Current Organic Chemistry - Volume 28, Issue 10, 2024

In recent times, many research groups have focused their attention on nitrogencontaining heterocyclic compounds with the aim of gaining a deeper understanding of their biological characteristics. Among them, molecules based on 1,2,3-triazole and benzimidazole have exhibited diverse biological applications and are present in many drug molecules. The purpose of this review is to describe various benzimidazole-1,2,3-triazole hybrids and to provide a comprehensive evaluation of their biological properties. The compounds discussed in this study have been synthesized through a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction between diverse azides and alkynes, utilizing a 1,2,3-triazole scaffold as a linkage between two connecting groups. The synthesis of several benzimidazole-1,2,3- triazole hybrids is covered in this review, along with a biological assessment of their anticancer, antiproliferative, antitubercular, antibacterial, antidepressant, and other activities. Moreover, in our opinion, this review may be useful for the development of various medicinally significant molecules.

The Nazarov reaction involves the cyclization of divinyl ketones into cyclopentenones under the influence of strong acids. The prevalence of five-membered carbocycles in a multitude of natural and bioactive products has triggered an intense development of efficient methods for their construction. In particular, asymmetric versions of the Nazarov reaction are achieved by using either a chiral auxiliary or a chiral catalyst, which can be an organocatalyst, a metal catalyst, or a multicatalytic system. This review aims to update the field of asymmetric Nazarov reactions published since 2017. It is divided into four sections, dealing successively with Nazarov reactions of chiral auxiliaries, organocatalytic enantioselective Nazarov reactions, metal/boron-catalyzed enantioselective Nazarov reactions, and multicatalytic enantioselective Nazarov reactions. Each section of the review is subdivided into simple asymmetric Nazarov reactions and Nazarov-based domino/tandem reactions, which have allowed numerous more complex functionalized chiral molecules to be synthesized in one-pot procedures.

In this study, magnetic hercynite nanoparticles (FeAl2O4, MNPs) were functionalized by cheap and readily available tris(hydroxymethyl)aminomethane (Tris) as an organocatalyst. Various techniques, including Vibrating Sample Magnetometry (VSM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TG) were employed to determine the morphology, particle size, physical properties, and magnetic properties of the nanoparticles. Additionally, Fourier transform infrared spectroscopy (FT-IR) techniques were used to investigate the presence of the functional group. The activity of this new catalyst as a magnetically recoverable nanocatalyst was investigated in the synthesis of oxygen and nitrogencontaining heterocyclic compounds. Pyranoprazole and 2-amino-4H-benzo[b]pyrans compounds were synthesized with high efficiency in a short time. FeAl2O4@SiO2@Tris can be separated using magnetic attraction and reused up to 5 consecutive times without a significant decrease in the yield of target products or catalytic activity.

Due to very good biological activity and use as fluorescent probes, coumarin synthesis and developing new synthesis methods are still an attractive area for many research groups. In this work, for the first time, a novel, mild, and green method has been developed for coumarin synthesis by using supercritical diethyl ether as a reaction medium. The optimum conditions for the synthesis of 3-acetylcoumarins and 4-methylcoumarins have been explored. These newly established techniques could be a favourable approach against two traditional synthetic routes in terms of green chemistry criteria for the synthesis of important intermediates, 3-acetyl coumarins and 4-methyl coumarins. 4-Methyl coumarins have been obtained in good-to-excellent yields (63-87%); for example, bmethylumbelliferone, a naturally bioactive coumarin compound, was synthesised in 30 min at 200oC, resulting in 87% yield, while several 3-acetyl coumarins were synthesized in very good yields (28- 96%).

A total of twelve pentacyclic triterpenoid derivatives based on betulin (1) and lupeol (2) scaffolds isolated from Diospyros foxworthyi were hemisynthesized by acylation or acetylation reactions with appropriate acid chloride or acetic anhydride. The structures of the hemisynthesised compounds were characterised by means of FT-IR, 1D- and 2D-NMR, as well as HRMS analysis. These compounds were assayed for in vitro anti-malarial studies by inhibition of β-hematin formation assay with chloroquine as a positive control. Compounds 1d and 2f showed the strongest potential as β-hematin formation inhibitors with IC50 values of 6.66 ± 1.36 and 11.89 ± 0.15 μM, respectively, compared with the positive control (chloroquine; IC50 = 37.50 ± 0.60 μM). In silico molecular docking simulations were performed using AutoDock Vina for compounds 1d and 2f to investigate the binding interactions and free energy of binding (FEB) with the hemozoin supercell crystal structure (CCDC number: XETXUP01). The findings revealed several hydrophobic interaction modes between the 1d, 2f and hemozoin, with calculated FEBs of -8.4 ± 0.2 and -8.9 ± 0.0 kcal mol-1, indicating strong and favourable interactions.