title: Stereocontrolled total synthesis of (-)-vincamajinine and (-)-11-methoxy-17-epivincamajine.
abstract: The first total syntheses of (-)-vincamajinine (5) (from Na-methyl-d-tryptophan methyl ester) and (-)-11-methoxy-17-epivincamajine (6) (from Na-methyl-6-methoxy-d-tryptophan ethyl ester) are described. The syntheses have been completed in a highly stereocontrolled manner (>98% ee). Key steps included the asymmetric Pictet-Spengler reaction, enolate-mediated palladium cross-coupling reaction, and acid-catalyzed formation of the C(7)-C(17) bond. In addition, the triethylsilane/TFA-mediated incorporation of the 2alpha-H (11 to 12) and the borohydride generation of the C(17) hydroxyl function (R) were also stereospecific. The unique highly conjested carbon skeletons of the two alkaloids were completed in a concise manner and in regiospecific fashion.
authors.affiliation: Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA.
authors.forename: Jianming
authors.initials: J
authors.lastname: Yu
authors.forename: Xiangyu Z
authors.initials: XZ
authors.lastname: Wearing
authors.forename: James M
authors.initials: JM
authors.lastname: Cook
mesh_terms: D031051:Alstonia / Q000737:chemistry; D026121:Indole Alkaloids / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: C485202:11-methoxy-17-epivincamajine; D026121:Indole Alkaloids; C485203:vincamajinine