[reaction: see text] The alpha-hydroxycyclopentenone core structure of terpestacin has been prepared in a model system through an allene ether Nazarov cyclization of an alkylidene-gamma-butyrolactone followed by regio- and stereoselective alkylation reactions. The stereochemistry at C15 (terpestacin numbering) has been used to control stereochemistry at C1 and at C23. The use of E-alkylidene-gamma-butyrolactones extends the scope of the cationic cyclopentannelation reaction.