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The simultaneous quantum-chemical and spectral investigations of the possible relaxation pathways in the excited state for the two α,ω-di-substituted polyenes were performed. Lengthening of the polymethine chain is accompanied by the considerable decreasing of the first electron transition and hence is manifested as the bathochromic shift of both absorption and fluorescence spectra; however, the nature of transition does not change. It is established that the considerable changes of the bond lengths in polymethine chain for both vinylogs in the excited state cause firstly the appearance of the fast component in short wavelengths spectral region; after relaxation, the intensity of the fast component decreases, and it disappears, but then the spectral band, shifted bathochromically, appears, so that its maximum coincide with the band maximum in the steady-state fluorescence maximum, what corresponds to the final symmetrical relaxation of bond lengths. The parallel quantum-chemical calculation shows that two highest levels are mainly formed by the donor levels of both terminal groups and hence twice occupied splitting levels. Upon excitation, one of the splitting MO (HOMO) becomes single occupied; this causes the molecule in the excited state to be unstable and could transform it to the unsymmetrical form. Such relaxation path is confirmed by the time-resolved spectra: the spectral band in both molecules, with the different polymethine chains, undergoes the subsequent bathochromical shifting.

A method for the synthesis of a series of new substituted 1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones was proposed based on the Diels–Alder type reaction of 4-methoxy-1,3-oxazoles with maleimide derivatives.

The binding affinity of model aromatic amino acids and heterocycles and their derivatives condensed with pyridine were investigated in silico and are presented in the framework of fragment-to-fragment approach. The presented model describes interaction between pharmacophores and biomolecules. Scrupulous data analysis shows that expansion of the π-electron system by heterocycles annelation causes the shifting up of high energy levels, while the appearance of new the dicoordinated nitrogen atom is accompanied by decreasing of the donor-acceptor properties. Density Functional Theory (DFT) wB97XD/6-31(d,p)/calculations of π-complexes of the heterocycles 1-3 with model fragments of aromatic amino acids, which were formed by π-stack interaction, show an increase in the stabilization energy of π-complexes during the moving from phenylalanine to tryptophan. DFT calculation of pharmacophore complexes with model proton-donor amino acid by the hydrogen bonding mechanism (H-B complex) shows that stabilization energy (DE) increases from monoheterocycles to their condensed derivatives. The expansion of the π-electron system by introducing phenyl radicals to the oxazole cycle as reported earlier [18] leads to a decrease in the stabilization energy of the [Pharm-BioM] complexes in comparison with the annelated oxazole by the pyridine cycle.

A potential of using nickel complexes with 1,3-dicarbonyl compounds for the transformation of heterocyclic aminonitriles into fused systems with a 4-aminopyridine core was evaluated. A possibility of introducing acidophobic groups into the molecules of fused compounds was shown.

We propose a new method for assembling the imidazo[2,1-b][1,3]thiazole system, based on the reaction of (2Z)-1,3-diaryl-4-bromobut-2-en-1-one derivatives with 2-aminothiazoles. The outcome of this reaction depends on the structure of the starting bromo ketone: when electron-withdrawing substituents are present in the structure of the ketone, a competing reaction occurs, which leads to the formation of 2,5-diarylfurans. Screening for antitumor activity has been performed in the case of 1-phenyl-2-(6-phenyl-5,6-dihydroimidazo[2,1-b]- thiazol-6-yl)ethanone and this compound has shown moderate ability to suppress the growth of kidney cancer cells, with a weaker effect on the cell lines of prostate cancer, colon cancer, and leukemia.

A convenient method was developed for the synthesis of novel isoquinolin-1(2H)-ones, 1-chloroisoquinolines, and 1-aminoisoquinolines with a heterocyclic substituent in position 3 via a recyclization of 3-hetarylisocoumarins with (NH4)2CO3. 1-Aminoisoquinolines were efficiently obtained from corresponding 1-chloro-3-hetarylisoquinolines (obtained by interaction of isoquinolin-1(2H)-ones with POCl3) and cyclic secondary amines (morpholine or 1-methylpiperazine). Literature data and preliminary results of biological assays allow to consider 1-amino-3-hetarylisoquinolines a promising family of anticancer compounds.

