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Abstract: Triazoles and their fused derivatives are regarded as one of the most pharmacologically significant pillars due to their potent, broad, and numerous activities. This current review presents recent progress in the synthetic utility of 3-substituted-4-amino-5-mercapto[1,2,4]- triazoles as building blocks for a diverse range of fused [1,2,4]triazoles with pharmacological interest eg. pyrazolo-triazoles, triazolo-thiadiazoles, triazolo-triazoles, triazolo-thiadiazines, triazolo-triazines, triazolo-tetrazines, triazolo-thiadiazepines, and others. The biological activity of some triazoles and their fused derivatives are also presented. This suggests that triazoles can be particularly promising synthons in synthesis of functionalized heterocyclic compounds used in the design of novel, highly effective pharmaceuticals with a broad spectrum of bioresponses. All of these topics are drawn in this review from the period from 2000 to 2020.

A novel catalytic approach for the synthesis of symmetric and asymmetric azines has been developed. The environmentally benign protocol was achieved via condensation of 1-[(2-thienyl)ethylidene]hydrazine (1) with different aromatic aldehydes 2a–h and acetyl heterocyclic compounds (4, 6, 8, 10, and 12) in the presence of cellulose sulfuric acid (CSA) as the green catalyst. These procedures offer an interesting method for the large-scale industrial manufacture of azines due to their high percentage yield, mild reaction conditions, broad substrate range, and utilization of an economical and environmentally acceptable catalyst. Additionally, the molecular docking of the products to the monoamine oxidase (MAO-A) target protein was achieved to highlight the possible binding interaction with the amino acid residues Arg51, Glu43, Gly22, Gly49, Gly443, Ala272, Ile335, and Tyr407 at the point of binding. The binding interaction energy was discovered to be (− 6.48 kcal/mol) for the protein MAO-A (PDB ID: 2Z5X). The most effective azine derivatives 7 and 13 revealed some major conserved interactions between the MAO-A protein’s binding site amino acid residues and the PDB co-crystal ligand 2Z5X. Moreover, azine derivatives 3a and 3f showed the lowest binding activity with the target MAO-A.

Recently, Strontium oxide (SrO) nanoparticles (NPs) and hybrids outperformed older commercial catalysts in terms of catalytic performance. Herein, we present a microwave-assisted easy in situ solution casting approach for the manufacture of strontium oxide nanoparticles doped within a naturally occurring polymer, chitosan (CS), at varying weight percentages (2.5, 5, 10, 15, and 20 wt.% SrO/chitosan). To construct the new hybrid material as a thin film, the produced nanocomposite solutions were cast in petri dishes. The aim of the research was to synthesize these hybrid nanocomposites, characterize them, and evaluate their catalytic potential in a variety of organic processes. The strontium oxide-chitosan nanocomposites were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. All the results confirmed the formation of chitosan–strontium oxide nanocomposite. FTIR spectrum of nanocomposite showed the presence of a characteristic peak of Sr-O bond. Furthermore, XRD revealed that SrO treatment increased the crystallinity of chitosan. The particle size was calculated using the Debye–Scherrer formula, and it was determined to be around 36 nm. The CS-SrO nanocomposite has been proven to be a highly efficient base promoter for the synthesis of 2-hydrazono [1,3,4]thiadiazole derivatives. To optimize the catalytic method, the reaction factors were investigated. The approach has various advantages, including higher reaction yields, shorter reaction durations, and milder reaction conditions, as well as the catalyst’s reusability for several applications.

In this study, Chitosan-MgO nanocomposite was prepared using a simple chemical precipitation method and characterized using scanning electron microscopy (SEM). Chitosan-MgO nanocomposite samples we...

4-Amino-5-mercapto[1,2,4]triazole and its 3-substituted derivatives have proven to be of biological interest and provide access to a new class of biologically active heterocyclic compounds for biomedical applications. This study will be helpful for scientific researchers interested in the chemistry of bifunctional versatile compounds as it provides a collection of all the methods for the preparation of 3-substituted-4-amino-5-mercapto[1,2,4]triazoles with aliphatic, aromatic, and heterocyclic moieties during the period from 2000 to mid-2020.

