Mohamed Gaber Marei

Synthesis and Antibacterial Activities of Novel Imidazo[2,1-b]-1,3,4-thiadiazoles

2-Amino-5-(2-aryl-2H-1,2,3-triazol-4-yl)-1,3,4-thiadiazoles 2-4 have been synthesized by the reaction of 2-aryl-2H-1,2,3-triazole-4-carboxylic acids 1 with thiosemicarbazide. Their reaction with phenacyl (p-substituted phenacyl) bromides led to formation of the respective 6-aryl-2-(2-aryl-2H-1,2,3-triazol-4-yl)imidazo[2,1-b]-1,3,4-thiadiazoles 5. Reactivity of the latter fused ring towards reaction with different electrophilic reagents afforded the corresponding 5-substituted derivatives 6-8. The structure of the above compounds was confirmed from their spectral characteristics. Some of these compounds were found to possess slight to moderate activity against the microorganisms Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and Escherichia coli.

A NEW SYNTHESIS OF 4H-THIOPYRAN-4-THIONES FROM ACETYLENIC β-DIKETONES

Abstract 2,6-Diaryl-4H-thiopyran-4-thiones have been synthesized in excellent yields by the reaction of 1-aryl-5-phenyl-4-pentyne-1,3-diones with phosphorus pentasulfide in dry pyridine at room temperature and were converted into the corresponding hydrazones and oximes. Their oxidation affords the respective. 4H-thiopyran-4-one sulfoxides or sulfones. The structure of the above compounds was confirmed from their spectral characteristics.

A NEW SYNTHESIS OF 6-THIATHIOPHTHENES FROM ACETYLENIC β-DIKETONES

Abstract A new method for the synthesis of 2,5-diaryl-6-thiathiophthenes is described involving the reaction of 1,5-diarylpent-1-yne-3,5-diones with phosphorus pentasulfide. The reaction of 3-chloro-6-thiathiophthenes with hydrazine hydrate gave pyrazole derivatives. Nitration of the 6-thiathiophthenes afforded the corresponding 4-nitro-1-oxa-6,6a-dithia-2-azapentalenes.

Nickel(II) and copper(II) complexes of 5-aryl-2-phenyl-6H-pyrazolo-[1,5-c]pyrimidine-7-thiones

SummaryNiII and CuII complexes of 5-aryl-2-phenyl-6H-pyrazolo-[1,5-C]pyrimidine-7-thiones were prepared and characterized by elemental analysis, i.r, u.v.-vis. spectra, molar conductivities and magnetic measurements. Spectral and magnetic data suggest a square-planar structure for nickle(II) complexes.

Synthesis and ligating behaviour of 5-heteroaryl-1-phenylpent-1-yne-3,5-diones

SummaryEthyl phenylpropiolate reacts with α-acetylfuran and α-acetylpyridine in the presence of NaOEt to yield the respective acetylenic β-diketones as well as 2-heteroaryl-6-phenyl-4H-pyran-4-ones as minor products. Copper(II), nickel(II) and cobalt(II) complexes of the title compounds were prepared and characterized by elemental analysis, i.r., u.v.-vis., e.s.r. spectra, electrical conductivity and magnetic measurements. The data suggest square-planar and octahedral structures for the copper(II) and cobalt(II) complexes, respectively. The nickel(II) complexes appeared to be either square-planar or octahedral depending upon the nature of the ligand.

Chemistry of Pent-4-yne-1,3-diones (Acetylenic β-diketones) as Precursors for Heterocyclic Compounds

Abstract The pent-4-yne-1,3-diones (acetylenic β-diketones) have different reactive functionalities which let them attractive, particularly as precursors for heterocyclic compounds. This chapter surveyed the chemistry of their synthesis, which has started with the appropriate propiolic acid derivatives or acetylenic aldehydes. They have been converted to five-, six-, and seven-membered heterocyclic rings in addition to fused bicyclic compounds such as dithiepine, pyrrolo[1,2,3]triazole, thiathiophthene, pyrazolo[1,3]thiazines, pyrazolo[1,5-c]pyrimidines, and metal complexes. The spectroscopic properties have also been reviewed.