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An easy, one-step approach to fluorescent aminomaleimides possessing a build-in linker handle is reported.

Background: Hepatoprotectors, currently used in clinical practice, often show low efficacy. One of the promising goals in the therapy of liver diseases is the targeted synthesis of smallmolecule drugs with hepatoprotective activity. Some heterocycles, such as 1,4-dihydropyridines, are proven to be good hepatoprotectors. Objective: This study aimed to prepare and investigate the hepatoprotective effects of some dihydro- and tetrahydro pyridines using the experimental rat model of tetrachloromethane (CCl4)- induced acute liver damage. Methods: Several 1,4-dihydropyridines and 1,2,3,4-tetrahydropyridines were synthesized by the reaction of cyanothioacetamide with carbonyl compounds and active methylene compounds, such as Meldrum’s acid, ethyl cyanoacetate or β-keto esters, followed by S-alkylation of intermediate pyridine-2-thiolates. In silico prediction studies were performed to explore the possible protein targets. Using virtual bioscreening tools, we selected the six most promising compounds from the library of new partially saturated pyridines. Six novel compounds were characterized by IR, 1H, 13C DEPTQ NMR spectroscopy, 2D NMR experiments (1H–13C HSQC, 1H–13C HMBC), HRMS (ESI), and elemental analysis. The hepatoprotective effects were studied in vivo on eighty white rats with CCl4-induced liver damage. Biochemical studies, including thymol turbidity test and measurements of levels of bilirubin, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase in the blood of rats, were performed. Results: Five of six studied compounds showed a good hepatoprotective effect on a rat model of tetrachloromethane (CCl4)-induced acute hepatitis. The blood of rats in the experimental groups revealed significantly lower levels of total bilirubin, alanine aminotransferases, aspartate aminotransferases, thymol turbidity and alkaline phosphatase compared to the control group of rats with acute toxic tetrachloromethane hepatitis. Conclusion: Our results suggests that compound, (benzyl 4-(4-chlorophenyl)-5-cyano-6-({2-[(3,4- dimethylphenyl)amino]-2-oxoethyl}thio)-2-methyl-1,4-dihydropyridine-3-carboxylate), can be considered as candidate for further preclinical studies. Moreover, as per our knowledge, this is the first report on the hepatoprotective effects of the 1,2,3,4-tetrahydropyridine series.

trans-2-Amino-4-aryl-5-benzoyl-4,5-dihydrothiophene-3-carbonitriles were prepared either by the reaction of 3-aryl-2-cyanothioacrylamides with α-thiocyanatoacetophenone or by the Michael-type addition of cyanothioacetamide to α-bromochalcones followed by intramolecular cyclization. The mechanism of the first reaction was studied using high-level quantum chemical calculations. Density functional theory (DFT) studies were carried out to determine the mechanism of the first reaction. A new approach toward the construction of the thieno[2,3-d]pyrimidine core system was demonstrated by the reaction of the prepared dihydrothiophenes with HCHO and RNH2 under noncatalyzed Mannich conditions.

The Michael addition reaction between dithiomalondianilide (N,N′-diphenyldithiomalondiamide) and arylmethylidene Meldrum’s acids, accompanied by subsequent heterocyclization, was investigated along with factors affecting the mixture composition of the obtained products. The plausible mechanism includes the formation of stable Michael adducts which, under the studied conditions, undergo further transformations to yield corresponding N-methylmorpholinium 4-aryl-6-oxo-3-(N-phenylthio-carbamoyl)-1,4,5,6-tetrahydropyridin-2-thiolates and their oxidation derivatives, 4,5-dihydro-3H-[1,2]dithiolo[3,4-b]pyridin-6(7H)-ones. The structure of one such product, N-methylmorpholinium 2,2-dimethyl-5-(1-(2-nitrophenyl)-3-(phenylamino)-2-(N-phenylthiocarbamoyl)-3-thioxopropyl)-4-oxo-4H-1,3-dioxin-6-olate, was confirmed via X-ray crystallography.

The Michael addition reaction between dithiomalondianilide (N,N′-diphenyldithiomalondiamide) and arylmethylidene Meldrum’s acids, accompanied by subsequent heterocyclization, was investigated along with factors affecting the mixture composition of the obtained products. The plausible mechanism includes the formation of stable Michael adducts which, under the studied conditions, undergo further transformations to yield corresponding N-methylmorpholinium 4-aryl-6-oxo-3-(N-phenylthio-carbamoyl)-1,4,5,6-tetrahydropyridin-2-thiolates and their oxidation derivatives, 4,5-dihydro-3H-[1,2]dithiolo[3,4-b]pyridin-6(7H)-ones. The structure of one such product, N-methylmorpholinium 2,2-dimethyl-5-(1-(2-nitrophenyl)-3-(phenylamino)-2-(N-phenylthiocarbamoyl)-3-thioxopropyl)-4-oxo-4H-1,3-dioxin-6-olate, was confirmed via X-ray crystallography.