In recent years, nanotechnology has become a considerable research interest in the area of preparation of nanocatalysts based on naturally occurring polysaccharides. Chitosan (CS), as a naturally occurring biodegradable and biocompatible polysaccharide, is successfully utilized as an ideal template for the immobilization of metal oxide nanoparticles. In this study, zinc oxide nanoparticles have been doped within a chitosan matrix at dissimilar weight percentages (5, 10, 15, 20, and 25 wt.% CS/ZnO) and have been fabricated by using a simple solution casting method. The prepared solutions of the nanocomposites were cast in a Petri-dish and were subsequently shaped as a thin film. After that, the structural features of the nanocomposite film have been studied by measuring the FTIR, SEM, and XRD analytical tools. FTIR spectra showed the presence of some changes in the major characteristic peaks of chitosan due to interaction with ZnO nanoparticles. In addition, SEM graphs exhibited dramatic morphology changes on the chitosan surface, which is attributed to the surface adsorption of ZnO molecules. Based on the results of the investigated organic catalytic reactions, the prepared CS/ZnO nanocomposite film (20 wt.%) could be a viable an effective, recyclable, and heterogeneous base catalyst in the synthesis of thiazoles. The results showed that the nanocomposite film is chemically stable and can be collected and reused in the investigated catalytic reactions more than three times without loss of its catalytic activity.

A novel series of 1-aryl-N-[4-phenyl-5-(arylazo)thiazol-2-yl)methanimines has been synthesized via the condensation of 2-amino-4-phenyl-5-arylazothiazole with various aromatic aldehydes. The synthesized imines were characterized by spectroscopic techniques, namely 1H and 13C-NMR, FTIR, MS, and Elemental Analysis. A molecular comparative docking study for 3a–f was calculated, with reference to two approved drugs, Molnupiravir and Remdesivir, using 7BQY (Mpro; PDB code 7BQY; resolution: 1.7 A°) under identical conditions. The binding scores against 7BQY were in the range of −7.7 to −8.7 kcal/mol for 3a–f. The high scores of the compounds indicated an enhanced binding affinity of the molecules to the receptor. This is due to the hydrophobic interactions and multi-hydrogen bonds between 3a–f ligands and the receptor’s active amino acid residues. The main aim of using in silco molecular docking was to rank 3a–f with respect to the approved drugs, Molnupiravir and Remdesivir, using free energy methods as greener pastures. A further interesting comparison presented the laydown of the ligands before and after molecular docking. These results and other supporting statistical analyses suggested that ligands 3a–f deserve further investigation in the context of potential therapeutic agents for COVID-19. Free-cost, PASS, SwissADME, and Way2drug were used in this research paper to determine the possible biological activities and cytotoxicity of 3a–f.

Copper oxide-chitosan nanocomposite was synthesized simply via simple solution casting method and was characterized by different analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Thermogravimetric analysis (TGA). The copper oxide content in the prepared nanocomposite film was estimated from the Energy-dispersive X-ray spectroscopy (EDS) and the copper content in the sample was found to be 12.57 wt%. From the XRD pattern, the average particle size was calculated using Debye-Scherrer formula and was found to be 33.5 nm. The TGA curves showed that the thermal stability of the hybrid nanocomposite was found to be superior to the native CS, which is attributed to the existence of the thermally stable CuO. The chitosan/CuO nanocomposite has proven to be an excellent heterogeneous base catalyst for regioselective 1,3-dipolar cycloaddition of hydrazonoyl chlorides 1a-j with enamine 2 to give 1,3,4-trisubstituted pyrazoles 3a-j in excellent yields. The performance of the nanocomposite was optimized by varying several reaction conditions.

Novel derivatives of benzochromene 9a–e and chromene 10a–e were synthesized via multi components reaction that utilizes azo dyes, malononitrile, and arylaldehydes as starting materials. The structures of the newly synthesized compounds were elucidated by the IR, 1H-NMR, 13C-NMR and mass spectral data. The new synthesized compounds were explored for their in-silico ADMET properties. The docking investigations verified good docking outcomes in terms of score and binding affinities of the examined compounds on the desired proteins, namely the GlcN-6-P synthase and PI3Ks. The in-vitro studies, which encompassed the antibacterial activity against two types of Gm +ve and two of Gm –ve, and the antifungal activity against four fungi micro-organisms were evaluated by the well diffusion method for the synthesized compounds. Moreover, the anticancer activity was tested against three human carcinoma cell lines [human colon carcinoma (HCT-116), human breast adenocarcinoma (MCF-7), and liver carcinoma (HEPG-2)], exhibiting promising anticancer activity in comparison to Vinblastine, Colchicine and Doxorubicin as standard drugs. The data suggests that some of the new derivatives of chromene scaffold which emerged promising in the in-silico molecular docking studies displayed good in-vitro antimicrobial and anticancer activities and could be exploited as leads for further optimization.

