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Background: The monoamine oxidase (MAO) enzymes are important drug targets. The inhibitors of MAO-A and MAO-B have been used to treat the symptoms of depression and Parkinson’s disease. background: The monoamine oxidase (MAO) enzymes are important drug targets and inhibitors of MAO-A and MAO-B have been used to treat the symptoms of depression and Parkinson’s disease. Methods: A series of seventeen pyridazinone-substituted benzenesulfonamides was synthesized and evaluated as potential inhibitors of human MAO-A and MAO-B. This study is a continuation of our interest in the pharmacological activities of sulfonamide compounds. Results: Among the compounds evaluated, only 10 and 18 demonstrated appreciable inhibition of MAO-B with IC50 values of 2.90 and 4.36 µM, respectively. None of the benzenesulfonamides inhibited the MAO-A isoform. Potential binding orientations and interactions of 10 and 18 with the active site of MAO-B were investigated by computational approaches. method: A series of seventeen pyridazinone-substituted benzenesulfonamides was synthesized and evaluated as potential inhibitors of human MAO-A and MAO-B. This study is a continuation of our interest in the pharmacological activities of sulfonamide compounds. Conclusion: Although these potencies are modest, this study is the first report on MAO inhibition by this class of compounds. Active MAO-B inhibitors may serve as leads for the future discovery of therapeutic agents for neurodegenerative disorders, such as Parkinson’s disease. conclusion: Although these potencies are modest, this study is the first report of MAO inhibition by this class of compounds. Active MAO-B inhibitors may serve as leads for the future discovery of therapeutic agents for neurodegenerative disorders such as Parkinson’s disease.

A new route to 5-amino-1,2,4-thiadiazole derivatives via reaction of N-chloroamidines with isothiocyanates has been proposed. The advantages of this method are high product yields (up to 93%), the column chromatography-free workup procedure, scalability and the absence of additive oxidizing agents or transition metal catalysts. The 28 examples of 5-amino-1,2,4-thiadiazole derivatives obtaining via the proposing protocol were evaluated in vitro against ESKAPE pathogens strains (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter cloacae). It was found that compounds 5ba, 5bd, 6a, 6d and 6c have potent antibacterial activity (MIC values 0.09-1.5 μg mL

A regioselective method for the synthesis of substituted (4R*,5S*,6R*)-2-thioxohexahydro-pyrimidine-5-carbohydrazides from the corresponding diastereomers of hexahydro-2H-chromeno[4,3-d]pyrimidines was developed. In acidic medium, the obtained hydrazides are prone to retro reaction to give hexahydro-2H-chromeno[4,3-d]pyrimidines.

The direct N-arylation of cyclic amides can be considered a pivotal issue for modern organic chemistry. Here, we report the method for copper-catalyzed N-arylation of diverse oxadiazolones by diaryliodonium salts in mild conditions in high yields (up to 92%) using available CuI as a catalyst. The developed method allows to efficiently utilize both symmetric and unsymmetric diaryliodonium salts bearing auxiliary groups such as 2,4,6-trimethoxyphenyl (TMP). The evaluation of steric effects in aryl moieties to the chemoselectivity of N- and O-arylation of the 1,2,4-oxadiazol-5(4H)-ones exhibited the high potential of mesityl-substituted diaryliodonium salts as a selective arylation reagent. The structural study suggests that steric accessibility of N-atom in 1,2,4-oxadiazol-5(4H)-ones impact to arylation with sterically hindered diaryliodonium salts. The synthetic application of proposed method was also demonstrated on selective arylation of 1,3,4-oxadiazol-2(3H)-ones and 1,2,4-oxadiazole-5-thiol.

Abstract A two-stage method for the preparation of 2-(3-carboxymethylindazol-1-yl)anilines using the N-arylation reaction of 3-carboxymethylindazoles with o-nitrohaloarenes and subsequent reduction of nitro-containing intermediates with tin(II) chloride was developed. The experimental results showed that the use of the synthesized compounds as fluorophores in the visible region of the spectrum is promising.

An efficient one-pot method was developed for the synthesis of 2-(1,2,4-oxadiazol-5-yl)anilines via the reaction of amidoximes with isatoic anhydrides in a NaOH–DMSO medium at ambient temperature. The method allows to obtain structurally diverse substituted anilines bearing the 1,2,4-oxadiazole motif in moderate to excellent yields without the utilization of protective groups. The reaction scope includes aryl, hetaryl, and cycloalkyl amidoxime and isatoic anhydrides with different substituents in the aromatic ring as well as at the amide N atom. Structures of two anilines were studied by single crystal X-ray diffraction method and intramolecular hydrogen bonding between N atom of oxadiazole moiety and NH2 group was revealed.

