Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host’s immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Terpenes are a group of natural products made up of molecules with the formula (C₅H₈)_n that are typically found in plants. They are widely employed in the medicinal, flavor, and fragrance industries. The total synthesis of terpenes as well as their origin and biological potential are discussed in this review.

As part of natural products or biologically active compounds, the synthesis of nitrogen-containing heterocycles is becoming incredibly valuable. Palladium is a transition metal that is widely utilized as a catalyst to facilitate carbon-carbon and carbon-heteroatom coupling; it is used in the synthesis of various heterocycles. This review includes the twelve years of successful indole synthesis using various palladium catalysts to establish carbon-carbon or carbon-nitrogen coupling, as well as the conditions that have been optimized.

Benzothiazole analogs are very interesting due to their potential activity against several infections. In this research, five benzothiazole derivatives were studied using density functional theory calculations. The optimized geometry, geometrical parameters and vibrational spectra were analyzed. The charge distribution diagrams, such as FMO (HOMO-LUMO), energies of HOMO-LUMO, polarizability, hyperpolarizability, MESP and density of states, were calculated. The computed energies of HOMO and LUMO showed that the transfer of charge occurred within the compound. The effect of the change of substituents on the ring on the value of the HOMO-LUMO energy gap was also observed. It was observed that, in this series, compound 4 with CF₃ substituent had the lowest energy gap of HOMO-LUMO, and compound 5 with no substituent had highest HOMO-LUMO energy gap. From the energies of HOMO and LUMO, the reactivity descriptors, such as electron affinity (A), ionization potential (I), chemical softness (σ), chemical hardness (ƞ), electronic chemical potential (μ), electrophilicity index (ω), were calculated. In addition, the ¹³C and ¹H NMR chemical shifts of the molecules were calculated using the gauge-independent atomic orbit (GIAO) method; the shifts were in good agreement with the experimental values. The anti-bacterial potential of compounds 1 to 5 was tested by molecular docking studies toward target proteins 2KAU and 7EL1 from Klebsiella aerogenes and Staphylococcus aureus. Compounds 3 and 1 showed high affinity toward 2KAU and 7EL1, respectively.