Том 59, № 8 (2023)

To study the structure and dynamics of nitrogen-containing compounds, NMR parameters with directly involved nitrogen can provide valuable structure information. However, this information can only be obtained using¹⁵N-enriched compounds due to low natural abundance of ¹⁵N and extremely short relaxation of ¹⁴N nuclei. For synthesis of these compounds from ¹⁵N-ammonium salts, ¹⁵N-enriched benzamides often used as intermediates. In the present work, we study the dynamic structure of benzamide caused by two independent factors: hindered internal rotation of the NH₂ group around the C(O)-N bond and the amide group as a whole relative to the benzene ring. This deeper knowledge of mechanism and parameters of these processes in amides is important for meaningful interpretation and prediction of the biological activity of aromatic amides in living systems, the strength and conformation of its supramolecular complexes with lanthanide and actinide ions. Double enriched [²H₅, ¹⁵N]benzamide was synthesized to avoid unwanted superposition of intense aromatic multiplet on the amide signals in the ¹H NMR spectra. In the ¹H spectrum of this compound observed only intense signals of amide protons, which allowed accurate quantitative characterization of the parameters of the dynamic processes under study. The experimental data obtained is in good agreement with our results of simulation by quantum molecular dynamics techniques.

Reaction of 4,6-di- tert -butyl-3-nitrocyclohexa-3,5-diene-1,2-dione with secondary amines (piperidine, morpholine, 1-methylpiperazine) in isopropanol leads to a mixture of products formed as a result of parallel reactions of Michael addition and ANRORC. The compounds obtained were characterized by ¹H NMR, ¹³C NMR, IR spectroscopy, and elemental analysis. Molecular structure of 3-nitrocyclohexa-3-ene-1,2-dione and cyclopenta1,3-diene derivatives was established by X-ray diffraction analysis.

By four-component condensation of ethyl acetoacetate, phenylglyoxal hydrate, barbituric acid and primary amines, polysubstituted pyrroles containing a barbituric acid fragment were obtained. In some cases, minor products of three-component condensation of phenylglyoxal hydrate, barbituric acid and amines have been isolated.

A series of О,О-dialkyl((aryl(hydroxy)methyl)phosphonates 1-4 with various substituents at the phosphorus atom was obtained by the Abramov reaction. The structure of the isolated products was confirmed by a complex of physical research methods: NMR, IR spectroscopy, mass spectrometry, and X-ray diffraction analysis. All the obtained compounds demonstrated activity against strains of B. cereus and S. aureus bacteria.

By the interaction of hydrophosphoryl compounds of various structures with hexamethyldisilazane at 20°C and in the presence of ZnSO₄ and diethylamine, trimethylsilyl esters of acids of III-valent phosphorus were synthesized in high yields (89-94%). The reaction is completed in 4 hours, does not require the use of specially prepared solvents and an inert atmosphere, and can be proposed as a new synthetically useful and easy-to-perform method for the synthesis of trimethylsilyl esters of acids of III-valent phosphorus.

The interaction of 4,5-dichlorocyclopent-4-en-1,3-dione with 1,3,5-trimethoxybenzene under Friedel-Crafts reaction conditions along with the expected 5-(2,4,6-trimethoxyphenyl)-4-chlorocyclopent-4-ene-1,3-dione obtained disubstituted product - 3,4-bis-(2,4,6-trimethoxyphenyl)-2-chlorocyclopent-2-en-1-one.