Great interest in binuclear aromatic systems containing an isoxazole ring and a sulfamide group is due to the effect of two pharmacophore groups at once on the biological activity of these compounds. This article is devoted to the development of a method for the synthesis of 3-arylisoxazole-containing compounds and their sulfamide derivatives from simple and accessible products of organic synthesis. The target products of the developed multistage schemes are derivatives of various bicyclic systems containing an isoxazole ring and a second aromatic ring associated with a sulfofragment. The synthesis of 3-aryl-5-acylaminoisoxazoles was carried out by sequential conversion of methyl esters of aromatic carboxylic acids into the corresponding nitriles by reaction with acetonitrile in the presence of sodium hydride in dioxane. At the next stage, the nitriles reacted with hydroxylamine in an aqueous solution of sodium hydroxide to form the corresponding bicyclic amines, which were then acylated in acetonitrile with acetic acid chloride in the presence of pyridine. The total yields of 3-aryl-5-N-acylaminoisoxazoles were at least 60%. It was found that the sulfonylchlorination of 3-aryl-5-N-acylamino derivatives of isoxazole, depending on the experimental conditions and the structure of the starting substrates, forms both mono- and disulfochlorides. The regioselectivity of the sulfochlorination reaction of the synthesized bicyclic systems was proved by 1H NMR spectroscopy. The influence of various factors on the course of the sulfochlorination reaction of the synthesized bicyclic systems was studied. The dependence of the direction of the electrophilic attack on the structure of the compounds and on the conditions of the experiment was established. As a result of the performed research, both mono and disulfochlorination products were obtained. With an increase in the reaction time, the disulfonylchlorination product accumulates and the deacylation reaction proceeds in parallel. Convincing proof of the structure of all synthesized compounds has been carried out using a complex of modern methods of physical and chemical analysis.

2,1-Benzisoxazoles or anthranyls have different types of biological activity, are used to obtain monomers for polymeric materials, dyes and other heterocyclic compounds. In addition, 2,1-benzisoxazoles attract the attention of researchers due to the presence of a weak N-O bond, which is a potential place for the opening of the cycle in the reactions of reduction, oxidation, and various transformations. Therefore, it is very important to study their structure, methods of identification and reactivity in the processes taking place with their participation. One of the most effective modern research methods in chemistry is chromatography-mass spectrometry and quantum-chemical modeling. And since the fragmentation of molecules during their electron impact ionization depends on the nature of the compounds and characterizes their reactivity in various types of chemical reactions, the aim of this work was to experimentally and theoretically study the fragmentation of dichloro-3-phenyl-2,1-benzisoxazoles. For this, the corresponding dichloro-3-aryl-2,1-benzisoxazoles were synthesized by condensation of nitroarenes with arylacetonitriles in the presence of an excess of sodium hydroxide. The chromatography-mass spectrometry method was used to study the directions of fragmentation of their molecular ions. It was found that for all the compounds studied, similar fragment fragments are observed in the mass spectra, which indicates similar patterns of their fragmentation. Based on the data of quantum chemical modeling using the PC GAMESS/FireFly 8.2 software package using the density func-tional theory method, it was suggested that even before the decay of the molecular ions of dichloro-3-aryl-2,1-benzisoxazoles, they rapidly transform into the corresponding cation radicals of dichloroacridinones with the same atomic composition. Further decomposition of dichloroacridinone ions is accompanied by the release of a chlorine atom, carbon monoxide and skeletal rearrangement with the formation of the corresponding chlorocarbazole ions. Chlorocarbazole ions then eject a hydrogen chloride molecule to form a cation with m/z 164 and atomic composition C12H6N.

Sulfonamide derivatives of heterocyclic compounds are promising targets for the search for new substances with specific biological activity. They are widely used as inhibitors of human carbonic anhydrases involved in the implementation of various biochemical processes. The presence of several heterocyclic systems in the structure of sulfonamides significantly increases the ability to bind to active sites of carbonic anhydrases and inhibit their activity. Therefore, the development of approaches to the preparation of sulfonamides of polynuclear heterocyclic compounds is of great scientific interest. This article proposes a multistage scheme for the synthesis and characterization of new sulfonamide derivatives of 1-aryl-6-pyrazol-1-yl-pyridazines. The synthesis of substituted pyrazol-1-yl-pyridazines was carried out by sequential conversion of arylpyridazinones by refluxing in phosphorus oxychloride to 3-chloro-6-arylpyridazines, at the next stage as a result of the nucleophilic substitution of activated chlorine in the pyridazine ring with hydrazine, arylpyridazines were obtained with the reaction Refluxing in butanol, the target compounds with a 3,5-dimethylpyrazole structural fragment were synthesized. The study of the regularities of the course of sulfonylchlorination of 1-aryl-6-pyrazole-1yl-pyridazines made it possible to establish the effect of the substrate structure on the direction of the process and the selectivity of the reaction, as well as on the possibility of the formation of disubstitution products. The corresponding disulfonyl chloride was obtained only in the case of sulfonylchlorination of 1-(4-methoxyphenylpyridazin-3-yl)-3,5-dimethyl-1H-pyrazole at 100 °С for 10 h. In this case, the hydrogen atoms in position 3 of the benzene ring and position 4 of the pyrazole ring. In all other cases, monosubstitution products were obtained at the 4-position of the pyrazole ring. This is evidenced by the data of 1H NMR spectroscopy. On the basis of the obtained sulfonyl chlorides, the corresponding mono- and disulfonamides were synthesized. Convincing proof of the structure of all the obtained compounds has been carried out by a combination of mass spectrometry and NMR spectroscopy data.