Synthetic applications of homoiodo allylsilane II. Total syntheses of (-)-andrographolide and (+)-rostratone

摘要

The first total synthesis of (-)-andrographolide (1), an ent-Labdane diterpenoid lactone from Asian medicinal herb Andrographis paniculata, was achieved via the biomimetic cyclization of an epoxy homoiodo allylsilane precursor 7. Asymmetric total synthesis of (+)-rostratone (25), an antipodal Labdane diterpenoid, was also accomplished via similar biomimetic cyclization of a readily accessible epoxy homoiodo allylsilane precursor 18.