Sergey G. Krivokolysko

Inhibitors of tick-borne flavivirus reproduction from structure-based virtual screening.

Flaviviruses form a large family of enveloped viruses affecting millions of people over the world. To date, no specific therapy was suggested for the infected people, making the treatment exclusively symptomatic. Several attempts were performed earlier for the design of fusion inhibitors for mosquito-borne flaviviruses, whereas for the tick-borne flaviviruses such design had not been performed. We have constructed homology models of envelope glycoproteins of tick-transmitted flaviviruses with the detergent binding pocket in the open state. Molecular docking of substituted 1,4-dihydropyridines and pyrido[2,1-b][1,3,5]thiadiazines was made against these models, and 89 hits were selected for the in vitro experimental evaluation. Seventeen compounds showed significant inhibition against tick-borne encephalitis virus, Powassan virus, or Omsk hemorrhagic fever virus in the 50% plaque reduction test in PEK cells. These compounds identified through rational design are the first ones possessing reproduction inhibition activity against tick-borne flaviviruses.

Design and synthesis of pyrido[2,1-b][1,3,5]thiadiazine library via uncatalyzed Mannich-type reaction.

This Research Article describes the synthesis of an over 700-member library of (8R/8S)-3-R-8-aryl-6-oxo-3,4,7,8-tetrahydro-2H,6H-pyrido[2,1-b][1,3,5]thiadiazin-9-carbonitriles by uncatalyzed Mannich-type reaction of N-methylmorpholinium (4R/4S)-4-aryl-3-cyano-6-oxo-1,4,5,6-tetrahydropyridin-2-thiolates with a set of primary amines and excessive HCHO. The scope and limitations of the reaction were studied. Starting thiolates were obtained in yields of 53-82% by multicomponent reaction of aromatic aldehydes, cyanothioacetamide, 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrums acid), and N-methylmorpholine, followed by heterocyclization of the resulting Michael adducts.

Synthesis of partially hydrogenated 1,3,5-thiadiazines by Mannich reaction

n We offer a systematic and generalized review of literature data over the previous 10 years regarding the synthesis of monocyclic and condensed 1,3,5-thiadiazine derivatives under the conditions of Mannich reaction.

Aminomethylation of morpholinium and N-methylmorpholinium 3,5-dicyano-4,4-dimethyl-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates

nThe structure of reaction products obtained from 3,5-dicyano-4,4-dimethyl-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates, primary amines, and formaldehyde substantially depends on the nature of counter-ion (morpholinium or N-methylmorpholinium), as well as on the primary amine structure and the ratio of reactants. Aminomethylation of these thiolates with highly nucleophilic amines RCH2NH2 and excess formalin (2 equiv and more) produced 7-RCH2-9,9-dimethyl-2-oxo-4-thioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitrile salts, which gave the respective bispidines upon acidification. Performing this reaction with aromatic amines in the case of N-methylmorpholinium 3,5-dicyano-4,4-dimethyl-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolate led to analogous bispidines, while the morpholinium salt gave 3-aryl-8,8-dimethyl-7-[(morpholin-4-yl)methyl]-6-oxo-3,4,7,8-tetrahydro-2H,6H-pyrido[2,1-b][1,3,5]thiadiazine-7,9-dicarbonitriles. The treatment of thiolates with 1 equiv of НСНО and 1 equiv of RCH2NH2 led to 7-RCH2-4-amino-9,9-dimethyl-2-oxo-6-thioxo-3,7-diazabicyclo[3.3.1]non-3-ene-1-carbonitriles. The molecular and crystal structures of key compounds were studied in detail by X-ray structural analysis.

Dihydro-2H-thiopyran-3(4H)-one-1,1-dioxide – a versatile building block for the synthesis of new thiopyran-based heterocyclic systems

Three series of new cyclic sulfones have been prepared by a one-pot multi-component reaction (MCR) starting from the readily available dihydro-2H-thiopyran-3(4H)-one-1,1-dioxide. The in silico screening of the synthesized compounds revealed their high anti-inflammatory, antiarthritic, antiasthmatic and antiallergic potential coupled with the strong probability levels of cystinyl aminopeptidase inhibition. The key structures were confirmed by 2D NMR techniques.

