Summary: A nine-step, stereoselective synthesis of 3, the right-hand half of antibiotic X- 14547A (11, is described. The key step of this synthesis is the Lewis acid catalyzed intramolecular Diels-Alder reaction of 4 which establishes the relative stereochemistry of the perhydroindene nucleus of 1.
![diethyl 2-[2-(1,3-dioxolan-2-yl)ethyl]-2-ethylpropanedioate Structure](https://image.chemsrc.com/caspic/354/64298-16-4.png)