New cytotoxic diterpenylnaphthohydroquinone derivatives obtained from a natural diterpenoid Original Research Article

Diterpenylquinone/hydroquinone derivatives were prepared through Diels–Alder cycloaddition between natural myrcecommunic acid or its methyl ester and p-benzoquinone (p-BQ), using BF3·Et2O as catalyst or under microwave (Mw) irradiation. Acetyl, methyl and benzyl derivatives of several diterpenylnaphthohydroquinone were prepared from cycloadducts following two basic synthetic strategies, either protection before aromatisation or viceversa. Some of them were further functionalised at the B-ring of the decaline core. Most of the new compounds were evaluated and some of them resulted cytotoxic against several tumour cell lines with IC50 values under the μM level.