H6P2W12O62.24H2O Supported on Silica: A Powerful and Reusable Catalyst for the Synthesis of 4-Arylidene-2-Phenyl-5(4)-Oxazolones (Azlactones)

A simple, efficient and ecofriendly one-pot synthesis protocol has been developed for the synthesis of 4- arylidene-2-phenyl-5(4)-oxazolones (azlactones) by using an efficient and recyclable solid acid silica-supported H6P2W18O62.24H2O catalyst from a condensation of aldehydes, hippuric acid and acetic anhydride in toluene. The reaction using 0.4WDSiO2 catalyst was carried out under mild conditions with very high yields of up to 89%-93%. The heterogeneous reaction conditions provided a very simple, environmentally friendly, clean, economical and selective protocol for the preparation of these compounds. The catalyst is easily recycled and reused without loss of the catalytic activity.