The regioselectvity and the mechanism of the (32CA) cycloadditions reactions of 1-bromo-4-vinylbenzene 1 and 1-chloro-4-vinylbenzene 2 with benzonitrile oxide 3 were investigated under the molecular electron density theory (MEDT) at the B3LYP/6-311++G(d,p) computational level. Evaluation of the ELF reveals that these zwitterionic type (zw-type) 32CA reactions take place in a two-stage one-step mechanism. This MEDT study shows that the meta isoxazolines are kinetically and thermodynamically favored over the ortho ones, these 32CA reactions being completely regioselective, in agreement with experimental outcomes. In addition, the efficiency of isoxazolines against SARS-CoV-2 have been also investigated. According to the docking analysis, the present study concludes that 5-(p-bromophenyl)-3-phenyl-2-isoxazoline (B-m) shows better interactions for the inhibition of SARS-CoV-2 in comparison to chloroquine.

Diels–Alder [4 + 2] cycloaddition a reaction between 2-nitro-1H-pyrrole and isoprene was examined within the Molecular Electron Density Theory (MEDT) by employing DFT functional combined with B3LYP/6–31(d). Conceptual DFT (CDFT) analysis allows to characterizing 2-nitro-1H-pyrrole as a nucleophile and isoprene an electrophile, whilst examination of the Parr functions permit explanation the chemo- and regioselectivity observed experimentally in total conformity with the barrier activation. Electron localization function (ELF) topological investigation of some points along intrinsic reaction coordinate (IRC) profile associated with the most favorable reaction channel permits to establish a non-concerted two stage one-step molecular mechanism.

Since the epidemic of COVID-19 was declared in Wuhan, Hubei Province of China, and other parts of the world, several studies have been carried out over several regions to observe the development of the epidemic, to predict its duration, and to estimate its final size, using complex models such as the SEIR model or the simpler ones such as the SIR model. These studies showed that the SIR model is much more efficient than the SEIR model; therefore, we are applying this model in the Kingdom of Morocco since the appearance of the first case on 2 March 2020, with the objective of predicting the final size of the epidemic.

[This corrects the article DOI: 10.1155/2020/9769267.].