Y. A. Ammar

Synthesis and Antimicrobial Activities of Some Novel Quinoxalinone Derivatives

Department of Chemistry, Faculty of Science, Al-Azhar University at Assiut, Assiut 71524, EgyptFax: 002(088)325436, E-mail: m_elgaby@hotmail.comReceived: 29 April 2000 / Accepted: 13 June 2000 / Published: 18 June 2000Abstract: Condensation of 4-benzoyl-1,2-phenylenediamine with sodium pyruvate in aceticacid furnished two products which were identified as 6-benzoyl and 7-benzoyl-3-methyl-2(1H)quinoxalinones ( 1a ,b ). Fusion of 1a with aromatic aldehydes furnished the styryl de-rivatives 2a -c. Alkylation of 1a ,b with dimethyl sulphate or ethyl chloroacetate produced theN-alkyl derivatives 3a ,b and 4a ,b . Hydrazinolysis of the ester derivative 4a with hydrazinehydrate afforded the hydrazide derivative 5 which underwent condensation with aldehydes togive the corresponding hydrazone derivatives 6a ,b . In addition, chlorination of 1a withthionyl chloride afforded the 2-chloro derivative 7 which was subjected to reaction with s o-dium azide and n-butylamine to yield the corresponding tetrazolo (8) and n-butylamino (9)derivatives, respectively. The structures of the compounds prepared were confirmed by an a-lytical and spectral data. Also, some of the synthesized compounds were screened for antim i-crobial activity.Keywords: Quinoxalinones, 4-benzoyl-1,2-phenylenediamine, antimicrobial activity.

Synthesis of some new 2-(3-pyridyl)-4,5-disubstituted thiazoles as potent antimicrobial agents.

As a part of ongoing studies in developing new potent antimicrobial agents, a series of novel 2-(3-pyridyl)-4,5-disubstituted thiazoles was efficiently synthesized and characterized by spectral and elemental analyses. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against ten bacterial and five fungal human pathogenic strains using the disc diffusion assay. Among the synthesized compounds, 5-acetyl-4-methyl-2-(3-pyridyl)thiazole (5) exhibited twofold antibacterial activity of ampicillin in inhibiting the growth of Staphylococcus epidermidis (MIC 0.24 μg/mL) and also showed equipotent antifungal activity with amphotricin B against Geotricum candidum (MIC 0.48 μg/mL). From structure-activity relationship (SAR) point of view, increasing the size of the substitutions either at position 4 or 5 on the thiazole nucleus decreased the antimicrobial activity.

Synthesis and radiation stability of novel biologically active sulfur compounds derived from 1,2-bis(4-amino-5-mercapto-s-triazol-3-yl)ethane

Some novel 1,2-bis(s-triazolo[3,4b][1,3,4]thiadiazino-3-yl)ethane (4-7); 1,2-bis(s-triazolo[3,4b][1,3,4]thiadiazol-3-yl)ethane (16a,b) and 1,2-bis(s-triazolo[3,4b][1,3,4]thiadiazepino-3-yl)ethane (17) were synthesized via reaction of 1,2-bis(4-amino-5-mercapto-s-triazol-3-yl)ethane (3) with different reagents. Identification of the new compounds was established by elemental analyses, IR, 1H NMR and mass spectral data. Compounds 12, 13, 16b and 17 were promising antifungal activity. The biologically active compounds 13, 16b and 17 were radioresistant retaining their structures unchanged up to 40 k Gy. Radiosterilization of these compounds in the dry state may prove to be applicable.

Some reactions with Ketene dithioacetals: Part I: Synthesis of antimicrobial pyrazolo[1,5-a]pyrimidines via the reaction of ketene dithioacetals and 5-aminopyrazoles

Pyrazolo[1,5-a]pyrimidines were synthesized via the reaction of ketene dithioacetals and 5-aminopyrazoles. The antibacterial and antifungal activities of some selected compounds are also reported.

Synthesis, characterization and DFT study of methoxybenzylidene containing chromophores for DSSC materials.

Novel tricyanovinyl derived from hydrazones have been prepared by the reaction of tetracyanoethylene and phenylethylidene hydrazone, and these dyes showed absorption in the region of 539-650 nm. The dyes showed pronounced solvatochromic effects as the polarity of the solvents changed. The torsion in E isomer is smaller than Z and azo isomers of MBD1 and MBD2. The HOMOs are delocalized on whole of the molecule while LUMOs are distributed on the tricarbonitrile. The LUMO energies are above the conduction band of TiO(2) and HOMOs of the dyes are below the redox couple of MBD1 and MBD2. The HOMO energies, LUMO energies and HOMO-LUMO energy gap of MBD1 and MBD2 are almost same. The absorption spectra of both the dyes in different solvents are approximately same except in cyclohexane.

