Synthesis and Molluscicidal Activity of New Cinnoline and Pyrano [2,3‐ c ]pyrazole Derivatives

2‐(3‐Hydroxy‐5,5‐dimethylcyclohexylidene)malononitrile 5 undergoes an azo coupling reaction with aryldiazonium salts to afford 3‐amino‐2‐aryl‐6,6‐dimethyl‐8‐oxo‐2,6,7,8‐tetrahydrocinnoline‐4‐carbonitriles 7 . Upon reflux in acetic acid, these compounds were acetylated to give the cinnoline derivatives 9 . The pyrazolones 10a, b react with 3‐furfurylidene‐ and 3‐thienylidene‐malononitrile derivatives 11a, b to afford the pyrano[2,3‐ c ]pyrazole derivatives 13a–d . These newly synthesized compounds show generally a moderate molluscicidal activity to Biomphalaria alexandrina snails.