Regioselective 1,3‐dipolar cycloaddition of nitrilimines (generated in situ from dehydrohalogenation of the corresponding hydrazonoyl halides by the action of triethylamine) with 4‐arylidene‐1‐aryl‐2‐phenyl‐1H‐imidazol‐5(4H)‐one 3 afforded the corresponding spiro[4,4]nona‐2,8‐dien‐6‐one 4. The reaction was carried out in dry benzene under reflux temperature. Refluxing in acetic acid, 4a was converted to its respective N‐phenylpyrazole‐5‐carboxamide 8. The structures of prepared compounds were established by elemental analyses and spectral data (IR, MS, 1H, and 13C NMR). © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:131–136, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20666