Background: Tuberculosis (TB) is an infection disease caused by Mycobacterium tuberculosis (Mtb) bacteria. One of the main causes of mortality from TB is the problem of Mtb resistance to known drugs. Objective: The goal of this work is to identify potent small molecule anti-TB agents by machine learning, synthesis and biological evaluation. Methods: The On-line Chemical Database and Modeling Environment (OCHEM) was used to build predictive machine learning models. Seven compounds were synthesized and tested in vitro for their antitubercular activity against H37Rv and resistant Mtb strains. Results: A set of predictive models was built with OCHEM based on a set of previously synthesized isoniazid (INH) derivatives containing a thiazole core and tested against Mtb. The predictive ability of the models was tested by a 5-fold cross-validation, and resulted in balanced accuracies (BA) of 61–78% for the binary classifiers. Test set validation showed that the models could be instrumental in predicting anti- TB activity with a reasonable accuracy (with BA = 67–79 %) within the applicability domain. Seven designed compounds were synthesized and demonstrated activity against both the H37Rv and multidrugresistant (MDR) Mtb strains resistant to rifampicin and isoniazid. According to the acute toxicity evaluation in Daphnia magna neonates, six compounds were classified as moderately toxic (LD50 in the range of 10−100 mg/L) and one as practically harmless (LD50 in the range of 100−1000 mg/L). Conclusion: The newly identified compounds may represent a starting point for further development of therapies against Mtb. The developed models are available online at OCHEM http://ochem.eu/article/11 1066 and can be used to virtually screen for potential compounds with anti-TB activity.

Anticancer activity of a series of polyfunctional substituted 1,3-thiazoles has been studied within the international scientific program “NCI-60 Human Tumor Cell Lines Screen”. Screening was performed in vitro on 60 cell lines of lungs, kidneys, CNS, ovaries, prostate, and breast cancer, epithelial cancer, leukemia, and melanoma. The most effective compounds were those with a piperazine substituent at C2 of the 1,3-thiazole cycle: 1-(4-((4-methylphenyl)-sulfonyl)-2-phenyl-1,3-thiazol-5-yl)piperazine (average lg GI50 = -5.87, lg TGI = -5.54, lg LC50 = -5.21), 1-(2-(3,5-dimethyl-1H-pyrazol-1-yl)-4-((4-methylpheyl)sulfonyl)-1,3-thiazol-5-yl)piperazine (average lg GI50 = -5.66, lg TGI = -5.26, lg LC50 = -4.83), and 1-(2,4-bis((4-methylphenyl)sulfonyl)-1,3-thiazol-5-yl)piperazine (average lg GI50 = -5.67, lg TGI = -5.21, lg LC5050 = -4.67).

Synthetic 6-substituted purine derivatives are known to exhibit diverse bioactivity. In this paper, a series of N-(9H-purin-6-yl)-1,2-oxazole-3-carboxamide derivatives were synthesized and evaluated in vitro against xanthine oxidase, an enzyme of purine catabolism. The introduction of aryl substituent at position 5 of the oxazole ring was found to increase the inhibition efficiency. Some of the inhibitors containing 5-substituted isoxazole and purine moieties were characterized by IC50 values in the nanomolar range. According to the kinetic data, the most active N-(9H-purin-6-yl)-5-(5,6,7,8-tetrahydronaphthalen-2-yl)-1,2-oxazole-3-carboxamide demonstrated a competitive type of inhibition with respect to the enzyme-substrate. Molecular docking was carried out to elucidate the mechanism of enzyme-inhibitor complex formation. The data obtained indicate that xanthine oxidase may be one of the possible targets for the bioactive purine carboxamides.

A versatile and efficient three-component cyclization of methyl 4-(o-hydroxyphenyl)-2,4-dioxobutanoates 1, N-substituted isatins 2, and primary amines 3 was explored to synthesize of 2H-spiro[chromeno[2,3-c]pyrrole-1,3'-indoline]-2',3,9-triones. We obtained a library of 122 derivatives with an indolin-2-one motif as an important structural fragment in natural alkaloids. This method is practical and useful strategy for constructing dihydrochromeno[2,3-c]pyrrole-3,9-diones. Most of the obtained products also have functional groups for easy and further diversification by classical reactions.

Method of quantitative estimation of the π-electron affinity for conjugated molecules, which is directly related to donor/acceptor properties is presented. The index φ0 is proposed, it is determine...

