Stereospecific Synthesis of Bis-Homoconduritol-A via Bicyclic Bis-Epoxide Ring Opening

Concise synthesis of bis-homoconduritol-A was performed in a stereocontrolled manner starting from cyclooctatetraene. Tricyclic endoperoxide was prepared via photooxygenation of bicyclic dibromodiene compound. The necessary key intermediate, bis-epoxide, was quantitatively synthesized from the rearrangement reaction of endoperoxide under thermal conditions. Stereoselective ring-opening reactions of the relevant bis-epoxide with H+/H2O and H+/AcCl were investigated. Ring-opening of bis-epoxide yielded bicyclic tetrol and haloester compounds. Acetylation of the bicyclic tetrol followed by removal of halogens with zinc powder in acetic acid yielded dibromo tetraacetate. The desired bis-homoconduritol-A was obtained in high yield by ammonolysis of the acetate groups by NH3. The structures of all synthesized compounds were characterized by spectroscopic methods.