title: Total syntheses of (+)-alopecuridine, (+)-sieboldine A, and (-)-lycojapodine A.
abstract: (+)-Alopecuridine, (+)-sieboldine A, and (-)-lycojapodine A, three structurally unique and related lycopodium alkaloids, have been synthesized in enantiomeric forms through an efficient strategy. The main synthetic approach for (+)-alopecuridine features a semipinacol rearrangement of hydroxyl epoxide to construct the spiro 6,9-azacarbocycles with an all-carbon quaternary center and a late-stage SmI(2)-mediated intramolecular coupling to form the 5-membered ring. Subsequently, the biomimetic synthesis of (+)-sieboldine A and (-)-lycojapodine A was accomplished successfully through two different bioinspired oxidations after a wide search for the oxidation methods. As a result, (+)-sieboldine A was derived from (+)-alopecuridine through an N-oxidation/nitrone formation process and (-)-lycojapodine A through an interesting cyclic hemiketal formation/oxidative diol cleavage pathway. These results confirmed the biogenetic relationship among the three alkaloids.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, PR China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Shao
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: Tu
authors.forename: Fu-Min
authors.initials: FM
authors.lastname: Zhang
authors.forename: Shao-Hua
authors.initials: SH
authors.lastname: Wang
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D004852:Epoxy Compounds; D006576:Heterocyclic Compounds, 4 or More Rings; D009589:Nitrogen Oxides; D013141:Spiro Compounds; C559183:alopecuridine; C539671:lycojapodine A; C015388:nitrones; C484983:sieboldine A