Letters in Organic Chemistry - Volume 20, Issue 3, 2023

Background: 1,1-Bishydroperoxides are used as oxidizing agents, radical initiators, in addition, studies of biological activity show the promise of this area of research. Objective: There are currently no kinetic data on the thermal stability of these peroxides in various solvents. Therefore, we investigated the thermal stability of 1,1-dihydroperoxycyclohexane as the most widely used at present. Methods: The rate constants and activation parameters were measured at the temperature range of 100- 170°C in the presence of 2-naphthol, which inhibits the induced decomposition of the peroxide by free radicals. Peroxide concentration was determined by iodometric method. Results: The rate constants of the reaction with the solvents and of the monomolecular decomposition of the peroxide were determined. Conclusion: The use of DHPC as a radical initiator requires taking into account its reactions with the solvent and/or monomer, in addition to its monomolecular decomposition with the formation of free radicals.

Quinoline ring system is extensively dispensed in natural products, especially in alkaloids. Moreover, thieno[2,3-b]quinolines have vast biological activities, including urea transporter inhibition, anti-microbial, antitumor, antioxidant, anti-inflammatory, and antiproliferative EGFR tyrosine kinase inhibition. Vilsmeier-Haack is considered the most facile and promising set of synthetic routes, leading to 2-chloro-3-formylquinolines through Vilsmeier-Haack cyclisation of N- arylacetamides, which are subsequently used as key intermediates for the synthesis of thieno[2,3-b]quinolones (Tqs). Many varieties of thieno[2,3-b]quinolines (Tqs) ring systems, specifically concerning medicinal chemistry, have been developed over the past decade. In light of these facts, this review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of thieno[2,3-b]quinolines through the Vilsmeier-Haack reaction. In this study, the methods of preparation and the chemical reactivity of (Tqs) by using the Vilsmeier-Haack reaction are discussed. Since the beginning of the 21st century, they have been advancing towards synthesizing substituted Tqs. It can be concluded that substituted Tqs can be used as building blocks for the synthesis of polyfunctionalized heterocyclic compounds with pharmacological interest.

Amides are a critical class of widely distributed heterocycles in nature. The preparation of amides from benzoic acids and dicarbodiimides under catalyst-free conditions was reported. Various products were obtained in good to high yields. The model reaction could be scaled up to the gramscale level. A reaction mechanism was proposed based on control experiments and relevant literatures.

The weak interactions between epinephrine and thymine were investigated by combining the 6-311+G(d,p) basis set with the M06-2X method based on density functional theory. Results suggest that epinephrine and thymine form 22 steady geometries through weak interactions, which primarily contain hydrogen bonds and π–π stacking. Hydrogen bonding is the main character. In addition, the interaction energies range from −20.98 kJ·mol⁻¹ to −63.14 kJ·mol⁻¹, with the basis set superposition error correction, which are in line with the energy range of the hydrogen bond. Geometrical parameters, frequency analysis, natural bond orbital (NBO) analysis, atoms-in-molecules (AIM) analysis, and reduced density gradient (RDG) analysis were also used to analyze and verify hydrogen bond formation. Most of the hydrogen bonds in optimized structures of the epinephrine–thymine complex are closed-shell interaction and electrostatic dominant, whereas N···H–N, which exist in geometries 3, 4, 5, and 14, are interacting between the closed-shell and shared-shell. N-H…N is almost linear, which is more conducive to the study of the role of hydrogen bonds in the system.

This article proposes a new and facile method to prepare a carbon-based catalyst entitled graphene oxide quantum dots that contain nitrogen-doped groups (GOQDs-N-doped), and which are bioactive and safe possessing economical free transition metal properties. In this study, GOQDs-Ndoped was synthesized by means of the pyrolysis of citric acid at 180°C in the presence of ammonia. The prepared catalyst, which embodies an amorph and 3D structure, acts similar to nanoreactors, and was successfully used in the synthesis of tetrahydropyridines (THP) derivatives with antimicrobial, anticancer, antifungal and anti-Alzheimer’s properties through five-component reactions. We believe that the production of affordable and green carbocatalysts to be used in multi-component reactions and in chemical and pharmaceutical industries can be promising. Finally, we were able to synthesize highly substituted and efficient Tetrahydroperidines by utilizing laboratory-produced carbocatalysts.

