Enantioselective syntheses of isoaltholactone, 3-epi-altholactone, and 5-hydroxygoniothalamin

GRAPHICS A flexible enantioselective route to highly functionalized alpha,beta-unsaturated delta-lactones has allowed for the syntheses of the styryllactones: isoaltholactone, 3-epi-altholactone, and 5-hydroxygoniothalamin in 10%, 5%, and 13% overall yields from furfural, respectively. This approach derives its asymmetry by applying the Sharpless catalytic asymmetric dihydroxylation to vinylfuran. The resulting diols are produced in high enantioexcess and can be stereoselectively transformed into alpha,beta-unsaturated delta-lactones via a short highly diastereoselective oxidation and reduction sequence.