Current Organic Chemistry - Volume 28, Issue 9, 2024

For several decades, aromatic azides have been applied in diverse areas of research like synthesis of organic compounds, novel materials and photoaffinity labeling of biomolecules. The discovery of click chemistry and bioorthogonal chemistry expanded their applications. Currently, they are extensively used in biology, biochemistry and medicine. For many years, aromatic azides were usually prepared using nucleophilic substitution. In this classical procedure, commercially available anilines are first converted into aryl diazonium salts which in turn are transformed into aromatic azides by nucleophilic substitution with sodium azide. However, this procedure is rather inconvenient experimentally since it requires the use of strong acids and low temperatures. In recent years, several alternative procedures have been developed. In the present review, we present the synthesis of aromatic azides by means of different experimental methodologies.

This comprehensive review explores the advancements in catalytic transformation, focusing on the use of heterogeneous catalytic systems with a particular emphasis on polymeric-supported palladium (Pd) complexes. This study explores the limitations associated with conventional homogeneous reagents, emphasizes the transition to ecofriendly catalytic systems, and emphasizes the importance of Pd nanoparticles. These nanoparticles are particularly noteworthy for their distinctive properties, including elevated catalytic activity, making them promising for various applications in organic synthesis. The review thoroughly examines the design and synthesis of heterogeneous catalysts, emphasizing the crucial selection of safe and recyclable supports to augment the longevity and reusability of metallic catalysts. Diverse polymer varieties, including polystyrene (PS), polyethylene (PE), polyacrylate derivatives, polyethylene glycol (PEG), and grafted polymers, are investigated as viable supports for Pd complexes. The authors intricately describe the synthesis techniques for these polymer- supported Pd catalysts and furnish illustrative examples showcasing their effectiveness in organic transformation. This comprehensive review additionally highlights the synthesis of polymer-supported palladium (Pd) materials and discusses their applications in electrochemistry. The focus extends to the electrocatalytic properties of Pd-based polymeric nanomaterials, showcasing their effectiveness in glucose sensing, hydrogen peroxide detection, and the sensing of other biological analytes. Furthermore, the catalytic capabilities of Pd nanoparticles in various electrochemical applications, including wastewater treatment and electrochemical capacitors, are explored. Integrating polymer-supported Pd materials into these electrochemical processes underscores their versatility and potential contributions to advancements in catalysis and electrochemical sensing. Catalytic applications featuring polymer-supported palladium complexes with polymeric ligands in organic synthesis processes use the Sonogashira reaction, Suzuki-Miyaura coupling, Heck reaction, Catalytic asymmetric transformations, etc. The subsequent section of the paper focuses on the creation of polymeric palladium complexes, achieved by the complexation of polymeric ligands with palladium precursors. It delves into noteworthy examples of catalytic processes employing polymer-supported palladium complexes featuring polymeric ligands, emphasizing distinct polymers, such as PS, PE, polyacrylate derivatives, PEG, and grafting polymers. The review concludes by exploring catalytic asymmetric transformations using chiral palladium complexes immobilized on polymer supports and discusses various chiral ligands and their immobilization on polymer supports, emphasizing their application in asymmetric allylic alkylation. The review furnishes a comprehensive summary of recent advancements, challenges, and prospective avenues in catalytic oxidation facilitated by polymer-supported palladium catalysts with electrochemical applications.

Andrographolide, derived from the plant Andrographis paniculata (AP), exhibits a diverse range of biological activities, encompassing anti-bacterial, anti-tumor, antiinflammatory, anti-obesity, anti-viral, anti-fibrotic, hypoglycemic, and immunomodulatory properties. Notably, numerous analogues of andrographolide have been synthesized, incorporating significant chemical structural modifications to enhance bioavailability and druggability. A comprehensive exploration into their molecular and cellular mechanisms of action has also been undertaken, enriching our understanding. The investigation highlights the potential of related terpenoid analogues from Andrographis paniculata, beyond the diterpene lactone andrographolide, to hold promise in disease treatment due to structural similarities and diverse pharmacological effects. This review offers insights into the anticipated synthesis and therapeutic applications of andrographolide derivatives across a spectrum of disorders.

