Enantiospecific Semisynthesis of Puupehedione-Type Marine Natural Products.

An enantiospecific semisynthesis of puupehedione was achieved from sclareolide in only 7 steps with an overall yield of 25%. The key drimanal trimethoxystyrene skeleton was constructed by the palladium-catalyzed cross-coupling reaction of an aryl iodine and a drimanal hydrazone. An in situ CAN-oxidation/intramolecular oxa-Stork-Danheiser transposition tandem reaction was used as a powerful tool to install concurrently the C and D rings of puupehedione in a one-pot fashion. Its applicability was also showcased by the semisynthesis of puupehenone and puupehenol.