| This dissertation focuses mainly on the total synthesis of sculponeatin N including asymmetric synthetic studies towards sculponeatin N. The dissertation consisted of two parts as follows:Chapter1:Total Synthesis of Sculponeatin NThe synthetic studies on the total synthesis of6,7-seco-ent-kaurane diterpenoids, including15-desoxyeffusin, longirabdolactone, maoecrystal Z, trichorabdal A, longikaurin E, maoecrystal V, and sculponeatin N have been reviewed briefly. Total synthesis of sculponeatin N, a6,7-seco-ent-kaurane diterpenoid from Isodon Sculponeatus with cytotoxic activity, has been described. The initial strategy began with the coupling reaction via palladium catalyst between diester and alkenyl iodide. We have accomplished the first total synthesis of (±)-sculponeatin N in thirteen steps with a13.9%overall yield. Key features of the current synthesis include:i) a sequential regio-and stereoselective aldol/epimerization/lactonization to produce the C-10quaternary carbon center, ii) an intramolecular Diels-Alder reaction to simultaneously construct the B and C rings, and iii) a radical cyclization to assemble the D ring. In addition, attempts were made towards the synthesis of sculponeatin O.Chapter2:Asymmetric Synthetic Studies towards Sculponeatin NThe literature on the asymmetric Diels-Alder recation has been briefly reviewed. Asymmetric synthetic studies towards sculponeatin N was conducted based on our completed total synthesis of (±)-sculponeatin N. Both asymmetric Diels-Alder reaction and asymmetric double-Michael addition have been attempted in order to construct the A ring of the desired absolute configurations; however, satisfactory results have not been obtained so far. |