The possibilities of 2-amino-3,3-dichloroacrylonitrile (ADAN) used for the construction of macrocyclic structures such as cyclophanes with two oxazole fragments are investigated. For this purpose, bifunctional reagents were used in the classic ADAN transformation into 5-amino-4-cyanooxazoles (sequential treatment of ADAN with acyl chloride and a primary or secondary amine). As a result of the reaction of 2,2'‎-(1,2-phenylene)-diacetyl chloride with 2 eq of ADAN, a compound with two acrylonitrile fragments, 2,2' ‎- (1,2-phenylene)bis(N- (2,2-dichloro-1-cyanovinyl)acetamide), was obtained. In this substance, both ADAN residues can interact with amines and form oxazole cycles: for example, the treatment with an excess of dimethylamine produces 2,2'‎ - (1,2-phenylenebis(methylene))bis(5-(dimethylamino)oxazole-4-carbonitrile). The target macrocyclic structure was obtained by the interaction of 2,2'‎ - (1,2-phenylene)bis(N-(2,2-dichloro-1-cyanovinyl)acetamide) with butane-1,4-diamine, as a result the simultaneous forming of both oxazole rings and an aliphatic bridge connected with them was happened. At this stage, it was used a procedure, that is typical of the creation of macrocyclic structures based on polyfunctional reagents, — strong dilution (about 0.04 M). The molecule of the synthesized 6,11-diaza-1,5(2,5)-dioxazole-3(1,2)-benzenecycloundecaphan-14,54-dicarbonitrile has high spatial symmetry, which is confirmed by the presence of only one series of peaks in the 1H and 13C NMR spectra (for example, the butane-1,4-diamine fragment in the aliphatic part of the spectrum looks likes two triplets). The formation of a macrocyclic structure is evidenced by HPLC-MS data, as well as homo- and heteronuclear correlations in the NMR spectra. The proposed procedure for the synthesis of 6,11-diaza-1,5(2,5)-dioxazole-3(1,2)-benzenecycloundecaphan- 14,54-dicarbonitrile is based on the use of simple and inexpensive reagents, and the total yield of the target substance in two stages starting with the 2,2'‎ - (1,2-phenylene)diacetyl chloride, is 51 %.

The ability of fullerene to form stable π → π-complexes was studied by quantum-chemical methods and the fluorescence quenching of reference dye (thiochrome). The correlation between the theoretically calculated and experimentally obtained energy of the π → π-complexes was determined. The energy of the stack interaction between fullerene and some biological active compounds, derivatives of 1,3-oxazoles, containing donor/acceptor substituents was estimated.

This minireview highlights known methods for the synthesis of azachromones and azachromanones, including the earliest and the latest examples of their synthesis. Methods considered for constructing azachromone or azachromanone system include intramolecular heterocyclization, deprotection–cyclization, spirocyclization, cyclization–aromatization, Ullman-type O-arylation, and C–H activation of pyridine N-oxides.

Background: The incidence of invasive fungal infections caused by Candida spp. has increased continuously in recent decades, especially in populations of immunocompromised patients or individuals hospitalized with serious underlying diseases. Therefore, the goal of our study was the search for new potent Candida albicans inhibitors via the development of QSAR models that could speed up this search process. A number of the most promising 1,3-oxazol-4-yltriphenylphosphonium derivatives with predicted activities were synthesized and experimentally tested. Furthermore, the toxicity of the studied compounds was determined in vitro using acetylcholinesterase enzyme as a biological marker. Methods: The classification QSAR models were created using Random Forests (WEKA-RF), k-Nearest Neighbors and Associative Neural Networks methods and different combinations of descriptors on the Online Chemical Modeling Environment (OCHEM) platform. Аntifungal properties of the investigated compounds were performed using standard disk diffusion method. The enzyme inhibitory action of the compounds was determined by modified Ellman's method using acetylcholinesterase from the electric organ of Electrophorus electricus. Results: Three classification QSAR models were developed by the WEKA-RF, k-NN and ASNN methods using the ALogPS, E-State indices and Dragon v.7 descriptors. The predictive ability of the models was tested through cross-validation, giving a balanced accuracy BA = 80-91%. All compounds demonstrated good antifungal properties against Candida spp. and slight inhibition of the acetylcholinesterase activity. Conclusion: The high percentage of coincidence between the QSAR predictions and the experimental results confirmed the high predictive power of the developed QSAR models that can be applied as tools for finding new potential inhibitors against Candida spp. Furthermore, 1,3-oxazol-4- yl(triphenyl)phosphonium salts could be considered as promising candidates for the treatment of candidiasis and the disinfection of medical equipment.

