Taiwaniadducts are a class of terpenoids with impressive Diels-Alder cycloadduct scaffold.The first total syntheses of taiwaniadducts B,C,and D have been accomplished.Two diterpenoid segments were prepared with high enantiopurity,both through Ir-catalyzed asymmetric polyene cyclization.A sterically demanding intermolecular Diels-Alder reaction promoted by Er(fod)3 assembled the scaffold of taiwaniadducts B and C.A carbonyl-ene cyclization forged the cage motif of taiwaniadduct D at a late stage,providing over 200 mg of this compound.