Oxidative cyclization of a seco-cladiellane diterpenoid

A short and efficient synthesis of a diterpenoid with a 1,2-seco-cladiellane carbon skeleton is described, starting from geraniol and carvone. One-step oxidative cyclization with a RuO2/NaIO4 system leads to two diastereomeric, bicyclic triols, which contain six stereogenic centers and will be helpful in the synthesis of eleutherobin. The stereochemical outcome of this cyclization has been determined by X-ray analysis.