Synthesis of Mono- and Sesquiterpenoids; XXIV: (-)-Homogynolide A, an Insect Antifeedant Isolated from Homogyne alpina

Abstract

(-)-Homogynolide A (1), an insect antifeedant isolated from Homogyne alpina (Compositae), was synthesized from (1R,4S,6S)-6-hydroxy-1-methylbicyclo[2.2.2]octan-2-one (7), which was readily prepared by the yeast reduction of the corresponding prochiral β-diketone. The key step was the oxy-Cope rearrangement of 6 to give 5.