A synthesis of (±)-cryptojaponol and (±)-taxodione

Programmed Polyene Cyclization Enabled by Chromophore Disruption

A new polyene cyclization strategy exploiting β-ionyl derivatives was developed. Photoinduced deconjugation of the extended π-system within these chromophores unveils a contrathermodynamic polyene that engages in a Heck bicyclization to afford [4.4.1]-propellanes. This cascade improves upon the limited regioselectivity achieved using existing biomimetic tactics and tolerates both electron-rich and electron-deficient (hetero)aryl groups. The utility of this approach was demonstrated with the diverted total synthesis of taxodione and salviasperanol, two isomeric abietane diterpenes that were previously inaccessible along the same synthetic pathway.

Total synthesis and biological evaluation of an antifungal tricyclic o-hydroxy-p-quinone methide diterpenoid

A convergent route has been developed to synthesize an antifungal tricyclic o-hydroxy-p-quinone methide diterpenoid and analogues. A Li/naphthalene-mediated reductive alkylation was employed for coupling β-cyclocitral and the corresponding benzyl chloride, while a BBr3-mediated one-pot bis-demethylation and intramolecular Friedel-Crafts alkylation was used to assemble the tricyclic molecular skeleton. The structure-activity relationship of the diterpenoid was assessed on the basis of antiproliferation assays of the natural product and analogues against strains of pathogenic yeasts and filamentous fungi.