Russian Journal of Organic Chemistry最新文献

The behavior of a representative series of previously unknown 2-(alkylsulfanyl)pyridines, prepared starting from isothiocyanates, acetylene or allene carbanions, and alkylating agents via the intermediate formation and aromatization of 6-(alkylsulfanyl)-2,3-dihydropyridines, under electron ionization (70 eV) has been studied for the first time. All studied compounds formed stable molecular ions (M^+•, I_rel 21–100%). In most cases, the primary fragmentation pathway involved the loss of a hydrogen atom to give an [M – H]⁺ ion. Moreover, for 3-ary(hetaryl)-substituted pyridines, except for 6-(vinyloxymethyl)-2-(methylsulfanyl)-3-phenylpyridine and 6-methyl-2-(methylsulfanyl)pyridine, this is the main fragmentation pathway. The other significant primary fragmentation pathways of the molecular ions of the synthesized compounds were associated with the fragmentation of the alkylsulfanyl group to form [M – Me]⁺, [M – SH]⁺, [M – SCH]⁺, [M – SCH₂]^+•, [M – SMe]⁺, or [M – SEt]⁺ ions, depending on the nature and position of substituents in the pyridine ring. The introduction of a substituent (R, OR, SR), where R = Alk > Me, into the pyridine molecule gives rise to a competing fragmentation pathway for the M^+• ion, associated with the loss of an alkene molecule. The fragmentation pathways of the molecular ions of 2-(alkylsulfanyl)pyridines with an OR substituent in the pyridine ring depends on whether the charge is localized on the oxygen or the sulfur atom. In the case of longer chain alkyl substituents (R = Bu, MeCHOEt), McLafferty rearrangement occurs along with simple bond cleavage. The fragment ions formed from the molecular ions of 3-aryl(hetaryl)pyridines are stabilized through the rearrangement into polycyclic aromatic structures that undergo little further fragmentation.

A series of p-substituted tetrafluoroaldehydes and ketones were obtained by the reaction of pentafluoroacetophenone and pentafluorobenzaldehyde with an excess of 4,4'-thiobisthiophenol, of 4,4'-thiobisphenol, and tert-butylthiophenol. The use of a double excess of pentafluoroacetophenone and pentafluorobenzaldehyde with respect to 4,4'-thiobisthiophenol and of 4,4'-thiobisphenol leads to the formation of bisoctafluoroaldehydes and ketones in high yields. Starting from mono- and disubstituted aldehydes and ketones, novel mono- and bispolyfluorochalcones containing aryl ether and thioether moieties, suitable for further modification, were synthesized.

A novel and efficient method for the synthesis of 2,4,5-trisubstituted imidazoles has been developed using MCM-41-supported sulfated zirconia (S-Zr/MCM-41) as a heterogeneous catalyst. The approach involves a one-pot, thee-component reaction between benzoin, aromatic aldehydes, and ammonium acetate as the nitrogen source. MCM-41-supported ZrO₂ was synthesized and subsequently modified by sulfate impregnation. The prepared catalyst was thoroughly characterized by IR spectroscopy, XRD, SEM-EDX, TEM, and TGA analyses. The synthesis was performed in ethanol under reflux at 80°C using the catalyst, leading to the formation of corresponding 2,4,5-triaryl-1H-imidazoles in excellent yields. Reaction conditions were further optimized by varying catalyst loading and solvent choice. Remarkably high product yields, ranging from 90–96%, were achieved within 40 min.

The mechanism of the thermal isomerization reactions of ortho-, meta-, and para-difluorobenzenes was established by DFT/B3LYP/6-31G (d) calculations. It was shown the rate-limiting step of these processes involve the dearomatization of difluorobenzenes to form benzvalene intermediates.

The oxidation of N-tosyl-, N-benzoyl-, and N-pivaloyl-2-(cycloalk-1-en-1-yl)anilines with ozone followed by the reduction of the ozonation products with dimethyl sulfide in methylene chloride or hydroxylamine hydrochloride in isopropanol or methаnol was studied. The oxidation of N-tosylates in CH₂Cl₂ followed by treatment with Me₂S results in the exclusive formation of ketoaldehydes, whereas the reduction of the ozonation products in alcohols under the action of hydroxylamine hydrochloride yields acids and their esters in various ratios. The reduction of the ozonation products of 2-(2-cyclohex-1-en-1-yl-6-methylphenyl)-1H-isoindole-1,3(2H)-dione in MeOH under the action of hydroxylamine hydrochloride gives methyl 6-[2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-3-methylphenyl]-6-oxohexanoate as a single isolated product. The oxidation of N-[2-(6-methoxycyclohex-1-en-1-yl)-6-methylphenyl]-4-methylbenzenesulfonamide with ozone followed by treatment of the reaction mixture with hydroxylamine hydrochloride leads to methyl 5-methoxy-6-(3-methyl-2-{[(4-methylphenyl)sulfonyl]amino}phenyl)-6-oxohexanoate and N-{2-[6-(hydroxyimino)-2-methoxyhexanoyl]-6-methylphenyl}-4-methylbenzenesulfonamide in a 10 : 7 ratio. The oxime is formed as 1 : 2 syn/anti mixture, treatment, upon treatment with 2 equiv of methanesulfonyl chloride in triethylamine, is converted into the axial syn/anti atropisomers of N-[2-(5-cyano-2-methoxypentanoyl)-6-methylphenyl]-4-methyl-N-(methylsulfonyl)benzenesulfonamide in a 8 : 1 ratio, but their assignment to specific isomers remains unclear.

