Synthesis of (+)-zerumin B using a regioselective singlet oxygen furan oxidation.

A short and efficient synthesis of the antitumor diterpenoid (+)-zerumin B has been accomplished starting from (+)-sclareolide. At the heart of the synthetic strategy lies the regioselective formation of the alpha-substituted gamma-hydroxybutenolide moiety of zerumin B. This was achieved by means of a [1,4] O-->C triisopropylsilyl migration followed by singlet oxygen (1 O 2) oxidation of the resulting 2-triisopropylsilyl-3-(alpha-hydroxy)alkylfuran.