Chemistry Proceedings

Introduction: According to research data, 1,3-oxazines are pharmacologically active substances, as well as the substrates for the synthesis of heterocyclic and acyclic compounds. However, bis(1,3-oxazin-6-one) derivatives are little studied class of compounds, which makes their research a promising direction for the development of modern synthetic chemistry and pharmacy. The aim of this work is to obtain bis(4-hydroxy-6H-1,3-oxazin-6-ones), study their alcoholysis reaction, prove the structure of the obtained products and evaluate their pharmacological potential in silico. Methods: The reflux of isophthalic acid diamide with a twofold excess of substituted malonyl chloride in 1,2-dichloroethane for 15 h led to the production of bis(4-hydroxy-6H-1,3-oxazin-6-ones) (1, 2). As a result of their reflux with absolute ethanol for 5 h acyclic esters of malonamic acids (3, 4) formed. The structure of the obtained compounds was proved by ¹H and ¹³C NMR spectroscopy. The prediction of biological activity was carried out using the GUSAR and PASS online web resources. Results: The yields of compounds 1–4 were 90%, 90%, 93%, 89%, respectively, depending on the nature of the substituent at position C₅ of the oxazine cycle. According to the in silico assessment of biological activity, bis(1,3-oxazine-6-ones) exhibited high probability of antitumor activity, while ethyl esters of malonamic acids showed promising anxiolytic, antieczematous, fibrinolytic activities. Conclusions: New bridging 1,3-oxazin-6-ones were synthesized. The reaction of their cleavage by absolute ethanol to malonamic acid esters was studied. The potential biological activity was predicted in silico.

Stink bugs (Hemiptera: Pentatomidae and Scutelleridae) produce a wide range of semiochemical compounds that function as pheromones, allomones, synomones, and kairomones. This study aimed to isolate, identify, and synthesize the main semiochemical components of the metathoracic glands of Aelia rostrata, A. melanota, Eurygaster integriceps, and E. maura. Extracts from male and female glands were analyzed using GC–MS, which revealed that (E)-2-hexen-1-ol acetate was the dominant compound in all four species. In addition, several α,β-unsaturated aldehydes with chain lengths of C6–C8, including (E)-2-hexenal, (E)-2-heptenal, (E)-2-octenal, and (E)-2-hexen-1-ol, were detected. These compounds are characterized by strong odors and irritant properties, acting as defensive allomones and alarm pheromones. Synthetic routes were developed for these key compounds. In particular, (E)-2-hexen-1-ol acetate was efficiently synthesized via acetylation of (E)-2-hexen-1-ol using acetic anhydride in the presence of 4-dimethylaminopyridine (DMAP) as a catalyst. This approach significantly reduced the reaction time to 30 min and improved the yield to 90%. Although DMAP is widely used in organic synthesis, the simplicity and efficiency of this optimized protocol for producing semiochemical analogues of stink bugs have not been previously reported. Preliminary trials with synthetic lures indicated their potential for pheromone-based monitoring of stink bug populations in cereal fields. The optimized semiochemical blends developed in this study are expected to contribute to integrated pest management strategies by enabling more effective detection and control of these economically important pests.

The 1st International Online Conference on Separations (IOCS 2025), organized by MDPI during 15–17 October 2025, brings together researchers, professionals, and industry experts from around the world to explore the latest advancements in the dynamic field of separation science [...]