Hanan A. Mohamed

Design and synthesis of new 4-pyrazolin-3-yl-1,2,3-triazoles and 1,2,3-triazol-4-yl-pyrazolin-1-ylthiazoles as potential antimicrobial agents.

New pyrazolyl-1,2,3-triazoles and 1,2,3-triazol-4-yl-pyrazolylthiazoles were synthesized through multi step reactions using 1-tolylyl-4-acetyl-5-methyl-1,2,3-triazole as a precursor. All the newly synthesized compounds were characterized by spectral and elemental analyses. The structure of 11b was evidenced by X-ray crystallographic study. The newly synthesized compounds were evaluated for their antimicrobial activities and also their minimum inhibitory concentration (MIC) against most of test organisms was performed. Amongst the tested compounds 5a, 5c, 11b and 11c displayed excellent antimicrobial activity.

Synthesis, anti-HSV-1, and cytotoxic activities of some new pyrazole- and isoxazole-based heterocycles

Ethyl 2,4-dioxo-4-(p-chloro)phenylbutyrate 2 obtained by condensation of 4-chloroacetophenone with diethyl oxalate was converted to 5-(4-chlorophenyl)-1-phenyl-1H-pyrazole-3-carbohydrazide 5 and 5-(4-chlorophenyl)isoxazole-3-carbohydrazide 6 in good yields. Treatment of 5 or 6 with phenylisothiocyanate and reaction of the resulting thiosemicarbazide 7 or 8 with chloroacetic acid and 4-fluorobenzaldehyde, phenacyl bromides gave the corresponding 4-thiazolidinone 9 or 10 or 1,3-thiazoles 11 or 12, respectively. While the intramolecular cyclization of 7 or 8 in concentrated sulfuric acid afforded 1,3,4-thiadiazoles 13 or 14. The reactivity of hydrazide 5 or 6 towards fluorinated aldehyde, hydrazonoyl chloride, and β-ketoester was studied to give fluorinated hydrazones, bis-hydrazones, and pyrazoles 15–23. The newly synthesized compounds were screened for their antiviral activity, and compound 19 reduced the number of viral plaques of Herpes simplex type-1 (HSV-1) by 69%. The detailed synthesis and spectroscopic and biological data are reported.Graphical abstract

Utility of 2,4-dioxoesters in the synthesis of new heterocycles

This review deals with synthesis and reactions of 2,4-dioxoesters. Some of these reactions have been applied successfully to the synthesis of biologically important compounds. The data published over the last years on the methods of synthesis and chemical properties of 2,4-dioxoesters are reviewed here for the first time.

Azolylthiadiazoles and benzazolylthiadiazoles

Several thiadiazoles exhibit diverse biological properties such as antimicrobial (1), antitubercular (2), anti-inflammatory (3) and anticonvulsant (4, 5) behavior. The linkage of a thiadiazole ring with different azole and benzazole moieties by one single covalent bond gives rise to a class of heterocyclic systems known as azolylthiadiazoles that also have diverse biological activities. For example, megazole “2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole” has a broad spectrum of antiprotozoan and antibacterial activities (6); 1,3,4-thiadiazole-2,5-dipyrroles are useful in antistatic packaging, sensors and moldings (7); and 5-(5-hydroxy-3-methyl-2oxoimidazolidin-1-yl)-N ,N-dimethyl-1,3,4-thiadiazole-2-sulfonamide is useful as a herbicide (8). The chemistry of azolylpyrazoles (9), but not the chemistry of azolylthiadiazole, has been previously reviewed, despite the versatility of the latter compounds. In this review, the azolylthiadiazole systems have been classified according to the type of the azole nucleus linked to thiadiazole.

Direct Routes to Thiazolotriazoles by Cyclization

Abstract Methods for the preparation of various fused thiazolotriazoles were reviewed here for the first time. The main two isomers of fused thiazolotriazoles are thiazolo[3,2-b][1,2,4]triazole and thiazolo[2,3-c][1,2,4]triazole. Some medicinal applications of thiazolotriazoles are reported. GRAPHICAL ABSTRACT

Novel Antimicrobial Agents: Fluorinated 2-(3-(Benzofuran-2-yl) pyrazol-1-yl)thiazoles

A new series of 2-pyrazolin-1-ylthiazoles 8a–d and 13–16 was synthesized by cyclization of N-thiocarboxamide-2-pyrazoline with different haloketones and 2,3-dichloroquinoxaline. The structures of the new compounds were confirmed by elemental analyses as well as NMR, IR, and mass spectral data. The newly synthesized compounds were evaluated for their antimicrobial activities, and also their minimum inhibitory concentration (MIC) against most of test organisms was performed. Amongst the tested ones, compound 8c displayed excellent antimicrobial activity.

Imidazobenzothiazoles: synthesis and application

This review article focuses on the synthesis of various types of imidazobenzothiazoles, which are potentially useful for the development of biologically active heterocycles. The synthetic methods are simple and practical and are conceivably applicable to analogous heterocyclic systems possessing nitrogen and sulfur. Also, some commercial applications of these compounds are reported as well.

Synthetic strategies for thiazoloquinoxalines and their applications

The current review article represents a survey of the literature covering the synthetic strategies leading to thiazoloquinoxalines for the first time. The review is divided into four parts discussing four groups of thiazoloquinoxalines classified based on the type of fusion between the thiazole and quinoxaline nuclei.

Synthetic access to imidazo[2,1-b]thiazoles

The current review article represents a survey covering the synthetic strategies leading to imidazo[2,1-b]thiazoles since 1980. The review is classified according to nature of starting precursor either 2-aminothiazoles or 2-mercaptothiazoles.

Pyrazolothiazoles: Synthesis and Applications

Abstract Methods for the preparation of various fused pyrazolothiazoles were reviewed here for the first time. The main types of fused pyrazolothiazole are pyrazolo[5,1-b]thiazoles, pyrazolo[3,4-d]thiazoles, and pyrazolo[4,3-d]thiazoles. Some research and industrial application of pyrazolothiazoles are reported. GRAPHICAL ABSTRACT