Chitosan copper (II) oxide nanocomposite was synthesized, characterized and used to synthesize [1,2,3]triazoles. Nanocomposite was characterized by using FTIR, XRD, FESEM, and EDS techniques, which reflected rough morphology. The powerful catalytic activity of hybrid nanocomposite was utilized to synthesize chalcones (3a-p) in relatively high yields (82%-98%) and multicomponent regio-selective cycloaddition of chalones, aryl halides (4), and sodium azide to afford the expected N-2-aryl[1,2,3]triazoles (5a-h) (80%-95% yield) rather than N-1-aryl[1,2,3]-triazoles (6a-h). The performance of nanomaterial was optimized by several variables. The capability of the nanocomposite was compared with previous work and the nanocomposite was found more efficient, economic and reproducible. The hybrid nanocomposite could be easily isolated form the reaction mixture and recycled four times without any significant loss of its catalytic activity. The reported catalyst is an inexpensive for good yields of the triazoles and may be used at industrial production for the reported compounds.

Recently, the development of nanocatalysts based on naturally occurring polysaccharides has received a lot of attention. Chitosan (CS), as a biodegradable and biocompatible polysaccharide, is considered to be an excellent template for the design of a hybrid biopolymer-based metal oxide nanocomposite. In this case, lanthanum oxide nanoparticles doped with chitosan at different weight percentages (5, 10, 15, and 20 wt% CS/La2O3) were prepared via a simple solution casting method. The prepared CS/La2O3 nanocomposite solutions were cast in a Petri dish in order to produce the developed catalyst, which was shaped as a thin film. The structural features of the hybrid nanocomposite film were studied by FTIR, SEM, and XRD analytical tools. FTIR spectra confirmed the presence of the major characteristic peaks of chitosan, which were modified by interaction with La2O3 nanoparticles. Additionally, SEM graphs showed dramatic morphological changes on the surface of chitosan, which is attributed to surface adsorption with La2O3 molecules. The prepared CS/La2O3 nanocomposite film (15% by weight) was investigated as an effective, recyclable, and heterogeneous base catalyst in the synthesis of pyridines and pyrazoles. The nanocomposite used was sufficiently stable and was collected and reused more than three times without loss of catalytic activity.

Objective and background Hydrazonoyl halides were used as precursors for the synthesis of a new series of bis-spiropyrazoles via reaction with 3,5-diarylidene-piperidone derivatives under ultrasound irradiation. The products were secluded in good yield after short reaction periods. Conclusion The anticancer activity of bis-spiropyrazoles against HepG2 (hepatic cancer), A549 (lung cancer) and CaCo2 (colon cancer) cell lines was screened. Three tested compounds 4b, 4c and 4f showed promising activity.

The use of energy efficient building systems can play a key role in reducing energy consumption and the adverse impacts of greenhouse gas (GHG) emission. The occupancy profile of residential dwellings has a notable influence on the effectiveness of selecting appropriate energy upgrade retrofits. Building simulation models can be integrated to determine the impact of independent occupancy profile in realizing a building’s carbon mitigation target. In this paper, the most desirable energy upgrade retrofits are suggested for three different occupancy profiles by considering important economic parameters, such as the initial investment, payback period and environmental parameter such as GHG emissions. The three occupancy profiles considered were a single adult, couple without children and couple with children. For this purpose, a calibrated energy model was developed for a single-detached family household in British Columbia, Canada, which was equipped with power sensors for monitoring the real time energy data. From the calibrated energy model, three different energy upgrade retrofits (solar, window, and wall/roof insulation) were modelled for the occupancy profiles chosen and the most suitable energy upgrades were suggested. The results show that solar panels contributed the most in energy cost reduction and upgraded windows had the least GHG emission. With suitable financial initiative, the combination of all the three energy upgrades can be the best option in terms of environment and economy.

