Vol 93, No 12 (2023)

It was shown that phosphoric anhydride can be used for the synthesis of esters and amides of carboxylic acids when they react with compounds containing hydroxyl and primary amino groups. A new method was proposed for obtaining paracetamol. An example of the reverse reactivity of these nucleophilic centers located in para -aminophenol molecule was revealed.

The reaction of 4,6-dimethyl-2-thioxo-1,2-dihydropyridin-3-carbonitriles with K₃[Fe(CN)₆] in an alkaline medium led to the formation of a mixture of oxidation products: bis(3-cyanopyridin-2-yl)disulfides and potassium 3-cyano-4,6-dimethylpyridine-2-sulfonates. Structure of the compounds was confirmed by NMR, IR spectroscopy and high-resolution mass spectrometry data. According to the results of molecular docking, 2,2′-dithiobis(5-butyl-4,6-dimethylnicotinonitrile) exhibits affinity for the zinc finger binding site of the HIV-1 p7 nucleocapsid protein.

A three-stage method was proposed for the synthesis of (1 S )-(+)-camphor-10-sulfonic acid, (+)-ketopinic and (-)-camphanic acids esters containing a saturated nitrogen-containing heterocycle. It was found that (1 S )-(+)camphor-10-sulfonic acid esters undergo destruction with elimination of the sulfonic acid group in substitution reactions involving nitrogen-containing heterocycles. Esters of (+)-ketopinic and (-)-camphanic acids were formed during the proposed synthetic route, but undergo transesterification under column chromatography conditions. Quantum chemical calculations showed that the destruction of the ester bond in the case of (+)-ketopinic and (-)-camphanic acids requires less energy than the breaking of a similar bond in (-)-borneol esters. It was revealed that the internal bond strength index (IBSI) for the alkyl C-O bond in (-)-borneol esters is higher than in (+)-ketopinic and (-)-camphanic acid esters. Antiviral properties against the H1N1 influenza virus were studied for derivatives of (+)-ketopinic and (-)-camphanic acids.

A series of 6-amino-4-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitriles was synthesized, further reaction of which with dimethyl chloroethynylphosphonate yielded a series of new dimethyl (8-cyano-7-aryl-5-thioxo-5,6-dihydroimidazo[1,2- c ]pyrimidin-2-yl)phosphonates.

Alkaline hydrolysis of ethyl 4-(diethoxyphosphoryl)-4,7-dihydro-5 Н -thiopyrano[3,4- b ]furan-5-carboxylate proceeded selectively at the ester group. The acid obtained formed the corresponding acid chloride when treated with thionyl chloride. The acid chloride was used for acylation of glycine, α- and β-alanine esters. Under the conditions of phase transfer catalysis this acid chloride formed acyl azide which under mild conditions undergoes rearrangement to isocyanate. The latter reacted with primary amines to give ureas, and with the amino acid esters in forms ureidoesters. Reducing of acid chloride with sodium borohydride led to the corresponding alcohol. It was converted to chloride which in the reactions with sodium azide and iodide gives usual substitution products. When treated with potassium thiocyanate it formed thiocyanate. Iodide in the reaction with triethyl phosphite gave the corresponding phosphonate. Oxidation of alcohols with Collins reagent and acetic acid-DMSO system was studied.

A new method was proposed for the preparation of diphenylphosphinylformic acid hydrazide based on the reaction of phosphine oxide and trimethylchlorosilane in the presence of a tertiary amine, followed by interaction with chloroformic acid ester and then hydrazine hydrate. The hydrazide moiety was modified into a thiosemicarbazide moiety by reacting diphenylphosphinylformic acid hydrazide with organic isothiocyanates. It was found that in an aqueous alkaline medium, thiosemicarbazides do not heterocyclize to 1,2,4-triazole-3-thiones, as expected. As a result of the rupture of the P-C bond, diphenylphosphinic acid and a 5-thioxo-1,2,4-triazolidin-3-one were formed.

Radical copolymerization was used to synthesize copolymers of coumarin and N -vinylpyrrolidone with molecular masses and compositions varying over wide limits. Molecular and hydrodynamic characteristics of the prepared copolymers and their dependence on the synthesis conditions were studied by dynamic and static light scattering.

The stability constants of triply charged lanthanide ions complexes with citric acid of 1:2 stoichiometry weremeasured by potentiometric titration in a wide pH range, and the relationship between the constants and the lanthanide type was analyzed. A mathematical model for the equilibrium in studied solutions was proposed.