title: Stereoselective cascade double-annulations provide diversely ring-fused tetracyclic benzopyrones.
abstract: A cascade double-annulation strategy employing diverse pairs of zwitterions with 3-formylchromones is presented that provides stereoselective access to complex tetracyclic benzopyrones. Different zwitterions incorporated different rings that include aza-, oxa-, and carbocycles fused to a common benzopyrone scaffold and in the process created three contiguous chiral centers including an all-carbon-quaternary center with high efficiency and excellent stereoselectivity.
authors.affiliation: Abteilung Chemische Biologie, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
authors.forename: Baburaj
authors.initials: B
authors.lastname: Baskar
authors.forename: Kathrin
authors.initials: K
authors.lastname: Wittstein
authors.forename: Muthukumar G
authors.initials: MG
authors.lastname: Sankar
authors.forename: Vivek
authors.initials: V
authors.lastname: Khedkar
authors.forename: Markus
authors.initials: M
authors.lastname: Schürmann
authors.forename: Kamal
authors.initials: K
authors.lastname: Kumar
mesh_terms: D003500:Cyclization; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011753:Pyrones / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; D011753:Pyrones