A Novel Stereocontrolled Approach to Eudesmanolides: Total Synthesis of (±)-Gallicadiol and (±)-Isogallicadiol

A novel approach for the stereocontrolled synthesis of eudesmanolides was developed based on a quasi-biomimetic strategy starting from a
functionalized oxabicyclic template, as shown above, by which the first total syntheses of gallicadiol (6) and isogallicadiol (7) were achieved.
The key elements of the synthesis include:  (1) a facile and stereospecific synthesis of a functionalized epoxy aldehyde intermediate; (2) a
mild Lewis acid-mediated stereoselective ene cyclization; and (3) a stereocontrolled γ-lactonization.