and explore the unprecedented areas associated with the inhibitory activity of ChCs against this virus.