4-Acetyl-2-phenyl-1,2,3-triazole (1) was synthesized from 2-phenyl-1,2,3-triazolocarboxylic acid and used as stating material for preparation of substituted chalcones 2a～2e. These chalcones were converted into corresponding 4,5-dihydropyrazole derivatives 4a～4j through [3＋2] 1,3-dipolar cycloaddition with nitrileimines, generated in situ from hydrazonyl halides (3a, 3b) in the presence of Et₃N. The structures of these compounds were characterized by IR, ¹H NMR, mass spectra, and elemental analysis. The structure of 4i was comfirmed by X-ray diffraction analysis.

Key words: synthesis; chalcone, 1,2,3-triazole, 4,5-dihydropyrazole, crystallographic structure