Intramolecular Diels-Alder cycloaddition of enantiomerically enriched triene 16 could be attained under thermal conditions resulting in the formation of octahydronaphthalene derivatives 17–20, one of which wn converted into PI-201 (1), a new platelet aggregation inhibitor.
The thermal intramolecular Diels–Alder cycloaddition of a 2 : 1 mixture of ethyl (2E,8E and Z, 10E,13R)-13-(t-butyldimethylsilyl) oxy-2,10-dimethyl-2,8,10-pentadecatrienoate provided four diastereomeric cycloadducts. Deprotection of one of the cycloadducts provided PI-201, a novel platelet aggregation inhibitor, as its natural form. Three stereoisomers of PI-201 were prepared from the other cycloadducts