Synthesis of the marine furanoditerpene (−)-marginatone

A synthesis of the marine labdane furanoditerpene (−)-marginatone has been accomplished by a short sequence of reactions starting from (+)-coronarin E . The key step is the stereocontrolled-intramolecular electrophilic cyclisation of the (+)-dihydrocoronarin E , to the tetracyclic marginatane skeleton , which is subsequently functionalized by allylic oxidation to give . As (+)-coronarin E was previously synthesized from (−)-sclareol , the herein reported preparation constitutes the first formal total synthesis of (−)-marginatone , by which its absolute configuration has been confirmed.