In the current study, a zinc-linked amino acid complex was successfully synthesized as an efficient and recoverable catalyst for the synthesis of dihydro pyrano thiazole derivatives via the reaction of an aromatic aldehyde with malononitrile and rhodanine in one-pot, three-component reaction under green conditions. The structures of the new compounds were elucidated by elemental and spectral analyses. Environmental friendliness, low cost, operational simplicity, extensive reusability and applicability, and easy recovery of the catalyst using simple methods are the critical features of this methodology. Moreover, a series of dihydro pyrano thiazole derivatives were synthesized. This new procedure has presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, short reaction time, excellent yields, and high purity without using any hazardous solvents.

Complexes of cobalt(II) chloride with 1-propargylimidazole, 1-propargyl-2-methylimidazole, and 1- propargylbenzimidazole ligands were synthesized and studied by FTIR spectroscopy and X-ray analysis. According to the X-ray analysis, the crystal molecules of compounds were connected by non-covalent interactions, such as halogen bonds and π-stacking. The nature and energy of coordination metal-ligand and noncovalent bonds for structures under study were estimated in the frame of QTAIM (Quantum Theory “Atoms In Molecules”). The antimicrobial activity of obtained cobalt(II) chloride complexes was evaluated in relation to microorganisms E. durans, B. subtilis, and E. coli. Complexes of 1-propargyl-2-methylimidazole and 1- propargylbenzimidazole with cobalt(II) chloride demonstrated high activity against E. coli and E. durans relatively and could be recommended as antimicrobial drugs.

Cardiovascular disease is one of the primary causes of death. Atherosclerosis produces artery constriction or obstruction, which can lead to a heart attack or stroke. Cholesteryl Ester Transfer Protein (CETP) is a protein that aids in reverse cholesterol transport. It promotes cholesteryl ester transfer from HDL to LDL and VLDL. So, inhibition of CETP by drugs limits cardiovascular disease by decreasing LDL and increasing HDL cholesterol. In this study, ten ortho-fluoro substituted benzenesulfonamides 6a-6j were prepared, and their structure was fully determined using ¹H NMR, ¹³C NMR, HR-MS, and IR. In vitro biological evaluation showed that compound 6d has the highest inhibitory activity with 100% inhibition, while compounds 6a-6c and 6e-6j had activities ranged from 29% - 83% at 10 μM concentration. Interestingly, para-substituted derivatives (6d, 6g, and 6j) were observed to have greater CETP inhibitory activities than their ortho- and meta- analogues irrespective to the nature of substituent, i.e., CH3, Cl, or NO2. Ligandfit docking experiment revealed the difference in the binding mode among the synthesized compounds, which is reflected in their CETP inhibitory activity.

Organocatalyst 1,4-diazabicyclo [2.2.2]octane (DABCO) has proven to be an efficient and environmentally friendly catalyst in the multicomponent reaction involving aldehydes, ethylenediamine, and thioglycolic acid under microwave conditions. DABCO stands out among other organic catalysts due to its cost-effectiveness, non-toxic nature, and environmentally conscious profile. The method employed in this study exhibited exceptional attributes, such as high yields, swift reaction times, atom economy, catalyst reusability, and minimal catalyst loading. Additionally, there were excellent yields of products (90-94%). The melting points, UV-Vis, IR, ¹HNMR, ¹³CNMR, were used to analyze the produced compounds. The invitro antibacterial activity of the synthesized compounds was investigated against pathogenic strains E. coli and Bacillus supstalis, and the results obtained were further explained with the help of DFT and molecular orbital calculations. Moreover, the compound 4b was found to be the most potent antibacterial agent amongst all tested compounds.