The crystal structure of the title compound, which contains azomethine groups, is reported; its keto and enol tautomeric forms are investigated., The title compound, [(1-{4-[2-(2,4-di­hydroxy­phen­yl)diazen-1-yl]phen­yl}ethyl­idene)amino]­thio­urea, 1,1,2,2-tetra­chloro­ethane monosolvate, C15H15N5O2S·C2H2Cl4, was prepared from 4-(4-acetyl­phenyl­diazendi­yl)resorcinol and thio­semicarbazide and recrystallized from mixed solvents of tetra­chloro­ethane and n-hexane. 1H NMR and X-ray diffraction data are in support of the thione tautomeric form. The X-ray analysis shows the mol­ecule crystallizes as a zwitterion, with proton transfer from the nominal phenol to the azide group; the N—N bond length is 1.291 (5) Å, and an intra­molecular N—H⋯O hydrogen bond is formed. In the crystal, N—H⋯O, N—H⋯N and O—H⋯S hydrogen bonds connect the mol­ecules into a three-dimensional network. The tetra­chloro­ethane solvent mol­ecules are linked to this network through weak C—H⋯O linkages.

In this study, we tested two novel series of 5-arylazo-2-hydrazonothiazoles 6a–g and 2-hydrazono[1,3,4]thiadiazoles 12a–c as antimicrobial and anticancer agents. These series were prepared from the reactions of 2-{1-[4-(2,4-dihydroxyphenylazo)phenyl]ethylidene}thiosemi-carbazide (3) with α-keto hydrazonoyl halides and N-aryl arenecarbohydrazonoyl halides. The structures of the newly synthesized compounds were elucidated by infrared, 1H and 13C nuclear magnetic resonance, and gas chromatography mass spectrometry spectral data. The antibacterial activity against two types of Gm +ve bacteria and, two types for Gm –ve bacteria, and the antifungal activity against four fungi microorganisms were evaluated by a well diffusion method for the synthesized compounds. Of these novel compounds, thiazole derivatives 6a–g showed mostly promising antibacterial activity against Gm +ve strains and antifungal activity compared to the reference drugs. A successful step was achieved to explain of their mode of action through molecular docking of the most active molecules at a target enzyme, CYP51. Moreover, the antiproliferative activity was tested against three human carcinoma cell lines [human colon carcinoma (HCT-116), human breast adenocarcinoma (MCF-7), and human liver carcinoma (HEPG-2)], showing promising anticancer activities compared to the doxorubicin drug. The data suggest that the arylthiazole scaffold derivatives 6a–g exhibited good antimicrobial and anticancer activities and might be used as leads for further optimization.

Though the adult central nervous system has been considered a comparatively static tissue with little turnover, it is well established today that new neural cells are generated throughout the life. Neural stem/progenitor cells (NS/PCs) can self-renew and generate all types of neural cells. The proliferation of NS/PCs, and differentiation and fate determination of PCs are regulated by extrinsic factors such as growth factors, neurotrophins, and morphogens. Although several extrinsic factors that influence neurogenesis have already been reported, little is known about the role of soluble molecules in neural niche regulation. In this review, we will introduce the soluble molecule Akhirin and discuss its role in the eye and spinal cord during development.

A novel series of some hydrazones bearing thiazole moiety were generated via solvent-drop grinding of thiazole carbohydrazide 2 with various carbonyl compounds. Also, dehydrative-cyclocondensation of 2 with active methylene compounds or anhydrides gave the respective pyarzole or pyrazine derivatives. The structures of the newly synthesized compounds were established based on spectroscopic evidences and their alternative syntheses. Additionally, the anti-viral activity of all the products was tested against SARS-CoV-2 main protease (Mpro) using molecular docking combined with molecular dynamics simulation (MDS). The average binding affinities of the compounds 3a, 3b, and 3c (–8.1 ± 0.33 kcal/mol, –8.0 ± 0.35 kcal/mol, and –8.2 ± 0.21 kcal/mol, respectively) are better than that of the positive control Nelfinavir (–6.9 ± 0.51 kcal/mol). This shows the possibility of these three compounds to effectively bind to SARS-CoV-2 Mpro and hence, contradict the virus lifecycle.

2-(1-{4-[(4-Methylphenyl)sulfonamido]phenyl}ethylidene)thiosemicarbazide (3) was exploited as a starting material for the synthesis of two novel series of 5-arylazo-2-hydrazonothiazoles 6a - 6j and 2-hydrazono[1,3,4]thiadiazoles 10a - 10d, incorporating sulfonamide group, through its reactions with appropriate hydrazonoyl halides. The structures of the newly synthesized products were confirmed by spectral and elemental analyses. Also, the antimicrobial, anticancer, and DHFR inhibition potency for two series of thiazoles and [1,3,4]thiadiazoles were evaluated and explained by molecular docking studies and SAR analysis.

