Synthesis of 4H‐benzopyrans catalyzed by acyclic acidic ionic liquids in aqueous media

Abstract magnified image Some halogen‐free acyclic task‐specific ionic liquids (TSILs) were synthesized as novel and recyclable catalysts for the synthesis of 5‐oxo‐5,6,7,8‐tetrahydro‐4H‐benzo[b]pyrans by one‐pot three‐component condensation of aromatic aldehyde, malononitrile (or ethyl cyanoacetate), and dimedone (or 1,3‐cyclohexanedione) in water. The condensation accomplished successfully with good yields ranged from 86 to 94%. After the reaction, the products could simply be separated from the catalyst/water, and the catalyst could be reused at least 10 times without noticeably decreasing the catalytic activity. J. Heterocyclic Chem., 2010.