Unusual cascade transformation was developed involving microwave assisted electrocyclic cyclization of aci (alkylideneazinic acid) forms of nitrovinylindoles acting as heterotrienes. Subsequent one-pot reduction allowed for efficient access to β-carbolines, including several natural products, alkaloids norharmane, harmane and eudistomin N.

Microwave-assisted reaction between 2-(3-oxoindolin-2-yl)-2-phenylacetonitriles andbenzene-1,2-diamines leads to the high-yielding formation of the corresponding quinoxalines as sole, easily isolaable products. The featured transformation involves unusual extrusion of phenylacetonitrile molecule and could be performed in a short sequence starting from commonly available indoles and nitroolefins.

Noncatalyzed, regio- and stereoselective hypochlorite oxidation of 3-aminothieno[2,3-b]pyridine-2-carboxamides is presented. Unexpectedly, the oxidation proceeded by different mechanistic pathways, and different products were formed, depending on the nature of solvents used. A possible mechanism, the structure of products, kinetics and dynamics of intramolecular processes, and biological activity of products are discussed.

Indolizines and pyrazolo[1,5-a]pyridines were prepared via [3 + 2]-cycloaddition of pyridinium ylides to 1-chloro-2-nitrostyrenes. The synthesized molecules were evaluated for antiproliferative activities against a BE(2)-C neuroblastoma cell line with several compounds decreasing the viability of cancer cells. Indolizine 9db showed higher potency than that of all-trans-retinoic acid, an approved cancer drug. Mechanistically, it was found to inhibit tubulin polymerization and it is thus proposed that the discovered chemistry can be exploited for the development of novel microtubule-targeting anticancer agents.

A highly efficient one-pot procedure combining conjugate addition of Grignard reagents to (2-nitroalkenyl)indoles and sub-sequent Bronsted acid-assisted spirocyclization allowed for preparation of 4′H-spiro[indole-3,5′-isoxazoles] in a diastereomerically selective fashion. Utilization of alkyl Grignard reagents provided an easy access to 4′-alkylsubstituted derivatives hardly available by other means.

A convenient preparative method is developed allowing for expeditious assembly of 3,5-diarylsubstituted 5-hydroxy-1,5-dihydro-2H-pyrrol-2-ones from routinely available inexpensive synthetic precursors. These compounds could not be prepared via the previously known protocols, as 2-aminofuran derivatives were produced instead.

The sequential reaction of furfural with cyclic secondary amines and further with benzaldehyde and cyanoacetates affords new 2,4-dicyano-8-(R2N)-6-oxo-3-phenylbicyclo[3.2.1]-octane-2,4-dicarboxylates as rac-(1R,2R,3R,4S,5S,8R)-diastereomers. The structures of the reaction products were determined by X-ray diffraction.

An efficient and straightforward Bronsted-acid mediated cascade process was developed, involving cyclization of readily available β-ketonitriles into 2-aminofurans, and their subsequent recyclizati...

Unusual reaction proceeding via the electrophilic activation of nitroalkanes in the presence of polyphosphoric acid has been discovered. Subsequent nucleophilic attack with semicarbazides or thiosemicarbazides allows to access 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles, respectively.

Straightforward method for the synthesis of pyrrolo[1,2-b]cinnolines starting from 2-nitrobenzaldehydes and 2-methylfurans has been elaborated. The key steps of the process are oxidative furan ring opening with diazonium cation and intramolecular alkylation of azo group of the resulted cinnoline with secondary allyl alcohol.

Coordination compound of Eu(III) with glycine (Gly) with the composition EuCl3·3Gly·3H2O is synthesized. The obtained XRD data testify that the coordination compound is characterized by a bidentate coordination of glycine via the carboxyl group without the participation of the amino group. The structure is composed of polymer chains where two of three coordinating carboxyl groups are bridging groups connecting neighboring europium(III) atoms. The polymer chains are arranged in the form of parallel layers containing outer-sphere chlorine atoms between them. The structural formula [Eu(Gly)3(H2O)3]Cl3 of the complex is determined from XRD data which agree with IR spectroscopy, elemental and thermal analysis, and luminescence spectroscopy data.

The reaction of N-substituted amides of 3-amino-4,6-diarylthieno[2,3-b]pyridine-2-carboxylic acids with ninhydrin in the presence of catalytic amounts of sulfuric acid gave 1′-spiro[indene-2,2′-pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine]-1,3,4′(3′H)-triones. Structure of a number of key compounds was studied using 2D NMR spectroscopy; the bioavailability parameters of the obtained compounds in silico were calculated. In a laboratory experiment, a moderate antidote effect was revealed with respect to the 2,4-D herbicide for one compound.

