D,L-proline-catalyzed one-pot synthesis of pyrans and pyrano[2,3-c]pyrazole derivatives by a grinding method under solvent-free conditions

摘要

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.