Transformation of α-Santonin into 7-Hydroxyeudesmanes

Autoxidation of (11S)-12-hydroxy-7α-eudesmane-3,6-dione in the presence of p-toluenesulfonic acid gave 6,12-epoxy-11β-eudesma-4,6-dien-3-one, which was oxidized with m-chloroperoxybenzoic acid to give (11R)-7α,12-dihydroxyeudesm-4-ene-3,6-dione. Transformation of some other 12-hydroxyeudesman-6-ones into 7,12-dihydroxyeudesman-6-ones was also examined.