Polypyrrole/Fe 3 O 4 /CNT as a recyclable and highly efficient catalyst for one‐pot three‐component synthesis of pyran derivatives

Polypyrrole (PPY)/Fe 3 O 4 /CNT has been synthesized and characterized by FT‐IR, TEM and SEM techniques and its catalytic activity has been evaluated in the synthesis of several series of pyran derivatives. Tetrahydrobenzo[ b ]pyranes, 4H‐pyran‐3‐carboxylates, 4H,5H‐pyrano[3,2‐ c ]chromenes and dihydropyrano[2,3‐ c ]pyrazoles have been successfully prepared from one‐pot three‐component condensation of aldehyde, malononitrile and active methylene‐containing compounds (dimedone /ethyl acetoacetate/4‐hydroxycoumarin/3‐methyl‐2‐pyrazoline‐5‐one) using PPY/Fe 3 O 4 /CNT as a new and reusable heterogeneous catalyst. The present method offer several advantages such as; high yields of products, short reaction times, easy work‐up procedure and easy separation of the catalyst from the reaction mixture due to its magnetic character. Furthermore, chemoselective synthesis of bis‐benzo[ b ]pyran from terephthalaldehyde can be achieved by this method.