SEARCH Articles Figures Tables Alder intermolecular Catalysis intermolecular Diels acid Diels-Alder catalysis Diels-Alder reaction acids Diels-Alder reactions Lewis acid catalysis Diels-Alder reactions catalysis Intermolecular Diels—Alder Lewis acids Diels-Alder reaction Lewis acids acid catalysis Lewis acids, catalysis Lewis catalysis Lewis reactions