A series of three fluorobenzylidene-1,2,4-triazol-3-one derivatives―(E)-4-[(2-fluorobenzylidene)amino]- (1), (E)-4-[(3-fluorobenzylidene)amino]- (2), and (E)-4-[(4-fluorobenzylidene)amino]-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (3)―were synthesized and characterized by FTIR and ¹H and ¹³C NMR spectroscopy. Of the three synthesized isomeric (E)-4-(fluorobenzylideneamino)-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one derivatives, isomers 1 and 2 are novel compounds, and compound 3 is previously known. A theoretical study was performed using the DFT/B3LYP/6–311++G(d,p) method. The molecular structures of compounds 1–3 were optimized, and their structural parameters were determined. Experimental FT-IR and NMR data were compared with calculated values, which confirmed the molecular structures and supported the experimental findings. The antibacterial and leishmaniacidal activities of compounds 1–3 were evaluated by the microdilution assay. Streptococcus pneumoniae was the most susceptible bacterium, while compound 2 was less effective against the tested bacteria than the other derivatives. Molecular docking analysis identified key molecular interactions responsible for the antileishmanial activity of compound 1, demonstrating a high binding affinity for Trypanothione reductase (TRe).

A series of novel pyrazole–oxazolidine–morpholine hybrids―4-[4-(5-{[1-phenyl-3-(R-phenyl)-1H-pyrazol-4-yl]methyleneamino}methyl)-2-oxo-oxazolidin-3-yl)phenyl]morpholin-3-ones―were synthesized via the Vilsmeier–Haack reaction and screened for antimicrobial activity against Gram+ve (S. aureus, S. pyrogens) and Gram–ve (E. coli, P. aeruginosa) bacterial and fungal (C. albicans, A. clavatus, and A. niger) strains. All the products showed moderate antimicrobial activities, with the largest zones of inhibition showed by the derivatives with R = 3-Br and 4-Me. Molecular docking of the synthesized hybrids against a series of bacterial (PDB ID: 1JIJ, PDB ID: 4ROT, PDB ID: 1KZN, and PDB ID: 4JVI) and fungal (PDB ID: 5C5G, PDB ID: 1IYL, PDB ID: 1UKC) protein targets to assess their inhibitory potential. The results predicted that (E)-4-[4-(5-{[3-(bromophenyl)-1-phenyl-1H-pyrazol-4-yl]methyleneamino}methyl)-2-oxo-oxazolidin-3-yl)phenyl]morpholin-3-one and its 3-(4-methylphenyl) analog may exhibit antimicrobial activity and deserve further study as promising candidates for medical applications.

4-Alkyl-5-aryl(hetaryl)-substituted 2-(5-hydroxymethylfuran-2-yl)-1H-imidazol-1-ols were synthesized by the reaction of alkylaromatic 2-(hydroxyamino)propan-1-one oximes with 5-(hydroxymethyl)furan-2-carbaldehyde.

A procedure has been proposed for the synthesis of pyridine and quinoline Schiff bases from the corresponding aldehydes and amines, which afforded the target products in more than 85% yield. Thermal decomposition pathways of the synthesized compounds have been identified by GC/MS and TG/DSC-MS analysis. They involve elimination of the hydrocarbon substituent from the imine fragment or the entire azomethine group with the formation of cationic 3-phenylpyridine and 6-substituted quinoline species. Cyclic voltammetric study of the title compounds has shown that their electrochemical reduction/oxidation is an ir­reversible process leading to fragmentation of the substrate molecules.

The carbonylation of perfluorinated 3-arylpropenes ArCF₂CF=CF₂ (Ar = C₆F₅, 3-CF₃C₆F₄) in SbF₅ under atmospheric CO pressure at room temperature, followed by treatment of the reaction mixture with water or methanol, afforded (Z)-perfluoro-2-arylbut-2-enoic acids or their methyl esters, respectively. In contrast, perfluoro-2-phenylpropene failed to undergo carbonylation under similar conditions. Perfluorinated 3-methyl-1H-indene and 1-methylidene- and 1-ethylideneindanes in antimony pentafluoride added two carbon monoxide molecules, and the subsequent treatment of the reaction mixture with methanol gave dimethyl perfluoro-1-alkyl-1H-indene-1,3-dicarboxylate as the major carbonylation product.