SYNTHESIS AND RADIATION STABILITY OF NOVEL THIAZOLOPYRIMIDINES WITH EXPECTED ANTIFUNGAL ACTIVITY

Abstract A number of thiazolopyrimidines (II–VII) were prepared through interaction of 6-methyl-4(4′-chlorophenyl)-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl ester (Ia) with many reagents. The antifungal activity of all prepared compounds have been determined using Dithane M-45 as a standard fungicide. Some compounds showed a high fungicidal activity equivalent to that of the standard towards Aspergillus niger and Aspergillus ochraceus. Also some biologically active compounds were subjected to gamma irradiation and the structures are stable.

Aminoacids in the Synthesis of Heterocyclic Systems: The Synthesis of Triazinoquinazolinones, Triazepinoquinazolinones and Triazocinoquinazolinones of Potential Biological Interest

A number of novel triazinoquinazolinones (5b,c and 8), triazepinoquinazolinones(5a, 6b, 7 and 9) and triazocinoquinazolinones (6a and 10) were obtained via nucleophilic interaction of 3-aminoquinazolinone derivatives 3 with different reagents.

SYNTHESIS AND ANTIFUNGAL ACTIVITY OF SOME NEW MISCELLANEOUS S-TRIAZOLES

Abstract The reaction of aryloxyacetic acid with thiocarbohydrazide under condition of fusion gave the corresponding s-triazole derivatives 2a-c. The dicyano derivatives 3, 4 were obtained via reaction of compound 2c with [bis(methylsulfanyl)methylidine]malononitrile and/or ethoxymethylenemalononitrile. Interaction of compound 2c with bromomalononitrile yielded the corresponding triazolothiadiazine derivative 5. In addition reaction of compound 2c with phenyl isothiocyanate furnished triazolothiadiazole derivative 6. Fusion of arylaminoacetic acids 8, 9 with thiocarbohydrazide afforded s-triazole derivatives 10, 11, respectively. The reaction of benzylthioacetic acid 12 with thiocarbohydrazide yielded the triazole derivative 13, When cyanoacetic acid 14 was reacted with thiocarbohydrazide the pyrazolotriazole derivative 16 was obtained. Some of the obtained compounds showed remarkable antifungal activity comparable to the fungicide Mycostatine.

A novel synthesis of dibenzo[c, f]chromenes, dibenzo[c, h]chromenes and benzo[7,8]chromeno[3,4-f]isoindoles as antimicrobial agents

Naphtho[2,1-b]pyranone (3) was allowed to react with arylmethylenemalononitriles to yield 4-amino-5-oxo-2-aryl-5H-dibenzo[c,f]chromene-3-carbonitriles (4a,b); with ethyl 3,4-dichlorobenzylidene cyanoacetate to furnish dibenzo[c,f]chromene (5) and with elemental sulfur in dioxane containing piperidine to give thieno[3,4-d]naphtho[2,1-b]pyranone (6). Similarly, naphtho[1,2-b]pyranone (7) was reacted with arylmethylenemalononitriles and elemental sulfur to furnish dibenzo[c,h]chromenes (8) and thieno[3,4-d]naphtho[1,2-b]pyranone (10), respectively. Compound 10 underwent cycloaddition with N-arylmaleimides to yield benzo[7,8]chromeno[3,4-f]isoindoles (11a-c). Some of these compounds were screened in vitro for their antimicrobial activities.

Synthesis of Some Azoles Incorporating a Sulfonamide Moiety as Anticonvulsant Agents

Many derivatives of heterocyclic compounds containing a sulfonamide thiazole moiety were synthesized through the reaction of 2‐(cyano or chloro)‐N‐(4‐(N‐thiazol‐2‐ylsulfamoyl)phenyl)acetamide with isocyanate followed by halogenated compounds, arylidene, 2‐hydroxy benzaldehydes, active methylene compounds, and heterocyclic amines. The anticonvulsant activity for 15 of the synthesized compounds was evaluated and 6 compounds showed protection against picrotoxin‐induced convulsion. 4‐(6‐Amino‐3,5‐dicyano‐4‐(4‐methoxyphenyl)‐2‐oxopyridin‐1(2H)‐yl)‐N‐(thiazol‐2‐yl)benzenesulfonamide (11b) exhibited significant anticonvulsive effects, abolished the tonic extensor phase and offered 100% protection.