Drugs of cancer based upon ionizing radiation or chemotherapeutic treatment may affect breaking of DNA double strand in cell. DNA-PK enzyme has emerged as an attractive target for drug discovery efforts toward DNA repair pathways. Hence, the search for potent and selective DNA-PK inhibitors has particularly considered state-of-the art and several series of inhibitors have been designed. In this article, a novel benchmark DNA-PK database of 43 compounds was built and described. Ligand-based approaches including pharmacophore and QSAR modeling were applied and novel models were introduced and analyzed for predicting activity test for DNA-PK drug candidates. Based upon the modeling results, we gave a report of synthesis of fifteen novel 2-((8-methyl-2-morpholino-4-oxo-4 H -benzo[ e ][1,3]oxazin-7-yl)oxy)acetamide derivatives and in vitro evaluation for DNA-PK inhibitory and antiproliferative activities. These fifteen compounds overall are satisfied with Lipinski's rule of five. The biological testing of target compounds showed five promising active compounds 7c , 7d , 7f , 9e and 9f with micromolar DNA-PK activity range from 0.25 to 5 µM. In addition, SAR of the compounds activity was investigated and confirmed that the terminal aryl moiety was found to be quite crucial for DNA-PK activity. Moreover flexible docking simulation was done for the potent compounds into the putative binding site of the 3D homology model of DNA-PK enzyme and the probable interaction model between DNA-PK and the ligands was investigated and interpreted.

A simple one-pot method is reported for the synthesis of several novel series of chromeno[4′,3′:4,5]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine-6,14-diones, chromeno[4′,3′:4,5]pyr­ido[2,3-d]thiazolo[3,2-a]pyrimidine-6,14-diones, and chrom-­eno[4′′,3′′:4′,5′]pyrido[2′,3′:4,5]pyrimido[2,1-b][1,3]thiazine-6,15-dione by a multicomponent reaction of salicylaldehyde, ethyl acetoacetate, and the appropriate fused heterocyclic amines in refluxing glacial acetic acid. The structures of the newly synthesized compounds were established by spectroscopy and elemental analyses. The mechanism of the single-step reaction was elucidated.

A facile and convenient synthesis of [1,2,3]triazole, [1,2,4]triazolo[5,1-c][1,2,4]triazine, and pyrazolo[5,1-c][1,2,4]triazine derivatives incorporating an antipyrin-4-yl or antipyrin-4-ylcarboxamide moiety via the versatile, readily accessible 2-cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide is described. Structures of the synthesized compounds were elucidated by means of IR, 1H NMR, 13C NMR, and mass spectral data. The biological activity of the newly synthesized compounds was examined and some of them were found to possess anticancer and antimicrobial activities.

Novel hydrazonoyl halides 3, 5 and bis-hydrazonoyl halides 7, 9 were synthesized. The synthetic utility of bis-hydrazonoyl halide 7 was explored to prepare novel bis-azole 13 with antipyrine moiety. On the other hand, [1,3,4]thiadiazol-2(3H)-ylidene 17 and thiazol-2(3H)-ylidene 21 derivatives, with antipyrine moiety, were prepared from the reaction of 3-mercapto-3-(phenylamino)acrylamide derivative 10 with N-phenyl benzenecarbohydrazonoyl chloride (14) and 3-(2-bromoacetyl)-2H-chromen-2-one (18), respectively. The structures of the isolated products were confirmed by spectral data (IR, (1)H-NMR, (13)C-NMR, MS) and elemental analyses. The anti-cancer activitiy of the synthesized products against the colon carcinoma (HCT) cell line was determined and the results revealed promising activity of compound 3. In addition, the antimicrobial activity of some selected products was evaluated. The results proclaimed that compounds 9, 17, and 21 have high antibacterial activity against Gram-positive bacteria (SA, BS) and Gram-negative bacteria (PA, EC).

This review provides a survey on the synthesis and reactions of ethylidenethiosemicarbazides during the period from 2004 to 2015. These reactions proved useful for synthesis of various aspects of heterocyclic chemistry.

1,3-Dipolarcycloaddition reactions of 6-arylmethylene-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ones (1) with nitrilimines 3 were investigated in benzene and chloroform. The reaction products were 2′,4′,6,7,8,9-hexahydro-2′,4′,5′-triaryl spiro[benzocycloheptene-6(5H),3′(3H-pyrazol)-5-ones (4) or 2′,3′,6,7,8,9-hexahydro-2′,3′,5′-triaryl spiro[benzocycloheptene-6(5H),4′(4H-pyrazol)-5-ones (5). X-ray crystallographic analysis was carried out for compound 5b. It was found that the regioselectivity of the produced compounds was altered based on changing solvent type.

