Synthesis of some novel pyrazolo[3,4-b]pyridine and pyrazolo[3,4-d]pyrimidine derivatives bearing 5,6-diphenyl-1,2,4-triazine moiety as potential antimicrobial agents.

Chemistry of α-oxoesters: a powerful tool for the synthesis of heterocycles.

Some new sulfur-nitrogen heterocyclic systems such as 1,3-thiazoles, 1,3,4-thiadiazoles, 1,2,4-triazoles and 1,3-thiazines incorporating acridine and 1,2,3,4-tetrahydroacridine moieties were synthesized via heterocyclization of the key intermediate 4-(acridin-9-yl)-1-(1,2,3,4-tetrahydroacridin-9-ylcarbonyl)thiosemicarbazide. Structures of the new comp-ounds were established by elemental analyses and spectral data. All the products were also screened in vitro for their antimicrobial activity.

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Synthesis and antimicrobial activity of some new 1,3-thiazoles, 1,3,4-thiadiazoles, 1,2,4-triazoles and 1,3-thiazines incorporating acridine and 1,2,3,4-tetrahydroacridine moieties

Synthesis, characterization and antibacterial screening of some novel 1,2,4-triazine derivatives

(Me3Si)2CNN isomerizes upon addition of traces of [Me3Si]+ ions to give (Me3Si)2NNC, which then undergoes an unusual trimerization reaction to give exclusively 4-diazenyl-3-hydrazinylpyrazole. As catalyst the isonitrilium ion, [(Me3Si)2NNC(SiMe3)]+, was identified and fully characterized. Experiments and computations indicate a three-step reaction including isomerization of diazomethane, a C–C or N–C coupling, and a formal cycloaddition reaction. The kinetics and thermodynamics are discussed on the basis of DFT calculations.

Catalytic Trimerization of Bis-silylated Diazomethane

Condensation 4-oxo-4H-chromene-3-carboxaldehydes (1a,b) with acid hydrazine-carbodithioic acid and/or thiocarbohydrazide afforded hydrazonecarbodithioic acid 2, monothiocarbohydrazone 3a,b and bisthiocarbohydrazone 4, respectively. Heterocyclization of 2–4 via reaction with oxygen, sulfur and/or halogen reagents in different media yielded pyridazinethione 5; 1,3-thiazoles 7; pyrazoles 9–12; 1,2,4-thiadiazoles 8,13,14, and 23; 1,2,4-triazolethiones 15–17; 1,2,4-triazinethiones 18–22; imidazolethione 24 and pyrimidinethione 25 derivatives. Antifungal activity was screened for some the new synthesized compounds. Formulations of all products have been deduced by elemental analysis and spectral data (IR, 1H NMR and Mass spectroscopy).

A. Z. El-Fauomy

Papers

Synthesis of Bioactive 4-Oxo-4H-Chromenes Bearing Heterocyclic Systems from Hydrazonecarbodithioic Acid and Thiocarbohydrazone