(-)-Peninsularinone NSC676836 Peninsularinone Picras-3-ene-2,16-dione, 11,20-epoxy-15-[[(3S)-3-ethyl- 3-hydroxy-4-methyl-1-oxopentyl]oxy]-1,11,12-trihydroxy-, (1.beta.,11.beta.,12.alpha.,15.beta.)-