A synthesis is described that leads from cyclopentadiene through 5-norbornen-2-one to the monosubstituted cyclopentenone 5; a vinyl substituent is attached by the reaction of a cuprate, and the enolate intermediate is trapped as the silyl enol ether 4, which is converted to 19, a product with the 10-carbon framework and stereochemistry of the secoxyloganin aglucone, and with all functional groups differentially protected and in the correct oxidation state. Explorations of the cuprate reaction required to convert the cyclopentenone 5 to the siloxycyclopentene 4 and of the reactions required for the oxidative cleavage of 4 reveal problems with these reactions when they are applied to compounds that are cyclopentane derivatives. The resolution of these problems leads to reaction sequences that proceed with high yields and excellent diastereoselectivity. Keywords: synthesis, secoxyloganin, vinyl cuprate, oxidative cleavage.