Terminal polychlorides of hyperbranched polyester polyol Boltorn H20 were synthesized. Subsequent treatment of the resultant polychlorides with absolute pyridine or triphenylphosphine led to the formation of products of varying degrees of functionalization, containing pyridinium or triphenylphosphonium moieties in terminal positions.

An original, facile, and highly efficient method for the preparation of 2-(3-oxoindolin-2-ylidene)acetonitriles from ortho-nitrochalcones is described. The featured transformation is a triggered Michael addition of the cyanide anion to the chalcone followed by a cascade cyclization mechanistically related to the Baeyer–Drewson reaction.

A facile and highly efficient method for the preparation of 2-(3-oxoindolin-2-ylidene)acetonitriles from 4-(2-aminophenyl)-4-oxo-2-phenylbutanenitriles is described. The featured transformation operates via nucleophilic intramolecular cyclization and involves oxidation of the aniline moiety. Overall, this modification allowed for the improvement of yields and expansion of the reaction scope.

The recently discovered [4+1]-spirocyclization of nitroalkenes to indoles provided a convenient new approach to 2-(1H-indol-2-yl)acetonitriles. However, this reaction was complicated by the formation of inert 3-(2-nitroethyl)-1H-indole byproducts. Herein, we offer a workaround this problem that allows for effective transformation of the unwanted byproducts into acetonitrile target molecules.

Nitroalkanes activated with polyphosphoric acid could serve as efficient electrophiles in reactions with amines and hydrazines, enabling various cascade transformations toward heterocyclic systems. This strategy was developed for an innovative synthetic protocol employing simultaneous or sequential annulation of two different heterocyclic cores, affording [1,2,4]triazolo[4,3-a]quinolines with 1,3,4-oxadiazole substituents.

The mechanistic rationale involving activation of nitroalkanes towards interaction with nucleophilic reagents in the presence of polyphosphoric acid (PPA) was re-evaluated. Could nitrile oxide moieties be formed during this process? This experiment demonstrates that at least in some cases this could happen, as generated nitrile oxides were successfully intercepted as adducts of [3 + 2] cycloadditions.

A new method for synthesizing 11H-indolo[3,2-c]quinolines by SnCl4-catalyzed intramolecular electrophilic amination of 2-arylindole-3-carbaldehyde O-acetyl oximes was developed.

The reaction of 3-pentylpentane-2,4-dione with cyanothioacetamide afforded 4,6-dimethyl-5-pentyl-2-thioxo-1,2-dihydropyridine-3-carbonitrile. Alkylation of the latter led to the formation of 2-alkylsulfanyl-4,6-dimethyl-5-pentylpyridine-3-carbonitriles or 3-amino-4,6-dimethyl-5-pentylthieno[2,3-b]pyridines, depending on the alkylating agent and reaction conditions. The structures of the key compounds were proved by 2D NMR spectroscopy and X-ray analysis. Biological activity of the synthesized compounds was evaluated in silico. Some compounds were experimentally found to stimulate growth of sunflower seedlings.

Synthetic approach toward indole derivatives bearing 2-nitroethyl group and polar azole moiety has been developed. This method involves conjugate addition of 1,3-dicarbonyl compounds to 3-(2-nitrovinyl)-1H-indoles followed by cyclocondensation with hydrazine or hydroxylamine to furnish pyrazole or isoxazole ring. Application of microwave activation allows to obtain the target indole derivatives in short time and avoid protection of indole nitrogen atom.

A new method for the synthesis of 6,7-dimethoxy-3,4-dihydroisoquinoline based on the reaction of 2-(3,4-dimethoxyphenyl)ethan-1-amine (homoveratrylamine) with aliphatic nitro compounds in polyphosphoric acid (PPA) was developed.

A novel one-pot method based on the sequence of the Fisher reaction between nitroacetophenone and phenylhydrazines, the reduction with metallic tin directly in polyphosphoric acid, and acylation has been developed for the synthesis of indoloquinolines. The obtained indolo-[3,2-c]quinolines are precursors of the analogs of isocryptolepine alkaloid.

A novel methodology for general and chemoselective preparation of non-symmetric 1,3,4-oxadiazoles is developed. This unusual reaction proceeds via polyphosphoric acid-assisted activation of nitroalkanes towards nucleophilic attack with acylhydrazides.

The reaction of 5-amino-3-(cyanomethyl)-1H-pyrazole-4-carbonitrile with 3-aryl-5-hydroxy-5- methyl-2,4-di(ethoxycarbonyl)cyclohexanones in acetic acid furnished previously unknown 4,5,6,7,8,9-hexahydropyrazolo[1,5-a]quinazoline derivatives.