A series of 2,5-dibromo-3-R-thiophenes (R = COONa 1, CN 2, CONH2 3, CON(H)Me 4, CON(H)Bn 5, CON(CH2CH2)2O 6, CON(H)NH2 7, CON(H)OH 8) were prepared and studied via high-resolution ESI-MS, 1H and 13...

New pyrazolo[1,5-a]quinoxalin-4-ones were obtained by reductive cyclization from the corresponding 1-(2-nitroaryl)pyrazole-5-carboxylates. Alternatively, pyrazolo[1,5-a]quinoxalines were prepared from N-hydroxypyrazolo[1,5-a]quinoxalines.

Efficient approaches towards the synthesis of various N-substituted 1,3,5-triazinanes based on a transformation of N-alkyl-1,5,3-dioxazepanes or on a domino reaction involving condensation of various amines, amides, and paraformaldehyde are described for the first time. Mg(ClO4)2 was shown to be one of the most potent additives for the condensation. The proposed approaches permit the synthesis of a broad spectrum of substituted sym-triazinanes in good yields with relatively easy workup. In the case of the multicomponent reaction, the approach allows the preparation of the target substances from simple and easily accessible reagents. The representatives of the resulting compounds were found to possess no antimicrobial or cytotoxic activity in in vitro bioassays.

A 1:1 reaction of 8-(dihydroimidazolyl)quinoline (abbreviated as L) with MCl2·2H2O (M = CoII, NiII, CuII, ZnII) conducted in EtOAc (for ZnII and CuII) or MeOH (NiII and CoII) at 50 °C for 10 min provided the respective air- and shelf-stable [MCl2L] complexes (94–96%). The catalytic activity of these well-defined species was evaluated in L-lactide ring-opening polymerization (ROP) that was conducted in the presence of 2-hydroxyethylmethacrylate (HEMA) as a nucleophilic initiator. The biocompatible zinc(II) complex was found to be more catalytically active in ROP compared to the other three complexes as well as SnOct2, a common reference catalyst. The zinc(II)-catalyzed ROP also gives the macromolecular product with the lowest polydispersity index (1.2). The applicability of the HEMA-terminated PLA, prepared in the presence of the [ZnCl2L] complex, was demonstrated when PLA was converted into amphiphilic copolymer PLA-PEG via the thiol-ene click reaction. The PLA-PEG copolymer was shown to form nanospheres (calculated mean diameter 95 ± 10 nm) characterized by low particle size distribution. This – along with anticipated lower toxicity of [ZnCl2L] traces in the polymer – makes these nanospheres potentially applicable as vehicles for intravenous drug delivery.

The direct N-arylation of cyclic amides can be considered a pivotal issue for modern organic chemistry. Here, we report the method for copper-catalyzed N-arylation of diverse oxadiazolones by diaryliodonium salts in mild conditions in high yields (up to 92%) using available CuI as a catalyst. The developed method allows to efficiently utilize both symmetric and unsymmetric diaryliodonium salts bearing auxiliary groups such as 2,4,6-trimethoxyphenyl (TMP). The evaluation of steric effects in aryl moieties to the chemoselectivity of N- and O-arylation of the 1,2,4-oxadiazol-5(4H)-ones exhibited the high potential of mesityl-substituted diaryliodonium salts as a selective arylation reagent. The structural study suggests that steric accessibility of N-atom in 1,2,4-oxadiazol-5(4H)-ones impact to arylation with sterically hindered diaryliodonium salts. The synthetic application of proposed method was also demonstrated on selective arylation of 1,3,4-oxadiazol-2(3H)-ones and 1,2,4-oxadiazole-5-thiol.

A one-pot ambient-temperature procedure for the synthesis of 3,5-disubstituted-1,2,4-oxadiazoles from amidoximes and carboxylic acids under superbase-promoted conditions is reported.

A series of novel aromatic primary sulfonamides decorated with diversely substituted 1,2,4-oxadiazole periphery groups has been prepared using a parallel chemistry approach. The compounds displayed a potent inhibition of cytosolic hCA II and membrane-bound hCA IX isoforms. Due to a different cellular localization of the two target enzymes, the compounds can be viewed as selective inhibition tools for either isoform, depending on the cellular permeability profile. The SAR findings revealed in this study has been well rationalized by docking simulation of the key compounds against the crystal structures of the relevant hCA isoforms.

An efficient and mild one-pot protocol has been developed for the synthesis of 1,2,4-oxadiazoles via the reaction of amidoximes with dicarboxylic acid anhydrides in a NaOH/DMSO medium. The method allows the synthesis of diversely substituted carboxylic acids bearing the 1,2,4-oxadiazole motif, – a popular building block for pharmaceutical research, in moderate to excellent yields. The reaction scope includes aromatic and heteroaromatic amidoximes as well as five-, six- and seven-membered anhydrides. The advantages of this procedure are proven gram-scalability and the use of inexpensive starting materials, which from a process chemistry point of view are essential for future industrial applications.

