Sodium salt of 3‐hydroxy‐1‐(1‐aryl‐5‐methylpyrazolyl)propenone derivatives was used as a precursor for synthesis of various fused azolopyrimidine ring systems as pyrazolopyrimidines, triazolopyrimidines, and pyrimidobenzimidazoles following many procedures. The identity of the prepared compounds was elucidated by their spectral data and elemental analyses. The in vitro antimicrobial activity of 13 new compounds was evaluated, and many derivatives showed good to moderate activity.

Aminohydrazide cross-linked chitosan (CLCS) and its MWCNTs (CLCS/MWCNTs) were formulated and utilized as a potent ecofriendly basic heterogeneous biocatalyst under ultrasonic irradiation for synthesis of two novel series of benzil bis-aryldiazenylthiazoles and benzil bis-arylhydrazonothiazolones from the reaction of benzil bis-thiosemicarbazone with 2-oxo-N′-arylpropanehydrazonoyl chlorides and ethyl 2-chloro-2-(2-phenylhydrazono) acetates, respectively. The chemical structures of the newly synthesized derivatives were elucidated by spectral data and alternative methods, where available. Additionally, their yield % was estimated using a traditional catalyst as TEA and green recyclable catalysts as CLCS and CLCS/MWCNTs composite in a comparative study. We observed that, under the same reaction conditions, the yield % of the desired products increased by changing TEA to CLCS then to CLCS/MWCNT from 72–78% to 79–83% to 84–87%, respectively. The thermal stability of the investigated samples could be arranged as CLCS/MWCNTs composite > CLCS > chitosan, where the weight losses of chitosan, CLCS and CLCS/MWCNTs composite at 500 °C were 65.46%, 57.95% and 53.29%, respectively.

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Sodium 1‐aryl‐3‐(3‐(ethoxycarbonyl)‐5‐methyl‐1H‐pyrazol‐4‐yl)‐3‐oxoprop‐1‐en‐1‐olate was used as precursor for the preparation of some novel derivatives of various fused azolotriazine ring systems via coupling reactions with hetaryldiazonium salts. Hydrazinolysis of the latter products yielded the corresponding pyrazolopyridazine derivatives. The structures of the products were established by their spectral data and elemental analyses. The antibacterial and antifungal activities of some of the new products were also evaluated.

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