Vol 60, No 4 (2024)

This review covers the new synthetic methods for annealed maleimide derivatives, namely pyrrolo[3,4-b]-pyrrolo-4,6(1H,5H)-diones, 4H-thieno[2,3-c]-pyrrolo-4,6(5H)-diones, 4H-pyrrolo[3,4-d]thiazole-4,6(5H)-diones, 5H-pyrrolo-[3,4-b]pyridine-5,7(6H)-diones, 1H-pyrrolo-[3,4-c]pyridine-1,3(2H)-diones, and other related compounds. The publications for the last 10 years are considered, including the methods for de novo synthesis of the maleimide core and the ones which use N-substituted maleimide or halogen-substituted maleimide derivatives as the main precursor.

A series of new dimers of pyrimidine nucleoside analogues have been synthesized. The dimers are composed of two uracil or thymine fragments linked at N³ through a polymethylene bridge and bearing a β-D-ribofuranose residue linked to N¹ of the nucleobase through a 1,2,3-triazolylalkyl spacer. Biological screening revealed that some of the synthesized dimers are active against influenza A (H1N1) virus and coxsackievirus B3 with IC₅₀ values of 13 and 4.5 μM, respectively.

The rate constants of the Diels-Alder reaction of thiofluorenone with 9,10-dimethylanthracene in toluene in the temperature range 15–35°C have been determined. Activation enthalpy and entropy have been calculated. Using NMR spectroscopy, mass spectrometry, and elemental analysis, the structure of thiofluorenone‒9,10-dimethylanthracene adduct has been determined.

New polyfunctional compounds of the pinane series, 2-carboxy-3-thioacetate, 2-carboxy-3-sulfonyl chloride, and 2-carboxy-3-sulfonic acid that are promising intermediate products in organic synthesis, were synthesized for the first time by the reaction of S-(1S,2R,3S,5R)-(6,6-dimethyl-2-formylnorpinan-3-yl) thioacetate with chlorine dioxide. The major reaction pathway in nonpolar solvents involves oxidation of the aldehyde group to carboxy, whereas oxidation of the sulfur atom, followed by deacetylation, occurs in highly polar solvents. The effect of VO(acac)2 as catalyst on the reaction chemoselectivity in weakly polar diethyl ether was revealed.

The hydrolysis of rapeseed oil in sub- and supercritical water (T = 573–653 K, p = 30 MPa) has been studied using a batch setup. Unlike traditional hydrolysis, the hydrothermal process involves in situ change of the fatty acid composition as a result of the transformation of linoleic acid to oleic acid, and there is the possibility of selective isolation of the latter with a purity sufficient for its use for technical purposes without special purification. A stepwise mechanism of the hydrothermal process has been proposed on the basis of analysis of transformation products of individual linoleic acid.

The reaction of dibenzo[b, e][1,4]dioxin-2,3-dicarbonitrile with sodium butoxide in butanol followed by treatment with nitric acid gave 1H-benzo[5,6][1,4]dioxino[2,3-f]isoindole-1,3(2H)-dione. Its condensation with quinaldine leads to the formation of (E, Z)-3-(quinolin-2-ylmethylene)-2,3-dihydro-1H-benzo[5,6][1,4]dioxino[2,3-f]isoindol-1-one, which was treated with BF3‧Et2O in the presence of triethylamine in toluene to obtain a new unsymmetrical analog of BODIPY, (Z)-2-(difluoroboryl)-3-(quinolin-2-ylmethylene)-2,3-dihydro-1H-benzo[5,6][1,4]dioxino[2,3-f]isoindol-1-one. The complex exhibits a Stokes shift of 36 nm and a high relative fluorescence quantum yield (0.72). To support the experimental data, the results of DFT and TDDFT calculations are presented.

The article presents a method for the preparation of (1S,2S,3R,4R,5S)-methyl-3,5-di-O-benzyl-2-O-benzoyl-α-L-talofuranoside from (1S,2S,3R,4R,5S)-methyl-3,5-di-O-benzyl-1,2-O-isopropylidene-α-L-talofuranoside by successive treatment of the latter with a 20% solution of hydrochloric acid in aqueous methanol, followed by treatment with benzoyl chloride in dry pyridine. A promising use of methyl (1S,2S,3R,4R,5S)-3,5-di-O-benzyl-2-O-benzoyl-α-L-talofuranoside for the synthesis of new modified nucleosides after its acetylation has also been shown.

New derivatives of 2-oxo-2,5-dihydrofurans containing 4-oxothiazolidine ring were synthesized by the interaction of 2-oxo-2,5-dihydrofuran thiosemicarbazones with diethylacetylenedicarboxylate in absolute ethanol and with maleic anhydride in chloroform. The synthesized compounds were characterized by NMR spectroscopy and elemental analysis data.