An expanded set of pyridazine-containing benzene sulfonamides was investigated for inhibition of four human carbonic anhydrase isoforms, which revealed a pronounced inhibition trend toward hCA IX, a cancer-related, membrane-bound isoform of the enzyme. Comparison of antiproliferative effects of these compounds against cancer (PANC-1) and normal (ARPE-19) cells at 50 μM concentration narrowed the selection of compounds to the eight which displayed selective growth inhibition toward the cancer cells. More detailed investigation in concentration-dependent mode against normal (ARPE-19) and two cancer cell lines (PANC-1 and SK-MEL-2) identified two lead compounds one of which displayed a notable cytotoxicity toward pancreatic cancer cells while the other targeted the melanoma cells. These findings significantly expand the knowledge base concerning the hCA IX inhibitors whose inhibitory potency against a recombinant enzyme translates into selective anticancer activity under hypoxic conditions which are aimed to model the environment of a growing tumor.

Series of structurally diverse 2-imidazoline derivatives have been synthesized by condensation of substituted aldehydes with ethylenediamine, Pd-catalyzed N-arylation of 2-imidazolines and by the formation of 1,2,4-oxadiazoles and benzoxazepines from 2-imidazoline-containing precursors. The 2-imidazoline derivatives were evaluated as potential inhibitors of human monoamine oxidase (MAO) A and B. Among the 2-imidazolines, good potency inhibitors were discovered with compound 9p (IC50 = 0.012 µM) being the most potent MAO-B inhibitor, while compound 9d (IC50 = 0.751 µM) was the most potent MAO-A inhibitor of the series. These potencies are in the same range as those of reference MAO inhibitors used in the clinic. Among 33 compounds evaluated, 13 exhibited IC50 values in the submicromolar range for the inhibition of an MAO isoform. It is postulated that the imidazoline moieties of some of these inhibitors may be recognized by the imidazoline I2-binding site of MAO. Good potency MAO inhibitors may be useful for the treatment of neuropsychiatric and neurodegenerative disorders such as depression and Parkinson’s disease, and future application for the treatment of prostate cancer, congestive heart failure and Alzheimer’s disease. In addition, high potency 2-imidazoline-derived MAO inhibitors may be used as potential probes for the imidazoline binding sites of the MAOs, as well as to determine alternative binding regions of imidazoline within the MAO active site.

Structures of three tetrahalophthalic anhydrides (TXPA: halogen = Cl (TCPA), Br (TBPA), I (TIPA)) were studied by X-ray diffraction, and several types of halogen bonds (HaB) and lone pair···π-hole (lp···πh) contacts were revealed in their structures. HaBs involving the central oxygen atom of anhydride group (further X···O(anhydride) were recognized in the structures of TCPA and TBPA. In contrast, for the O(anhydride) atom of TIPA, only interactions with the π system (π-hole) of the anhydride ring (further lp(O)···πh) were observed. Computational studies by a number of theoretical methods (molecular electrostatic potentials, the quantum theory of atoms in molecules, the independent gradient model, natural bond orbital analyses, the electron density difference, and symmetry-adapted perturbation theory) demonstrated that the X···O(anhydride) contacts in TCPA and TBPA and lp(O)···πh in TIPA are caused by the packing effect. The supramolecular architecture of isostructural TCPA and TBPA was mainly affected by X···O(acyl) and X···X HaBs, and, for TIPA, the main contribution provided I···I HaBs.

N-Furfuryl allylamines, readily accessible from corresponding furfurals or furfuryl amines, react with a broad range of arylsulfonyl chlorides with the formation of a 3a,6-epoxyisoindole core in one synthetic stage. Usually, in boiling water, the interaction sequence involves two consecutive steps: the Hinsberg reaction and the intramolecular Diels–Alder furanе (IMDAF) reaction. The scope and limitations of the proposed method were thoroughly investigated, and it was revealed that the key [4 + 2] cycloaddition step proceeds through an exo-transition state, giving rise to the exclusive formation of a single diastereomer of the target heterocycle. The method allows the ability to obtain N-sulfaryl-substituted 3a,6-epoxyisoindoles and 4a,7-epoxyisoquinolines, which are potentially useful substrates for further transformations and subsequent bioscreening, in particular antimicrobial activity.

