` One-pot synthesis of benzopyrans catalyzed by silica supported dual acidic ionic liquid under solvent-free conditions

A mild and efficient method was developed for the preparation of tetrahydrobenzo[b]pyrans through a one-pot three-component condensation of aldehydes, malononitrile and dimedone in the presence of silica supported dual acidic ionic liquid (DAIL@SiO2) as a powerful catalyst under solvent-free conditions. This procedure is characterized by mild reaction conditions, simple workup and environmental friendliness. Moreover, the catalyst could be recycled for five times with only a slight loss of catalytic activity.