Microwave-assisted synthesis of some novel compounds, namely, 3-(2-methyl-1H-indol-3-yl)-6-aryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 5a,b was accomplished via bromination of 2-methyl-3-[4-(arylideneamino)-5-mercapto-4H-[1,2,4]triazol-3-yl]-1H-indoles 3a,b. Also, new [1,3,4]thiadiazoles 12a,b, [1,2,4]triazoles 15a,b and [1,3,4]oxadiazoles 19a,b, with indole moieties, were prepared by cyclization of 1-[(2-methyl-1H-indole)-3-carbonyl]thiosemicarbazides 8a,b under microwave irradiation using different reaction conditions. Moreover, reaction of acid hydrazide 7 with ethyl 2-(N-phenylhydrazono)-3-oxobutanoate (20) gave the respective phenylhydrazonopyrazole derivative 21 under the reaction conditions employed. The structures of the synthesized compounds were assigned based on elemental analyses and spectral data (IR, (1)H-NMR, (13)C-NMR, MS). The antifungal and antibacterial activities of the new products were also evaluated.

Novel N-arylpyrazole-containing enaminones 2a,b were synthesized as key intermediates. Reactions of 2a,b with active methylene compounds in acetic acid in the presence of ammonium acetate afforded substituted pyridine derivatives 5a-d. Enaminones 2a,b also reacted with aliphatic amines such as hydrazine hydrate and hydroxylamine hydrochloride to give bipyrazoles 8a,b and pyrazolylisoxazoles 9a,b, respectively. On the other hand, treatment of 2a,b with a heterocyclic amine and its diazonium salt yielded the respective [1,2,4]triazolo[4,3-a]pyrimidines 12a,b and pyrazolylcarbonyl[1,2,4]triazolo-[3,4-c][1,2,4]triazines 14a,b. Moreover, 2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (17) was prepared via reaction of enaminone 2a with aminothiouracil (15). Cyclocondensation of 17 with the appropriate hydrazonoyl chlorides 18a-c gave the corresponding pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones 21a-c. The cytotoxic effects of compounds 2b, 14a and 17 against human breast cell line (MCF-7) and liver carcinoma cell line (HEPG2) were screened and in both lines they showed inhibition effects comparable to those of 5-fluorouracil, used as a standard. The antimicrobial activity of some products chosen as representative examples was also evaluated.

A chitosan-MgO hybrid nanocomposite was prepared using a simple chemical precipitation method and characterized using Fourier transform spectroscopy (FTIR), elemental analysis (EDX), and scanning electron microscopy (SEM). The nanocomposite was served as a powerful ecofriendly basic catalyst under microwave irradiation in the synthesis of two novel series of 5-arylazo-2-hydrazonothiazoles 4a&ndash, j and 2-hydrazono[1,3,4]thiadiazoles 8a&ndash, d, incorporating a sulfonamide group. The structures of the synthesized products were elucidated by spectral data and elemental analyses. Also, their yield percentages were calculated using triethylamine (as a traditional catalyst) and chitosan-MgO nanocomposite (as a green recyclable catalyst) in a comparative study.

Derivatives of novel penta-heterocyclic ring systems, namely, 5,6,7,11-tetrahydro-15Hbenzo[6',7']cyclohepta[1',2':4,5]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-15-ones (9a-g) and 6,7-dihydrobenzo[6',7']cyclohepta[1',2':4,5]pyrido[2,3-d][1,3]thiazolo[3,2-a]pyrimidin-15(5H)ones (11a-d) were easily prepared via reactions of 3-thioxo-2,3,4,7,8,9-hexahydro-1Hbenzo[6',7']cyclohepta[1',2':4,5]pyrido[2,3-d]pyrimidin-1-one (3) with hydrazonoyl halides and active methylene compounds, respectively. The foregoing reactions were carried out with conventional heating as well as pressurized microwave irradiation and a comparative study was employed.

Heteroaromatization of ethyl 2-cyano-4-oxo-2-(2-oxo-2-arylethyl)-4-arylbutanoates 3a,b with ammonium acetate gave ethyl 2,6-diarylisonicotinates 4a,b. Treatment of the latter with acetonitrile afforded novel beta-oxoalkanonitriles 6a,b. Reactions of 6a,b with phenyl hydrazine and hydroxylamine gave the corresponding pyridyl aminopyrazoles 8a,b and pyridyl aminoisoxazoles 10a,b, respectively.