[摘要]：A new class of base-catalyzed Diels-Alder reactions of 2H-pyran-2,5-diones has been developed using catalytic amt. of dicyclohexylmethylamine in tert-Bu alc. This method has been successfully employed for construction of the tricyclic core (I) of basiliolide B at room temp. with good yields and exclusive endo selectivity.
