New Chemicals Suppressing SARS-CoV-2 Replication in Cell Culture

Candidates to being inhibitors of the main protease (Mpro) of SARS-CoV-2 were selected from the database of Voronezh State University using molecular modeling. The database contained approximately 19,000 compounds represented by more than 41,000 ligand conformers. These ligands were docked into Mpro using the SOL docking program. For one thousand ligands with best values of the SOL score, the protein–ligand binding enthalpy was calculated by the PM7 quantum-chemical method with the COSMO solvent model. Using the SOL score and the calculated protein–ligand binding enthalpies, eighteen compounds were selected for the experiments. Several of these inhibitors suppressed the replication of the coronavirus in cell culture, and we used the best three among them in the search for chemical analogs. Selection among analogs using the same procedure followed by experiments led to identification of seven inhibitors of the SARS-CoV-2 replication in cell culture with EC50 values at the micromolar level. The identified inhibitors belong to three chemical classes. The three inhibitors, 4,4-dimethyldithioquinoline derivatives, inhibit SARS-CoV-2 replication in Vero E6 cell culture just as effectively as the best published non-covalent inhibitors, and show low cytotoxicity. These results open up a possibility to develop antiviral drugs against the SARS-CoV-2 coronavirus.     

Synthesis of Substituted Aminopyrimidines as Novel Promising Tyrosine Kinase Inhibitors

Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by...     

Three-Component Condencations of 3-Amino-1,2,4-triazoles,Methyl 3-(2-Cycloamino-4-methylpyrimidin-5-yl)-3-oxopropionoates,and a Series of C1 Synthons as a Convenient Approach to Pyrimidin-5-yl-1,2,4-triazolo[1,5-a]pyrimidines

Russian Journal of Organic Chemistry - A convenient synthetic approach to polysubstituted dihydrogenated or heteroaromatic 1,2,4-triazolo[1,5-a]pyrimidines derivatives containing at position 5 a...     

Synthesis of polyazaheterocycles containing linearly bound 1,2,4-thiadiazole using enaminones

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.     

New Aspects of the Reaction of Thioacetamide and N-Substituted Maleimides

N-Arylmaleimides are universal substrates for the synthesis of various heterocyclic compounds with a wide spectrum of biological activity. However, their reactions with thioacetamides have not been comprehensively studied. We studied the reactions of thioacetamide with N-arylmaleimides under various conditions. We established for the first time that three types of products: epithiopyrrolo[3,4-c]pyridines, pyrrolo[3,4-c]pyridines and 3,3′-thiobis(1-arylpyrrolidine-2,5-diones) can be obtained in different conditions. In all cases, two maleimide molecules are involved in the reaction. 3,3′-Thiobis(1-arylpyrrolidine-2,5-diones) are the major products when the reaction is conducted at boiling in acetic acid. When thioacetamide and N-arylmaleimide are kept in dioxane at 50 °C, epithiopyrrolo[3,4-c]pyridines can be isolated, which, when heated in dioxane, in acetic acid or in methanol in the presence of catalytic amounts of sodium methoxide, are converted into pyrrolo[3,4-c]pyridines by eliminating hydrogen sulfide. The reaction of thioacetamide and N-arylmaleimide in dioxane at boiling temperature with the portioned addition of N-arylmaleimide leads predominantly to the formation of pyrrolo[3,4-c]pyridines. The reaction of thioacetamide with N-alkylmaleimides under all the above conditions leads predominantly to the formation of the corresponding sulfides. The structure of the compounds obtained was characterized by a set of spectral analysis methods and X-ray diffraction (XRD) data.     

Crystal chemistry of clay minerals in bottom sediments of the Sea of Okhotsk as a paleoclimatic indicator

X-ray diffraction and infrared spectroscopy were used to study the mineral composition of bottom sediments of the Sea of Okhotsk with ages ranging from Holocene (10 My ago) to Pleistocene (10 to ～74 My ago). The concentrations of nonlayered minerals (quartz, plagioclase, carbonates, and biogenic silica) were determined from IR spectra, which made it possible to estimate the actual abundance of the clay component in test samples. Calibration curves used in the calculation were plots of the optical density in the maximum of the analytical absorption band of the analyzed component versus its concentration in the sample. These curves were constructed for standard mixtures of known compositions. The crystal-chemical parameters and quantitative ratios of clay minerals were elucidated by the computer simulation of X-ray diffraction profiles; clear correlations were found between these parameters and paleoclimatic changes. Our results show that the clay minerals from the bottom sediments of the Sea of Okhotsk can serve to search for paleoclimatic events in the North-Eastern Asia.