This work represents the first de novo synthetic approach to the halogenated, monocyclic monoterpenes isolated from red algae belonging to the genus Plocamium. The total syntheses of two natural products, ie, epi-plocamene D (2) and the allylic chloride 3, are presented along with an approach to the synthesis of violacene (1). A key step in the construction of the terpenoid skeleton is the Diels-Alder reaction utilizing a P-halogenated ...