Kadsura coccinea has been used as a folk medicine in China, treating various diseases, including chronic gastritis and rheumatoid arthritis (RA). Chemical studies have revealed that lignans and triterpenes are the main constituents of its roots and stems. In this paper, a chemical investigation on the stem of K. coccinea was performed and a previously undescribed 3,4-secolanostane (1) was afforded. The structure of 1 was determined through comprehensive NMR and HRESI-MS data analysis. The stereo-configuration of 1 was established based on a comparison of experimental and calculated ECD spectra. Bioactivity assay carried out in immune cells indicated that 1 could show moderate effects on ConA (5 μg/mL)-induced T-cell proliferation with an IC50 value of 13.28 μM (cyclosporine A as the positive drug, IC50 = 0.13 μM) while the IC50 value was 23.12 μM in LPS (10 μg/mL)-induced B cells (mycophenolate mofetil as the positive drug, IC50 = 16.71 μM).

Glycyrrhiza uralensis has been used as a traditional medicine for generations. Chalcones are one of the typical chemical constituents of G. uralensis. In this paper, phytochemical research on roots of G. uralensis was performed, leading to the isolation and identification of a previously undescribed chalcone glycoside (1). Its structure was established by means of comprehensive spectral analysis and acid hydrolysis. Moreover, the bioactivity assay revealed that 1 showed a promotive effect on IEC-6 cell proliferation and evidently reversed DFMO-driven IEC-6 cell growth arrest. The results indicated that 1 might be used for the maintenance of intestinal epithelial homeostasis.

A new series of bisthiosemicarbazide and bistriazole molecules bridged quinazolinedione was synthesized and characterized by FT-IR, ¹H and ¹³C-NMR spectral data. Antiurease activities of all new compounds were tested according to the phenol-hypochlorite method by Weatherburn. All compounds have effective urease inhibition activities compared to the standard inhibitor thiourea and previously synthesized quinazolinones as potential inhibitors. Bistriazoles containing quinazolinedione have the best inhibition results. 1,3-Bis[(4-ethyl-5-mercapto-4H-1,2,4-triazol-3-yl)methyl]quinazoline- 2,4(1H,3H)-dione (5b) has the best inhibitory activity with 1.25 ± 0.45 μg/mL IC50 value.

We successfully synthesized novel silica-supported Ni (II)-PLP-ONNO Schiff base/SBA- 15 complex, as a mesoporous catalyst, whose characterization was determined using X-ray diffraction analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma-atomic emission spectroscopy, nitrogen adsorption desorption isotherms (BET-EDX) and (BET-BJH), and thermo-gravimetric analysis. A fabricated catalyst was employed for facile and efficient, one-pot production of various benzothiazole heterocycles by cyclocondensation reactions of 2-amionthiophenol and benzaldehyde compounds under green and mild conditions with good to excellent yields. The prepared nano catalyst can offer high stability, excellent activity, easy separation, and reusability, as well as environmentally friendly, compared to its homogeneous compounds.

Determination of the exact structure of any compound is an extremely critical task. Primarily organic chemistry relies on NMR, IR & Mass spectrometric data. Authors have experienced that introduction of structure elucidation in undergraduate courses and postgraduate courses are helpful for students later in their research careers. Based on our experience, this article discusses double bond equivalents, the rule of 13 and the nitrogen rule. We have compared the result of these three rules with real spectroscopic data. This article demonstrates the applicability of double bond equivalents, the rule of 13 and the nitrogen rule in solving compound structures using spectroscopic data. Based on the availability of molecular weight or molecular formula, we can predict the possible structure of any organic compound using these concepts. In addition, if we have spectroscopic data like NMR, IR, Mass spectrometry data and UV spectrophotometry data, we can easily confirm the exact structure. This article will be critical for all the organic chemist for the structure elucidation of organic molecules; however, several spectroscopic data is still required for analyzing the exact structure of any molecule.