Current Organic Chemistry - Volume 29, Issue 8, 2025

Dihydrocoumarins play pivotal roles as essential components in biologically active molecules, drugs, and flavor and fragrance compounds. In particular, chiral 3,4-dihydrocoumarins exist in natural products, exhibit less toxicity, and possess structural diversity and stability. Consequently, the asymmetric synthesis of these scaffolds has garnered considerable attention within the chemistry community. Recent advancements have witnessed their synthesis achieved through both metal and organocatalyzed approaches. In this review, we analyze and discuss the advancements made in chiral-organocatalyzed asymmetric synthesis of dihydrocoumarins since 2015. This review is structured according to the type of catalyst employed in the transformation, providing a comprehensive examination of the recent developments in this field.

The Corona virus disease-19 (COVID-19) pandemic challenged the scientific community in the search for developing effective treatments, such as medicine and/or a vaccine candidate. The SARS-CoV-2 virus and its variants, Omega, Omicron, and Delta, remain as a major threat to human health, causing significant morbidity and mortality worldwide. Given that computational methods are thought to be quick, easy, and inexpensive, they have been widely used in this scenario to design new anti-COVID-19 drug candidates. In addition, heterocyclic scaffolds have been explored exhaustively for their biological properties and as fruitful sources of new molecular entities to fulfill the chemical space available.In light of this, we intend to highlight the synthetic techniques used to produce novel heterocyclic derivatives that may serve as effective anti-COVID-19 lead candidates by focusing on important viral proteins and using computational tools. Then, the objective of this article, with a theoretical nature, is to contribute to the delimitation of organic chemistry methods to achieve new anti-COVID-19 agents.

As a new type of green solvent, ionic liquids have made rapid progress in the fields of organic synthesis, separation, and electrochemistry due to their unique physical and chemical properties. At the same time, the new fluorescence characteristics and good separation and adsorption functions of ionic liquids have gradually developed in the field of environment and food, showing a good application prospect. Based on the work of our research group and the progress and development of research technology, this article reviews the research results of ionic liquids in environmental monitoring and food detection and extraction in recent years. In the environmental field, ionic liquids have the ability of detection and remediation and they show the advantages of fast, efficient, green and recyclable in the detection of environmental pollutants. In the field of food, ionic liquids provide a new idea for the detection and extraction technology of food components. While ensuring green, safe and pollution-free, they show superior selectivity, repeatability and stability, and simplify the operation steps and costs to a certain extent, showing the capture vitality with life characteristics. As a potential smart material, the mechanism of ionic liquids as fluorescent probes and separation extractants was discussed. Finally, the future development and research directions of ionic liquids are prospected, and it is expected to realize the intelligentization of ionic liquid materials and the general integration of development.

Hydrazides, derivatives of hydrazine, are widely used in pharmaceuticals, polymers, dyes, herbicides, and as chemical preservatives. A notable application is in synthesizing 1,3,4-oxadiazole, an important aromatic compound with a five-membered heterocyclic ring containing two nitrogen atoms and one oxygen atom. Among the four oxadiazole isomers, 1,3,4-oxadiazole is the most significant, used in drug discovery, pharmaceuticals, and dyes. It is synthesized from various substituted hydrazides or hydrazones using reagents like copper, cobalt, cerium, phosphorus oxychloride, mercury oxide, potassium iodide, triflic anhydride, and carbon disulfide. This study reviews the synthesis methods of 1,3,4-oxadiazole, highlighting the advantages and disadvantages of different catalysts and conditions, providing useful insights for researchers.

The synthesis of a novel family selenazolo[3,2-a]pyridin-4-ium derivatives in high yields was developed based on the annulation reactions of 2-pyridineselenenyl chloride with unsaturated heteroatom and heterocyclic compounds. The analogous new thiazolo[3,2-a]pyridin-4-ium derivatives were obtained by the annulation reactions of 2-pyridinesulfenyl chloride. The reactions with vinylic ethers and N-vinylimidazole gave 3-substituted selenazolo[3,2-a]- and -[1,3]thiazolopyridin-4-ium derivatives, whereas reactions with allyl alcohol, allyl chloride, allyl bromide, 3-butenoic, 4-pentenoic and 5-hexenoic acids occurred with the opposite regiochemistry, affording 2-substituted [1,3]chalcogenazolo[3,2-a]pyridiniums. The antibacterial activity of the obtained products against gram-positive and gram-negative bacteria was evaluated, and compounds with high activity were discovered. A comparison of the antibacterial properties of [1,3]selenazolo[3,2-a]pyridin-4-ium derivatives with their sulfur analogs shows a higher activity of the selenium compounds.