Ten 5-functionalized derivatives of 1,3-oxazole-4-carboxylate and 1,3-oxazole-4-carbonitrile were synthesized and their antiviral activities against the human cytomegalovirus (HCMV) were evaluated in vitro. Bioassays showed that seven compounds exhibited considerably higher antiviral activity (EC50: 150 µM, and SI50 = 3125) towards the resistant isolate compared to standard drugs Cidofovir (EC50 = 0.10 µM, CC50: >30 µM and SI50

For the estimation of donor/acceptor character of conjugated heterocyclic compounds, the φ0 index is used. This parameter is determined by the relative positions of the frontier molecular orbital energy levels. It is shown that φ0 value of 0.5 means that the donor and acceptor properties in the conjugated molecule are balanced, while an increase of the index (φ0 > 0.5) corresponds to increasing of the donor strength, and, conversely, its lowered value (φ0 < 0.5) points to increased acceptor strength. In this work, a series of widely known heterocyclic compounds, as well as derivatives of oxazole and nucleobases are analyzed in detail. It is shown that change in φ0 index is connected to the biological activity. As an example, the influence of the conjugated substituents is studied and it is found that the oxazole derivatives with acceptor substituents inhibit cancer cells.

The quantum-chemical analysis of donor–acceptor properties of the conjugated heterocyclic compounds is performed. For quantitative estimation of donor/acceptor ability, the topological index φ0 is ...

Background: Substituted pyrimidine derivatives (non-nucleoside) are found to be associated with various biological activities. The various substituted pyrimidines are also having significant in vitro activity against different DNA and RNA viruses. The present study focuses on the anti-PV activity of new pyrimidines and their condensed derivatives. Methods: A series of novel pyrimidines and their condensed derivatives were synthesized and their structures were confirmed by spectral data. Their antiviral activities against poliovirus type 3 (PV-3) were evaluated in vitro. In cell culture, morphological changes observed in cells infected with polioviruses, including cell rounding and detachment from the substrate, are generally termed cytopathic effects (CPE). The effects of synthetic pyrimidines on PV amplification in a culture of the heteroploid cell line, Vero 76 (African green monkey kidney cells) were investigated. Results: Bioassays in vitro showed that one of seven synthesized compounds, 7-(Benzenesulfonyl)-5- benzyl-N-(prop-2-en-1-yl)-5H-pyrrolo[3,2-d]pyrimidin-4-amine, has potent antiviral activity against PV-3 (EC50 = 0.75 μM). The selectivity index of this compound is similar to that of pirodavir. Conclusion: The need for antiviral agents to treat PV-associated diseases remains great, but few options currently exist. Here we show that substituted pyrimidine derivatives are a promising structure class of chemical compounds for the development of antiviral drugs against PV infections.

Background: Due to the increase of multidrug-resistant microorganisms, the search for biologically active molecules does not stop. In the present study, we developed the effective QSAR model which allows a quick search of new potential Staphylococcus aureus inhibitors in the series of quaternary phosphonium salts. A number of the most promising 1,3-oxazol-4-yltriphenylphosphonium derivatives with predicted activities were synthesized and examined to confirm their antibacterial properties and the accuracy of the forecast. Furthermore, the toxicity of the investigated compounds was evaluated. Methods: The predictive QSAR model was developed using Artificial Neural Network approach. Antibacterial properties of the investigated compounds were performed using standard disk diffusion method. The toxicity of the compounds was determined in vivo using zebrafish (Danio rerio) and in vitro on acetylcholinesterase (AChE) enzyme as the test models. Results: The predictive ability of the regression model was tested by cross-validation, giving the cross-validated coefficient q2=0.82. Derivatives of 1,3-oxazol-4-yltriphenylphosphonium salts predicted as active were synthesized and screened for their antibacterial activities. All compounds demonstrated antibacterial activity according to the prediction. The toxicity tests indicated that all investigated samples were less toxic than well-known cationic surfactants. Conclusion: The most promising compound 2b exhibited strong antibacterial activity together with low toxicity and can be considered as a new efficient biocidal agent for future investigation. In addition, the proposed QSAR model can be used for predicting and designing novel potential S. aureus inhibitors among ionic liquids/salts.