Synthesis of thiazolo[3,2-a]pyridines via an unusual Mannich-type cyclization

ABSTRACT The Mannich-type reaction of N-methylmorpholinium 4-aryl-3-cyano-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates with 3-(1,3-benzodioxol-5-yl)-2-methylpropanal (ocean propanal) and p-toluidine afforded 7-aryl-2-(1,3-benzodioxol-5-ylmethyl)-2-methyl-3-[(4-methylphenyl)amino]-5-oxo-2,3,6,7-tetrahydro-5H-thiazolo[3,2-a]pyridine-8-carbonitriles in modest (25–46%) yields. The structure of the key compound was confirmed by X-ray crystal structure analysis. GRAPHICAL ABSTRACT

Synthesis, structure, and reactions of (4-aryl-3-cyano-6-oxopiperidin-2-ylidene)malononitriles

n The reaction of aromatic aldehydes with Meldrums acid and malononitrile dimer in the presence of triethylamine led to the formation of (4-aryl-3-cyano-6-oxo-1,4,5,6-tetrahydropyridin-2-yl)malononitrile triethylammonium salts, which were converted upon acidification to (4-aryl-3-cyano-6-oxopiperidin-2-ylidene)malononitriles. The reaction of these compounds with thioglycolic acid anilide was observed to produce derivatives of 1,6-naphthyridine or thieno[2,3-h][1,6]naphthyridine, depending on the conditions. Structures of (3-cyano-6-oxo-4-phenylpiperidin-2-ylidene)malononitrile and its triethylammonium salt were studied by X-ray structural analysis.

Synthesis of Pyrido[1,2-a][1,3,5]Triazine Derivatives by Aminomethylation of 6-Amino-4-Aryl-2-Oxo-1,2-Dihydropyridine-3,5-Dicarbonitriles

The aminomethylation of 6-amino-4-aryl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitriles by treatment with primary amines and an excess of formaldehyde resulted in the formation of 3-R-8-aryl-6-oxo-1,3,4,6-tetrahydro-2Н-pyrido[1,2-а][1,3,5]triazine-7,9-dicarbonitriles. The structure of 6-oxo-3,8-di-phenyl-1,3,4,6-tetrahydro-2Н-pyrido[1,2-а][1,3,5]triazine-7,9-dicarbonitrile was investigated by X-ray structural analysis.

A New Approach to the Synthesis of Functional Derivatives of 3-(4-Pyridinyl)-1H-indole and 4-(1H-Indol-3-yl)thieno[2,3-b]pyridine

Sequential reaction of indole-3-carbaldehyde with cyanothioacetamide and KOH led to the formation of potassium 6-amino-4-(1H-indol-3-yl)-3,5-dicyanopyridine-2-thiolate. S-Alkylation of the latter afforded new functional derivatives of 3-(pyridine-4-yl)-1H-indole and 4-(1H-indol-3-yl)-thieno[2,3-b]pyridine.

Probing chemical space of tick‐borne encephalitis virus reproduction inhibitors with organoselenium compounds

Tick‐borne encephalitis virus (TBEV), a member of the genus Flavivirus, is the leading cause of arboviral neuroinfections in Europe. Only a few classes of the nucleoside and non‐nucleoside inhibitors were investigated against TBEV reproduction. Paving the way to previously unexplored areas of anti‐TBEV chemical space, we assessed the inhibition of TBEV reproduction in the plaque reduction assay by various compounds derived from cyanothioacetamide and cyanoselenoacetamide. Compounds from seven classes, including 4‐(alkylthio)‐2‐aryl‐3‐azaspiro[5.5]undec‐4‐ene‐1,1,5‐tricarbonitriles, 3‐arylamino‐2‐(selenazol‐2‐yl)acrylonitriles, ethyl 6‐(alkylseleno)‐5‐cyano‐2‐oxo‐1,2‐dihydropyridine‐3‐carboxylates, 6‐(alkylseleno)‐2‐oxo‐1,4,5,6‐tetrahydropyridine‐3‐carbonitriles, 2‐(alkylseleno)‐5‐oxo‐1,4,5,6,7,8‐hexahydroquinoline‐3‐carbonitriles, 8‐selenoxo‐3,5,7,11‐tetraazatricyclo[7.3.1.02,7]tridec‐2‐ene‐1,9‐dicarbonitriles, and selenolo[2,3‐b]quinolines, inhibited TBEV reproduction with EC50 values in the micromolar range while showing moderate cytotoxicity and no inhibition of enterovirus reproduction. Thus, new scaffolds with promising anti‐TBEV activity were found.