A three-step method for obtaining pyrrolo[1,2-a]pyrazine-4,7-dicarboxylates was presented. The method involves the N-alkylation of 5-formylpyrrole-3-carboxylates with bromoacetate, followed by the aminoalkenylation of the N-alkoxycarbonylmethyl group using dimethylformamide di-tert-butyl acetal, and further annulation of the pyrazine ring in the presence of ammonium acetate. Procedures for selective hydrolysis, halogenation, arylation, and alkynylation of the synthesized dicarboxylates were described. The in silico evaluation of the potential bioactivity of the synthesized dicarboxylates 4a–f, dicarboxylic acids 7a–c,e, halogenated dicarboxylates 8f–j, and dicarboxylic acids 10a–e was carried out. As seen from the screening of antimicrobial activity, the synthesized compounds 7a–e, 8c,f–j, 10a–e exhibit inhibitory and bactericidal activity against several bacteria and fungi. The highest activity against Klebsiella pneumonia, Staphylococcus aureus, and Bacillus subtilis has been established for the compound 8f with a MIC of 15.625 µg/mL, and the highest antifungal activity against Candida albicans was found for the compounds 8f, 8g, and 8i (МІС=15.625 µg/mL). The molecular docking data show that the compound 8i has the highest affinity to the ThiM Klebsiella pneumoniae kinase, and compounds 8i, 8j are noted for their highest affinity to the DNA gyrase from Staphylococcus aureus.

Thiazolo[3,2-a]pyrimidines are structural analogues of biogenic purine bases, thus may be considered as potential purine antagonists. The synthesis of these heterocyclic systems attracts significant attention from researchers in the field of organic and medicinal chemistry due to their wide range of biological activities, e.g. anti-inflammatory, antimicrobial, antioxidant, antiviral, and anticancer. The high bioactivity of thiazolo[3,2-a]pyrimidine derivatives stimulates the development of fundamentally new synthesis options, which include modern catalytic, microwave and ultrasonic methods for activating cycloaddition reactions, and the improvement of already known methods. This, in turn, became a strong basis for summarizing and systematizing the existing array of literature sources from 2000 to 2024 relating to the methods of obtaining and biomedical profile of thiazolo[3,2-a]pyrimidines and their hydrogenated analogues.

The Giese reaction is a key method for forming C–C bonds via the radical addition to electron-deficient alkenes. Recent advances have shifted this transformation towards photocatalytic approaches that use visible light to generate carbon-centered radicals under mild and sustainable conditions. This review highlights developments from 2020 to 2025 in photocatalytic radical generation using metal-based complexes (especially ruthenium and iridium) and organic photocatalysts. Emphasis is placed on how light-driven processes enable efficient, selective, and environmentally friendly Giese-type reactions with diverse substrates. These innovations demonstrate the growing importance of photochemistry in modern radical synthesis.

The method for the synthesis of ethyl 4-[3-(ethoxycarbonyl)-1-phenyl-1H-pyrazol-4-yl]-2-oxo/thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates was developed, and the bioactivity of the obtained compounds against infectious agents was predicted. Docking studies of the synthesised compounds were performed on pteridine reductase 1 (PTR1) of Leishmania, dihydrofolate reductase–thymidylate synthase of Trypanosoma cruzi, and human dihydrofolate reductase. The results demonstrated that the investigated compounds exhibit high affinity for these enzymes. Moderate selectivity relative to human DHFR was also observed. In addition, the predicted drug-likeness, ADME-Tox parameters, and toxicity profiles suggest the potential of the synthesised compounds for further pharmacological development.

A number of 5-dichloromethylidene-4-sulfonyliminohydantoins were synthesized by the reaction of 2-amino-3,3-dichloroacrylonitrile (ADAN) with aryl and alkyl isothiocyanates. These products are polyfunctional molecules that are considered as initial materials for the synthesis of bioactive compounds. The method of such derivatives multigram synthesis was optimized; also, the features of purification were described, and the main products of reaction mixture alcoholysis (acyclic carbamates) were identified for the first time. A number of modifications was carried out on the example of 5-dichloromethylidene-4-tosyliminohydantoin, namely: alkylation, hydrolysis of the amino group with subsequent arylation, substitution reaction with S-nucleophile, Suzuki – Miyaura coupling, and reduction of the dichloromethylidene fragment to the methyl group. The anticancer activity of 5-dichloromethylidene-4-tosyliminohydantoin was shown.

It has been shown that 3-formylpyrazolo[1,5-a]pyrazine-4-carboxylates obtained by the selective formylation of pyrazolo[1,5-a]pyrazine-4-carboxylates react with 1,2-ethanediamine or 1,3-propanediamine in methanol at room temperature to give pentaazacyclopenta[d]acenaphthalenes or pentaazaaceanthrylenes.