Graphic abstract An efficient and practical synthetic procedure for libraries of diversified 1,2-dihydrochromeno[2,3-c]pyrrole-3,9-diones using a multicomponent process is presented. A convenient synthetic procedure for obtaining functionalized 3-(2-hydroxyphenyl)-4,5-dihydropyrrolo[3,4-c]pyrazol-6(1H)-ones via ring-opening strategy has also been developed. This protocol was found to be compatible with a wide range of substituents and paves the way for the practical synthesis of title compounds with a broad range of substituents under mild condition. The products can be easily isolated by crystallization without the use of chromatography. Supplementary Information The online version contains supplementary material available at 10.1007/s11030-021-10234-2.

QSAR analysis of a set of previously synthesized phosphonium ionic liquids (PILs) tested against Gram-negative multidrug-resistant clinical isolate Acinetobacter baumannii was done using the Online Chemical Modeling Environment (OCHEM). To overcome the problem of overfitting due to descriptor selection, fivefold cross-validation with variable selection in each step of the model development was applied. The predictive ability of the classification models was tested by cross-validation, giving balanced accuracies (BA) of 76%-82%. The validation of the models using an external test set proved that the models can be used to predict the activity of newly designed compounds with a reasonable accuracy within the applicability domain (BA = 83%-89%). The models were applied to screen a virtual chemical library with expected activity of compounds against MDR Acinetobacter baumannii. The eighteen most promising compounds were identified, synthesized, and tested. Biological testing of compounds was performed using the disk diffusion method in Mueller-Hinton agar. All tested molecules demonstrated high anti-A. baumannii activity and different toxicity levels. The developed classification SAR models are freely available online at http://ochem.eu/article/113921 and could be used by scientists for design of new more effective antibiotics.

In this series, six new 2-substituted 5-arylsulfonyl-1,3-oxazole-4-carbonitriles were synthesized and characterized by IR, 1H NMR, 13C NMR spectroscopy, elemental analysis and chromato-mass-spectrometry. The anticancer activities of the compounds were evaluated via single high dose (10−5M) against 60 cancer cell lines by the National Cancer Institute according to its own screening protocol. In the next phase, the compounds have been selected for five-dose assay. All synthesized compounds displayed growth inhibitory (GI50) and cytostatic activities (TGI) against the most sensitive cell lines at submicromolar (0.2–0.6 μM) and micromolar concentrations (1–3 μM), respectively. Cytotoxic activity (LC50) of these compounds, with the exception of 4d, against the most sensitive cell lines was also high (5–6 μM). All compounds exhibit high selectivity towards leukemia cell lines, and among them, 4e and 4f showed the best antiproliferative and cytostatic selectivity. Compounds 4c and 4f displayed considerable cytotoxic selectivity towards the renal and breast cancer subpanels. Our results provided evidence for anticancer activities of novel 2-substituted 5-arylsulfonyl-1,3-oxazole-4-carbonitriles which could be useful for developing new anticancer drugs. These substances could also be used as an excellent framework in anticancer research that may lead to discovery of potent antitumor agents.

Spectral properties of the series of cationic polymethine dyes containing conjugated chain of different length and 4-pyrylium terminal groups were studied in details. Besides, the steady-state long-wavelength fluorescence from the lowest excited state and the fluorescence from higher excited states were experimentally revealed. The steady-state fluorescence band from the lowest excited state is shifted bathochromically with lengthening of the polymethine chain, which is also reflected in the absorption shift. According to quantum-chemical modeling, the appearance of unconventional fluorescence, which suppresses Kasha’s rule, is associated with the different nature of the lowest excited states: the first and forth transitions are typical polymethine electron transitions involved only totally delocalized molecular orbitals (MOs), whereas the second and third transitions correspond to the electron jumping from the degenerated MOs localized only within the terminal groups (so called quasi-local MOs and hence quasi-local transitions). The forbidden transitions between the excited states of different types stimulate the fluorescence from the higher excited states.

Reaction of 2-chloro-N-(2,2-dichloro-1-cyanovinyl)acetamide with dimethylamine gave 5-(dimethylamino)-2-[(dimethylamino)methyl]-1,3-oxazole-4-carbonitrile, where aliphatic dimethylamino group was regioselectively alkylated with iodomethane. The resulting trimethylammonium salt reacted diastereoselectively with aromatic aldehydes to form new substituted 2-(oxiran-2-yl)-1,3-oxazoles.

