title: Total syntheses of codonopsinine and 4-epi-codonopsinine via gold-mediated tandem-catalyzed pyrrole synthesis.
abstract: The total syntheses of codonopsinine (1) and 4-epi-codonopsinine (2) were accomplished. The key substituted pyrrole intermediate was constructed via gold-catalyzed addition-cyclization cascade of an aminoacetaldehyde acetal derivative and a terminal alkyne. After diastereoselective reduction of the pyrrole intermediate to the corresponding 3-pyrroline derivative with zinc dust and sulfonic acid, the total synthesis of 4-epi-codonopsinine (2) was achieved via stereoselective construction of the diol by dihydroxylation. In addition, the total synthesis of codonopsinine (1) was completed through stereochemical inversion of the hydroxyl group via epoxide and subsequent ring cleavage under the acidic aqueous condition.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Minami
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Itagaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ueda
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Tokuyama
mesh_terms: D002384:Catalysis; D060326:Chemistry Techniques, Synthetic; D003500:Cyclization; D004852:Epoxy Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry*; D011759:Pyrrolidines / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013451:Sulfonic Acids / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D011758:Pyrroles; D011759:Pyrrolidines; D013451:Sulfonic Acids; C415669:codonopsinine; D017665:Hydroxyl Radical; D006046:Gold; D015032:Zinc