Base-Catalyzed Diels−Alder Reactions of 2<i>H</i>-Pyran-2,5-diones: A Mild Approach to Basiliolide B

A new class of base-catalyzed Diels−Alder reactions of 2<i>H</i>-pyran-2,5-diones has been developed using catalytic amount of dicyclohexylmethylamine in <i>tert</i>-butyl alcohol. This method has been successfully employed for construction of the tricyclic core of basiliolide B at room temperature with good yields and exclusive <i>endo</i> selectivity.