title: Enantioselective Total Synthesis of Secalonic Acid E.
abstract: The first enantioselective synthesis of a secalonic acid containing a dimeric tetrahydroxanthenone skeleton is described, using a Wacker-type cyclization of a methoxyphenolic compound to form a chiral chroman with a quaternary carbon stereogenic center with >99% ee. Further steps are a Sharpless dihydroxylation and a Dieckmann condensation to give a tetrahydroxanthenone. A late-stage one-pot palladium-catalyzed Suzuki-dimerization reaction leads to the 2,2'-biphenol linkage to complete the enantioselective total synthesis of secalonic acid E in 18 steps with 8% overall yield.
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany).
authors.forename: Dhandapani
authors.initials: D
authors.lastname: Ganapathy
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany).
authors.forename: Johannes R
authors.initials: JR
authors.lastname: Reiner
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany).
authors.forename: Lorenz E
authors.initials: LE
authors.lastname: Löffler
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany).
authors.forename: Ling
authors.initials: L
authors.lastname: Ma
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany).
authors.forename: Boopathy
authors.initials: B
authors.lastname: Gnanaprakasam
authors.affiliation: Institute of Inorganic Chemistry, Georg-August University of Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany).
authors.forename: Benedikt
authors.initials: B
authors.lastname: Niepötter
authors.affiliation: Institute of Inorganic Chemistry, Georg-August University of Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany).
authors.forename: Ingo
authors.initials: I
authors.lastname: Koehne
authors.affiliation: Institute of Organic and Biomolecular Chemistry, Georg-August University of Göttingen, Tammannstrasse 2, 37077 Göttingen (Germany). ltietze@gwdg.de.
authors.forename: Lutz F
authors.initials: LF
authors.lastname: Tietze
keywords: Wacker oxidation; enantioselective reactions; palladium; secalonic acids; total synthesis; xanthone