The monoamine oxidase (MAO) enzymes are key metabolic enzymes of neurotransmitter and other bioactive amines, and represent important drug targets for the treatment of neuropsychiatric and neurodegenerative disorders. Inhibitors of MAO are established medications for the treatment of depression and Parkinson’s disease, and may have future roles in other disease states such as the therapy of prostate cancer, cardiovascular disease and inflammatory diseases. Based on these considerations, the present study synthesizes a series of 22 pyrazolo[1,5-a]quinoxalin-4-one derivatives and evaluated them as potential inhibitors of human MAO-A and MAO-B. The results show that 8 derivatives inhibit MAO-A, and 3 derivatives inhibit MAO-B with IC50 values in the submicromolar range (

A simple and convenient one-pot method is reported for the synthesis of (E)-3-(3-aryl(heteroaryl, alkyl)-1,2,4-oxadiazole-5-yl)acrylic acids utilizing readily accessible or commercially available substituted benzamidoximes and inexpensive exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride. The method is based on the reaction of amidoximes with the anhydride in a basic medium at RT followed by an acid-catalyzed retro-Diels-Alder reaction. The observed stereoselective heterocyclization/retro-Diels-Alder cascade process is suitable for the synthesis of a wide range of substituted (E)-1,2,4-oxadiazole-5-ylacrylic acids featuring electron donating and electron withdrawing groups on the aryl moiety, as well as heteroaryl or alkyl substituents at position 3 of the 1,2,4-oxadiazole ring (42–79%; 15 examples).

An expanded set of diversely substituted 1,2,4-oxadiazole-containing primary aromatic sulfonamides was synthesized and tested for inhibition of human carbonic anhydrase I, II, IX and XII isoforms. The initial biochemical profiling revealed a significantly more potent inhibition of cancer-related, membrane-bound isoform hCA IX (reaching into submicromolar range), on top of potent inhibition of hCA XII that is another cancer target. The observed structure-activity relationships have been rationalized by molecular modeling. Comparative single-concentration profiling of the carbonic anhydrase inhibitors synthesized for antiproliferative effects against normal (ARPE-19) and cancer (PANC-1) cell lines under chemically induced hypoxia conditions revealed several candidate compounds selectively targeting cancer cells. More in-depth characterization of these leads revealed two structurally related compounds that showed promising selective cytotoxicity against pancreatic cancer (PANC-1) and melanoma (SK-MEL-2) cell lines.

A two-stage selective synthesis of new substituted 5-hydroxypyrazolo[1,5-a]quinoxalin-4-ones from ethyl 3-arylpyrazole-5-carboxylates and activated o-chloronitroarenes substrates has been developed.

The imidazolin-1-yl azine moiety, constructed using a recently developed Buchwald–Hartwig-type arylation methodology, displays excellent chemical stability under subsequent microwave-assisted Pd-catalyzed amination with a range of N-nucleophiles. This finding extends the usage of imidazolin-1-yl azines for bioactive compound library design. The latter is exemplified herein by the discovery of micromolar kinase inhibitors.

The present study investigates the monoamine oxidase (MAO) inhibition properties of a series of ten 5-aryl-1,3,4-oxadiazol-2-ylbenzenesulfonamides. The target compounds were synthesized by dehydration of the corresponding N,N′-diacylhydrazines with phosphorus oxychloride to yield the 1,3,4-oxadiazole cycle with concomitant transformation of the sulfonamide to the sulfonyl chloride group. Treatment with aqueous ammonia in acetonitrile regenerated the target sulfonamides. The results of the enzymology document that these compounds are potent and specific MAO-B inhibitors with the most potent compound exhibiting an IC50 value of 0.0027 µM. An analysis of the structure-activity relationships shows that the 4-benzenesulfonamides are significantly more potent MAO-B inhibitors than the corresponding 3-benzenesulfonamides, and that the corresponding N,N′-diacylhydrazine synthetic precursors are weak MAO inhibitors. Although MAO inhibition by oxadiazole compounds are known, this is the first report of nanomolar MAO inhibition potencies recorded for sulfonamide derivatives. MAO-B specific inhibitors such as those discovered here may be of interest in the treatment of neurodegenerative disorders such as Parkinson’s disease.

Replacement of amide moiety with the 1,2,4-oxadiazole core in the scaffold of recently reported efflux pump inhibitors afforded a novel series of oxadiazole/2-imidazoline hybrids. The latter compounds exhibited promising antibacterial activity on both Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas fluorescens) strains. Furthermore, selected compounds markedly inhibited the growth of certain drug-resistant bacteria. Additionally, the study revealed the antiproliferative activity of several antibacterial frontrunners against pancreas ductal adenocarcinoma (PANC-1) cell line, as well as their type-selective monoamine oxidase (MAO) inhibitory profile.

Herein, we reported a general, convenient, and efficient synthesis of 3,5-disubstituted-1,2,4-oxadiazoles via cyclodehydration of O -acylamidoximes in the superbase system MOH/DMSO (M = Li, Na, K). Excellent isolated yields (up to 98%) were attained within short reaction times (10–20 min). In addition, mild reaction conditions and a simple work-up procedure allow the synthesis of a wide range of heat-labile 1,2,4-oxadiazole-containing substances.