Integral Stereocontrolled Synthesis of a Spiro-norlignan, Sequosempervirin A: Revision of Absolute Configuration

A novel synthetic path to sequosempervirin A was established by employing a samarium diiodide promoted intramolecular Barbier-type reaction of the lactonic iodide, In which the key structural feature, a spiro[4.5]decane ring system, could be constructed by controlling the stereochemistry of the hydroxyl group at the 8-position. The absolute configuration of natural sequosempervirin A was revised to be 4S based on this synthesis.