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

ome 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.