title: Synthesis of fluoranthenes and indenocorannulenes: elucidation of chiral stereoisomers on the basis of static molecular bowls.
abstract: Cycloaromatization of a peri diyne with an external alkyne provides a general route to indeno-fused polynuclear aromatics. Fluoranthenes 9 (or 13) are easily accessible in good to excellent yields (75-99%; 18 examples) from the reaction of symmetric (or asymmetric) diynes 4 and alkynes 5 (or norbornadiene) in the presence of Wilkinson's catalyst. This formal [(2+2)+2] cycloaddition can also be applied to generate various indenocorannulenes 28 from 2,3-diethynylcorannulene derivatives 27 and alkynes 5. The indenocorannulenes 28 exist in a static bowl form at room temperature with bowl-to-bowl inversion barriers higher than 24 kcal/mol. This barrier renders the rate of inversion slow enough at room temperature to establish a class of chiral, bowl-shaped stereoiomers containing no tetrahedrally ligated atoms. The crystal structure of 28g provides insight into the bowl-shaped geometry of these compounds. This new synthetic method occurs under neutral conditions and tolerates various functional groups (e.g., alkyl, aryl, alcohols, and esters).
authors.affiliation: Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Yao-Ting
authors.initials: YT
authors.lastname: Wu
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Hayama
authors.forename: Kim K
authors.initials: KK
authors.lastname: Baldridge
authors.forename: Anthony
authors.initials: A
authors.lastname: Linden
authors.forename: Jay S
authors.initials: JS
authors.lastname: Siegel