title: Asymmetric total synthesis of (-)-stenine and 9a-epi-stenine.
abstract: A route for the asymmetric synthesis of (-)-stenine, a member of the Stemona alkaloid family used as folk medicine in Asian countries, is described. The key features of the sequence employed include stereoselective transformations on a cyclohexane ring controlled by a chiral auxiliary unit and an intramolecular Mitsunobu reaction to construct the perhydroindole ring system. By using an intermediate in the route to (-)-stenine, an asymmetric synthesis of 9a-epi-stenine was also executed. The C(9a) stereocenter in 9a-epi-stenine was installed by using a Staudinger/aza-Wittig reaction of a keto-azide precursor followed by reduction of the resulting imine. The results of this effort demonstrate the applicability of the chiral auxiliary based strategy to the preparation of naturally occurring alkaloids that contain highly functionalized cyclohexane cores.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-oka, Suita, Japan. fujioka@phs.osaka-u.ac.jp
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Fujioka
authors.forename: Kenji
authors.initials: K
authors.lastname: Nakahara
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kotoku
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ohba
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nagatomi
authors.forename: Tsung-Lung
authors.initials: TL
authors.lastname: Wang
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Sawama
authors.forename: Kenichi
authors.initials: K
authors.lastname: Murai
authors.forename: Kie
authors.initials: K
authors.lastname: Hirano
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Oki
authors.forename: Shintaro
authors.initials: S
authors.lastname: Wakamatsu
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kita
mesh_terms: D000438:Alcohols / Q000737:chemistry; D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D003510:Cyclohexanes / Q000737:chemistry; D041901:Stemonaceae / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D000470:Alkaloids; D003510:Cyclohexanes; C441784:stenine; C506365:Cyclohexane