The problem of designing new antitubercular drugs against multiple drug‐resistant tuberculosis (MDR‐TB) was addressed using advanced machine learning methods. As there are only few published measurements against MDR‐TB, we collected a large literature data set and developed models against the non‐resistant H37Rv strain. The predictive accuracy of these models had a coefficient of determination q2=.7–.8 (regression models) and balanced accuracies of about 80% (classification models) with cross‐validation and independent test sets. The models were applied to screen a virtual chemical library, which was designed to have MDR‐TB activity. The seven most promising compounds were identified, synthesized and tested. All of them showed activity against the H37Rv strain, and three molecules demonstrated activity against the MDR‐TB strain. The docking analysis indicated that the discovered molecules could bind enoyl reductase, InhA, which is required in mycobacterial cell wall development. The models are freely available online (http://ochem.eu/article/103868) and can be used to predict potential anti‐TB activity of new chemicals.

A preparative method for the synthesis of 1-alkyl-3-methyl-1,4-dihydropyrazolo[4,3-c]pyrazoles was developed. The alkylation of the obtained compounds with halocarboxylic acid esters was also investigated. A principal possibility of creating libraries of compounds based on pyrazolo[4,3-c]pyrazole derivatives was shown.

Reaction of methyl 2-aryl-5-(chlorosulfonyl)-1,3-oxazole-4-carboxylates with 1H-pyrazol-5-amines and 1H-1,2,4-triazol-5-amines proceeds with the participation of endocyclic aminoazole nitrogen atoms to yield products containing a primary amino group. Being treated by sodium hydride these products undergo a further transformation into the tricyclic compounds. It has been shown that the cyclocondensation pathway includes the Smiles rearrangement with extrusion of SO2 followed by the elimination of MeOH. This reaction sequence is a convenient approach to the synthesis of new annulated [1,3]oxazolo[5,4-d]pyrimidine derivatives.

H-Lithiation and Br-lithiation reactions of 1,3-thiazole were studied in order to obtain new thiazole derivatives. Four isomeric chloromethyl derivatives of 1,3-thiazole containing a protected aldehyde group like 2-(1,3-dioxolan-2-yl)-5-(chloromethyl)-1,3-thiazole, 5-(1,3-dioxolan-2-yl)-2-(chloromethyl)-1,3-thiazole, 4-(1,3-dioxolan-2-yl)-2-(chloromethyl)-1,3-thiazole, and 2-(1,3-dioxolan-2-yl)-4-(chloromethyl)-1,3-thiazole were synthesized. Their nucleophilic substitution reactions with dimethylamine and sodium methylthiolate were studied. New aldehydes of 1,3-thiazole series of low-molecular weight were obtained.

A series of new 5-amino-1H-imidazole-4-carbonitriles were synthesized based on substituted 3,3-di-amino-2-methylideneaminoprop-2-enenitriles.

Acylation and sulfonylation of substituted pyrazolo[3,4-d][1,2,3]triazin-4-ones, as well as reactions with acylating agents proceeding via destruction of the triazine ring are studied.

Background: Chemotherapeutic approaches to the control of HPV infection suffer from a lack of specificity. For most existing HPV inhibitors, the weak antiviral effects observed in cellular assays suggest that further improvements in selecting targets, in drug potency, and in bioavailability and cell uptake are required. Objective: To synthesize novel 1,3-oxazole derivatives and define their antiviral activities against the human papillomavirus (HPV) in vitro. Methods: Determination of transient replication of an HPV-11 in transfected HEK293 cells, and HPV-18 DNA amplification in an organotypic squamous epithelial raft culture of primary human keratinocytes (PHKs), and cytotoxicity assays were used. Results: Bioassays showed that the synthesized compounds 2, 4, 5, and 9 exhibited potent antiviral activity against low-risk HPV-11 (IC50 = 1.7–9.6 μM) in a transient DNA replication assay and exhibited low cytotoxicity in HEK293 cells compared to cidofovir (CDV), antiviral agent in clinical use. Selectivity indices of compounds 4 and 5 were 20–40 times greater than that of CDV. However, compounds 4 and 9 did not exhibit a significant antiviral effect against high-risk HPV-18 infections in organotypic epithelial raft cultures. Although prophylactic HPV vaccines are now available to protect against primary infections by the seven genotypes most commonly found in cervical, penile, anal and oro-pharyngeal cancers (HPV16, 18, 31, 33, 45, 52, and 58) and two genotypes (HPV6 and 11) that cause benign anogenital warts and laryngeal papillomas, they do not protect against infections by other HPV types. Moreover, individuals already infected with HPV will not benefit from the vaccines. Thus, the need for antiviral agents to treat HPV-associated diseases remains great, but few options currently exist. Conclusions: We show that substituted 1,3-oxazole derivatives are a promising structure class of chemical compounds for the development of antiviral drugs against HPV lesions.

