Current Organic Chemistry - Volume 30, Issue 4, 2026

Many parasitic diseases elicit significant immune responses, although these responses can sometimes be excessive or dysregulated, contributing to immunopathology. Moreover, the emergence of parasite clones and gene mutations has led to clinical resistance to widely used antiparasitic drugs, resulting in treatment failures and reduced drug efficacy. Consequently, there is an urgent need for new and alternative antiprotozoal therapies, including the enhancement of existing drug structures. Triazole-based compounds, known for their excellent pharmacological profiles, have shown promise in treating a variety of parasitic infections. The combination of triazoles with other nitrogen/oxygen/sulfur-based heterocyclic compounds presents a promising strategy for the effective clinical management of parasitic diseases. This review highlights recent advancements in the development of triazole hybrids and their structure-activity relationships, providing valuable insights for the design of more potent antiparasitic drugs.

Dimroth rearrangement is a type of molecular rearrangement involving the interconversion of triazoles under acidic or basic conditions. It is particularly significant in heterocyclic chemistry, and it involves the migration of substituents around the nitrogen atoms in the ring system. This review concerns the formation of fused five-membered 1,2,4-triazolo[4,3-c]pyrimidines from their corresponding 4-hydrazinopyrimidine derivatives. Additionally, it discusses their Dimroth-type rearrangement into the thermodynamically more stable 1,2,4-triazolo[1,5-c]pyrimidine isomers under various reaction conditions. Moreover, it was observed that the presence of an acid, base, and aliphatic substituents in C3 and C5 of triazolo[4,3-c]pyrimidine structure facilitates the Dimroth-type rearrangement. In general, the two isomeric series differ significantly in their melting points, proton NMR chemical shift positions, and UV absorption wavelengths.

A well-known heterocyclic scaffold, imidazopyridine, is recognized for its important role in the development of therapeutic drugs. This is because imidazopyridine possesses a wide range of biological characteristics. The aim of this study is to provide a comprehensive outline of various synthetic techniques (2018˗2024) employed in the synthesis of Imidazo[1,2˗a] pyridine derivatives, highlighting both traditional and modern methodologies. The review article includes approaches like one-pot and microwave˗assisted synthesis in addition to traditional multistep synthesis. The review also looks at green chemistry strategies, emphasizing environmentally friendly techniques that reduce the usage of dangerous solvents and reagents. It includes forty different synthetic strategies, with respect to “green” methods, “one˗pot” reactions, “microwave˗assisted” methods, and “cyclization˗based” strategies. This review aims to assist researchers in selecting the most effective strategies for the efficient synthesis of imidazopyridine derivatives, thereby promoting their broader application in medicinal chemistry and related fields.

The alarming rise in life-threatening infections caused by Gram-positive and Gram-negative bacteria has become a significant global health concern, urging the scientific community to explore new therapeutic solutions. Among heterocyclic compounds, the quinoline nucleus has emerged as a versatile scaffold with diverse pharmacological properties. Naturally occurring quinoline-based compounds provide a foundation for designing novel semi-synthetic and synthetic derivatives with broad-spectrum antibacterial activity. Quinoline-fused derivatives have shown potent anticancer effects by targeting critical enzymes and proteins, including topoisomerase I, telomerase, farnesyl transferase, Src tyrosine kinase, and protein kinase CK-II. Additionally, these compounds exhibit antitubercular, anticonvulsant, analgesic, and anti-inflammatory activities. Their potential as cardiovascular agents, acting as calcium-channel blockers and cAMP phosphodiesterase III inhibitors, further highlights their pharmacological significance. The fusion of quinoline with other heterocyclic systems such as indoles, pyridines, triazoles, imidazoles, and pyrazoles presents a promising strategy for drug discovery. Such combinations leverage the individual activities of each moiety, producing synergistic effects and enhancing therapeutic potential. These advances underscore the need for continued exploration of quinoline derivatives to identify novel lead compounds with improved efficacy and broadened activity spectra. This paradigm not only offers a pathway to address pressing antimicrobial resistance but also opens new opportunities for synthetic chemistry and the development of multifunctional therapeutic agents.

Indole derivatives are a significant class of organic compounds with diverse biological activities. They are found in numerous natural products and synthetic drugs, playing a crucial role in medicinal chemistry. In this comprehensive review, we have summarized the synthetic approaches and biological evaluations of a variety of indole derivatives. We analyzed in vitro and in vivo studies assessing the bioactivity of indole derivatives, focusing on structure-activity relationships. The versatility and efficacy of indole-based compounds hold great potential for advancing medical therapies, particularly in the fields of cancer treatment, infectious diseases, and inflammatory disorders. This concise review aims to inspire further research on indole-based compounds for drug development.