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Coumarins are the family of benzopyrones, in which benzene ring amalgamated with the pyrone ring. Their versatile oxygen-containing heterocyclic structure and physicochemical characteristics are responsible to attract great attention from medicinal chemists and pharmacologists and for being a privileged scaffold in medicinal chemistry. In this study, 1, 3, 4 -oxadiazole incorporated a series of new coumarin derivatives have been synthesized. Structures of the newly synthesized compounds were established on the basis of FT-IR, 1H NMR spectroscopic techniques and elemental analysis. The synthesized compounds were screened for their in vitro antifungal activity against five pathogenic fungal strains: Aspergillus niger, Penicillium notatum, Saccharomyces cerevisiae, Penicillium chrysogenum and Neurospora crassa by disk-diffusion method. All the compounds were found to have significant antifungal activity against all the fungal strains.

In the undertaken research, 5-(5-H/Br benzofuran-2-yl)-N'-((-2-(p-tolyloxy) substituted quinolin-3-yl)methylene)-1-phenyl-1H-pyrazole-3-carbohydrazide (3a-h)  on treatment with acetic anhydride afforded novel 1-(5-(5-(5-H/Br benzofuran-2-yl)-1-phenyl-1H-pyrazol-3-yl)-2-(-2-(p-tolyloxy)substitutedquinolin-3-yl)-1,3,4-oxadiazol-3(2H)-yl)ethanone derivatives (4a-h). 5-fused heteryl pyrazole-3-carbohydrazone (3a-h) needed  for the synthesis of  4a-h were synthesized by reaction of 2-(p-tolyloxy) substituted quinoline-3-carbaldehyde (2a-h) with 5-(5-H/Br benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazides (1a-b) in ethanol as solvent. The structures of the newly synthesized compounds were identified on the basis of elemental analysis and spectral studies like IR, 1H NMR and Mass spectra. The in-vitro antibacterial screening of these synthesized compounds against E. coli, S. aureus, E. areogenes and B. thurengienesis relative to the reference standard Chloramphenicol have been found to possesses good to moderate inhibitory activity.

The present communication deals with the synthesis of some N´-alkylidene/arylidene-2-(4-substituted-5-phenyl-1,3,4-oxadiazol-2-ylthio) aceto/arylhydrazides, their characterization and antimicrobial activity against medically important microbes. The final compounds were synthesized by reaction of 2-(4-substituted-5-phenyl-1,3,4-oxadiazol-2-ylthio) acetohydrazide with various aliphatic and aromatic aldehydes in presence of glacial acetic acid in ethanol. The structures of the synthesized compounds were established by IR, NMR and Mass spectral studies. The antimicrobial activity was studied against Staphylococcus aureus (MTCC 87), Bacillus subtilis (MTCC 121), Pseudomonas aeruginosa (MTCC 424), Escherichia coli (MTCC 40), Candida albicans (MTCC 183), Fusarium solani (MTCC 2935) using agar well diffusion method. Some of the tested compounds exhibited activity against all the microorganisms.  In particular, compounds 12, 19 and 22 were found to be active against all the tested bacterial strains and fungal strain Candida albicans. It was concluded that number and position of electron withdrawing substituents affects the activity.

Triazines are interesting class of heterocyclic compounds. Various synthetic analogs of symmetric triazines have been prepared and evaluated for many pharmacological activities in different models with desired findings. Some analogs have shown potent pharmacological activity and may be considered as lead molecule for the development of future drugs. This review is an attempt to organize the chemical aspects of 1,3,5 triazine analogs reported till date systematically

A simple and efficient methodology for the synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives has been developed by the condensation of aldehydes, ethyl acetoacetate  and urea using Germanium (IV) iodide as catalyst. All the reactions were carried out at acetonitrile reflux and completed within 2 to 5 hours of reaction with good yields. All the products were very clear and confirmed by spectroscopy analysis.