Novel derivatives of 3,3-dichloroprop-2-enenitrile containing methylurea or phenylurea fragments have been synthesized. The obtained N-(2,2-dichloro-1-cyanoethenyl)-N′-methyl(phenyl)ureas undergo intramolecular cyclization in the presence of triethylamine to form 4-(dichloromethylidene)-5-imino-1-methyl (phenyl)imidazolidin-2-ones. Reactions of N-(2,2-dichloro-1-cyanoethenyl)-N′-methylurea with aliphatic amines have afforded 4-(alkylamino)-4-(dichloromethyl)-5-imino-1-methylimidazolidin-2-ones.

The interaction of available 2-methylsulfonyl-3-ethoxyacrylonitrile with amidine, their analogs, and aminoazoles containing amidine fragment, yielding earlier unknown 4-amino-5-methylsulfonylpyrimidines and their fused derivatives has been studied.

Readily available tetrachloro-2-aza-1,3-butadienes enter into directed cyclocondensation reaction with N-phenyl-1,2-cyclopentanediamine which leads to regioselective cyclopentane annulation by the 1,3,5-triazepine. The formation of the 1,3,5-triazepine derivatives was confirmed proved by 1H- and 13C-NMR spectral study, elemental analysis and, in one case, single-crystal x-ray crystallographic study.

Reactions of 1-acylamino-2,2-dichloroacrylonitriles, diethyl 1-acylamino-2,2,2-trichloroethyl-phosphonates and 1-acylamino-2,2-dichloroethenylphosphonium salts with natural alkaloid cytisine have been studied. A series of novel multifunctional cytisine derivatives containing pharmacophore 1,3-oxazole moiety have been obtained. Composition and structure of the synthesized compounds have been confirmed by mass spectrometry and NMR spectroscopy data.

Alkylation of 4-(phenylthio)-1H-pyrazol-5-ols with methyl bromoacetate has afforded a series of phenyl pyrazolyl sulfides which have been oxidized into sulfones. The resulting esters have been hydrolyzed into the corresponding acids. The synthesized compounds potentially exhibit biological activity.

In the title phosphorylated compound, C20H26Cl3N2O6P, the phthalimide unit is essentially planar (r.m.s. deviation = 0.0129 Å) and the O atoms of this unit deviate from the mean plane by 0.080 (3) and 0.041 (3) Å. In the crystal, pairs of molecules are linked by N—H...O and weak C—H...O hydrogen bonds involving the same acceptor atom, forming inversion dimers. In addition, π–π stacking interactions between the phthalimide groups, with a centroid–centroid distance of 3.7736 (13) Å, and further weak C—H...O hydrogen bonds connect the inversion dimers into columns along [0-11].

A series of novel 2-oxoimidazolidine derivatives were synthesized and their antiviral activities against BK human polyomavirus type 1 (BKPyV) were evaluated in vitro. Bioassays showed that the synthesized compounds 1-{[(4E)-5-(dichloromethylidene)-2-oxoimidazolidin-4-ylidene]sulfamoyl}piperidine-4-carboxylic acid (5) and N-Cyclobutyl-N'-[(4E)-5-(dichloromethylidene)-2-oxoimidazolidin-4-ylidene]sulfuric diamide (4) exhibited moderate activities against BKPyV (EC50 =5.4 and 5.5 μm, respectively) that are comparable to the standard drug Cidofovir. Compound 5 exhibited the same cytotoxicity in HFF cells and selectivity index (SI50 ) as Cidofovir. The selectivity index of compound 4 is three times less than that of Cidofovir due to the higher toxicity of this compound. Hence, these compounds may be taken as lead compound for further development of novel ant-BKPyV agents.

