title: Asymmetric total synthesis of (-)-lundurine B and determination of its absolute stereochemistry.
abstract: A total synthesis of the Kopsia tenuis alkaloid (-)-lundurine B has been achieved. A quaternary chiral carbon has been created by an asymmetric deprotonation using a symmetric spiro cyclohexanone intermediate with a chiral lithium amide. The hexacyclic skeleton was sequentially constructed through metal-mediated reactions. The absolute stereochemistry of intermediate 5 has been unambiguously established by X-ray crystallographic analysis. This is the first description of the absolute stereochemistry of Kopsia tenuis alkaloids based on chemical synthesis.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuou-ku, Chiba 260-8675 (Japan).
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakajima
authors.forename: Shigeru
authors.initials: S
authors.lastname: Arai
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishida
mesh_terms: D029062:Apocynaceae / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D011083:Polycyclic Compounds; C000590471:lundurine B
keywords: alkaloids; asymmetric synthesis; lundurine; natural products; total synthesis