D,L‐Proline‐Catalyzed One‐Pot Synthesis of Pyrans and Pyrano[2,3‐c]pyrazole Derivatives by a Grinding Method under Solvent‐Free Conditions

Abstract

D,L‐Proline was found to efficiently catalyze the one‐pot condensation of aromatic aldehydes, malononitrile, and dimedone (1,3‐cyclohexanedione or 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one) 2‐Amino‐3‐cycano‐4‐aryl‐7,7‐dimethyl‐5,6,7,8‐tetrahydrobenzo[b]pyrans and 6‐amino‐5‐cyano‐4‐aryl‐1,4‐dihydropyrano[2,3‐c]pyrazoles were synthesized by a grinding method under solvent‐free conditions. The reaction proceeded cleanly at room temperature to afford the products in good yields.

Keywords:

• 1,3‐cyclohexanedione
• 1,4‐dihydropyrano[2,3‐c] pyrazole
• dimedone
• D,L ‐proline
• grinding method
• malononitrile
• 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one
• solvent free
• 5,6,7,8‐tetrahydrobenzo[b]pyrans