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the essential reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological conditions. A series of chromene-based sulfonamides were synthesized and tested as possible CA inhibitors. Their inhibitory activity was assessed against the cytosolic human isoforms hCA I, hCA II and the transmembrane hCA IX and XII. Several of the investigated derivatives showed interesting inhibition activity towards the tumor associate isoforms hCA IX and hCA XII. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds, within the active site of hCA IX.

The regression QSAR models were built to predict the antimicrobial activity of new thiazole derivatives. Compounds with high predicting activity were synthesized and evaluated against Gram-positive and Gram-negative bacteria and fungi. 1,3-Thiazole-4-ylphosphonium salts 4 and 5 displayed good antibacterial properties and high antifungal activity. The predictions are in a good agreement with the experiment results, which indicate the good predictive power of the created QSAR models.

Reactions of substituted 2-hydroxyalkyl-1,3-thiazole-5-carbaldehydes and 5-hydroxyalkyl-1,3-thiazole-2-carbaldehydes with phenylhydrazine, isoniazid, N-substituted rhodanines were performed as well as Biginelli reaction with acetoacetic ester and urea. As a result, new 1,3-thiazole derivatives were obtained. They are of interest as potential bioactive substances.

Reactions of derivatives of diethyl 1-acylamino-2,2,2-trichloroethylphosphonates with different pharmacophore aminoalkanols afforded new 5-hydroxyalkylamino-1,3-oxazole derivatives. The latter are promising substrates for producing new 4-phosphorylated peptidomimetics containing alcohol residues.

Multigram synthesis of (chlorosulfonyl)benzenesulfonyl fluorides is described. Selective modification of these building blocks at the sulfonyl chloride function under parallel synthesis conditions is achieved. It is shown that the reaction scope includes the use of (hetero)aromatic and electron-poor aliphatic amines (e.g., amino nitriles). Utility of the method is demonstrated by preparation of the sulfonyl fluoride library for potential use as covalent fragments, which is demonstrated by a combination of in silico and in vitro screening against trypsin as a model enzyme. As a result, several inhibitors were identified with activity on par with that of the known inhibitor.

A 1,2,4-triazole motif is present in numerous commercialized and investigational bioactive molecules. Despite its importance for medicinal chemistry, there is a lack of convenient combinatorial approaches toward this molecular core. Herein, we present a synthetic strategy suitable for the quick preparation of a library of structurally diverse 1,2,4-triazoles in a one-pot setting. The key steps include the formation of thioureas followed by S-alkylation using 1,3-propane sultone and consecutive ring closure leading to the desired 1,2,4-triazoles. Parallel synthesis yields thousands of 1,2,4-triazoles in a cost- and time-efficient manner from commercially available chemicals.

The study of effects caused by the conjugated bridge binding of heterocycles (forming of $\alpha,\omega$ -disubstituted polyenes) was performed by quantum-chemical and spectral methods. It is shown that such modification of chemical constitution is accompanied by essential changes in the donor-acceptor property and energy gap. For the quantitative estimation of the influence of substituents on the donor-acceptor characteristic, the topological index $\varphi_{0}$ is used. Also, the spectral effects of the substituents on the energy gap were studied; they were experimentally observed in the spectra of the heterocycles and their bridged derivatives.

Display Omitted A series of new predictive QSAR models is presented.Artificial Neural Networks used to build QSAR models.The models demonstrated good predictive ability.Cytotoxic activity of 3 compounds against Hep-2 cell line was the highest.Docking studies of 3 compounds predict their binding to the colchicine binding site of tubulin. Microtubules play a significant role in cell growth and functioning. Therefore inhibition of the microtubule assemblies has emerged as one of the most promising cancer treatment strategies. Predictive QSAR models were built on a series of selective inhibitors of the tubulin were performed by using Associative Neural Networks (ANN). To overcome the problem of data overfitting due to the descriptor selection, a 5-fold cross-validation with variable selection in each step of the analysis was used. All developed QSAR models showed excellent statistics on the training (total accuracy: 0.960.97) and test sets (total accuracy: 0.9597). The models were further validated by 11 synthesized 1,3-oxazole derivatives and all of them showed inhibitory effect on the Hep-2 cancer cell line. The most promising compound showed inhibitory activity IC50=60.2M. In order to hypothesize their mechanism of action the top three compounds were docked in the colchicine binding site of tubulin and showed reasonable docking scores as well as favorable interactions with the protein.