5-(substituted/unsubstituted benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazides 1a-b  on reaction with phenylisothiocyanate, potassium thiocyanate, carbon disulphide in pyridine and carbon disulphide in KOH followed by hydrazine hydrate afforded nitrogenous, sulphur bridgehead heterocycles 2-5a-d respectively. The structures of the newly synthesized compounds were elucidated by elemental analysis and spectral data such as IR, 1H NMR, 13C NMR and mass spectra. In addition the in vitro antibacterial and antifungal properties were tested for these synthesized compounds against B. subtilis, S. aureus, E. coli, P. aeruginosa and A. niger compared with ampicillin and clotrimazole as reference drugs. Synthesized compounds were found to possess moderate to excellent activity against selected strains.

5-(7-bromo-5-chloro-3-methylbenzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazide 1 underwent a series of hetero-cyclization reactions with different chemical reagents such as triethylorthoformate, acetic acid in phosphorous oxychloride, benzoic acid in phosphorous oxychloride,  N,N’carbonyldiimidazole in dioxane, carbon disulphide in pyridine to afford substituted 1,3,4-oxadiazoles 2, 3, 4, 5 and 6 respectively.  Extending the reaction of 6 with 4-(2-chloroethyl) morpholine hydrochloride afforded 7. The structures of the newly synthesized compounds were established on the basis of spectral analysis such as IR, 1H NMR, 13C NMR and Mass spectral data. The synthesized compounds were screened for their antimicrobial activity against two gram positive and gram negative bacteria and a fungus and found to possess good activity against selected strains.

A new class of heterocyclic compounds 1,3,4-thiadiazolo[3,2-a]-s-triazine have been synthesized as schiff’s base of 1,3,4- thiadiazole mix with ammonium acetate and various aromatic aldehyde treated in MW irradiation at 480 W. Reaction is based on microwave mediate multi-component reaction (MCRs). The structures of these compounds have been elucidated by spectral (IR, NMR & Mass) analysis. The title compounds were then evaluated for their in-vitro microbial activity against 2 gram –Ve bacteria (E.coli, K. pneumoniae), 2 gram +Ve bacteria (S.aerues, B.subtilis) and 1 fungal specie (A.niger). The some newly synthesized compounds have shown promising antimicrobial activity.

The novel metal chelates of 2-(8-quinolinol-5-yl)–methyl amino-5 -phenyl-1, 3, 4-thiadiazole (1) has been synthesized and their antimicrobial properties were evaluated. These compounds were synthesized by reaction of 2-(8-quinolinol-5-yl)–methyl amino-5 -phenyl-1, 3, 4-thiadiazole (1) with metal acetate and characterized using IR, 1H-NMR and elemental analysis. The synthesized compounds were screened for their in vitro antimicrobial activity against microorganism P. Expansum. B. Thiobromine, Nigras pora Sp. T. roseum, A. Niger, B. megaterium, S. aureus, P. aeruginosa and E. coli. All of the compounds are active against the microorganism in which some are exhibited moderate to good activity, whereas some were less active.

2 (H/substituted)-4-aryl-5H,6H, 7-arylimino-1,2,3,5,6-thiatetraazepines (6) have been obtained by basification of 2-(H/substituted)-4-aryl-5H,6H-7-arylmino-1,2,3,5,6-thiatetraazepine monohydrochloride (5).  The latter were synthesized by the interaction of N-aryl-S-chloro isothiocarbamoyl chloride (4) and 1-(H / substituted)-3-aryl-dihydroformazan (3), which were prepared initially by the condensation of aryl acid hydrazide (1) and hydrazine hydrate or substituted hydrazine (2). Compound (6) on benzoylation with benzoyl chloride and excess 10 % sodium hydroxide solution afforded benzoyl derivatives (7) and on boiling with aqueous ethanolic sodium hydroxide solution isomerizes into corresponding 1, 2, 3, 5, 6-pentaazepines (8).  The structures of all the synthesized compounds were established on the basis of elemental analysis, equivalent weight determination, spectral analysis like IR, 1H-NMR and Mass.  These newly synthesized compounds (6) were screened for their antifungal and antibacterial activity.