title: Total synthesis of (+)-seco-C-oleanane via stepwise controlled radical cascade cyclization.
abstract: An asymmetric concise total synthesis of the (+)-seco-C-oleanane 1 was accomplished. The successful route to this natural product involves as the key step a stepwise regio- and stereocontrolled catalytic radical polyene cascade cyclization from preoleanatetraene oxide (16), a process mediated by Cp(2)TiCl. The use of this single-electron-transfer complex permits mild cyclization conditions without using unnecessary prefunctionalizations and stops the process at the bicyclic level. Theoretical data revealed high activation energy for the third ring closure, which would account for the control of the cyclization. This process also led to natural (-)-achilleol B, camelliol A, and (+)-seco-β-amyrin as minor compounds.
authors.affiliation: Department of Organic Chemistry, Institute of Biotechnology, University of Granada, Avda. Fuentenueva, 18071 Granada, Spain.
authors.forename: Victoriano
authors.initials: V
authors.lastname: Domingo
authors.forename: Jesús F
authors.initials: JF
authors.lastname: Arteaga
authors.forename: José Luis
authors.initials: JL
authors.lastname: López Pérez
authors.forename: Rafael
authors.initials: R
authors.lastname: Peláez
authors.forename: José F
authors.initials: JF
authors.lastname: Quílez del Moral
authors.forename: Alejandro F
authors.initials: AF
authors.lastname: Barrero
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001688:Biological Products; D014315:Triterpenes; C530507:achilleol B; C413246:oleanane; D009828:Oleanolic Acid; C036380:beta-amyrin