title: Synthesis of cyano-substituted diaryltetracenes from tetraaryl[3]cumulenes.
abstract: A versatile, two-step synthesis of highly substituted, cyano-functionalized diaryltetracenes has been developed, starting from easily accessible tetraaryl[3]cumulenes. This unprecedented transformation is initiated by [2+2] cycloaddition of tetracyanoethylene (TCNE) to the proacetylenic central double bond of the cumulenes to give an intermediate zwitterion, which after an electrocyclization cascade and dehydrogenation yields 5,5,11,11-tetracyano-5,11-dihydrotetracenes in a one-pot procedure. A subsequent copper-assisted decyanation/aromatization provided the target 5,11-dicyano-6,12-diaryltetracene derivatives. All of the postulated structures were confirmed by X-ray crystallography. The new chromophores are thermally highly stable and feature promising fluorescence properties for potential use in optoelectronic devices. They are selective chemosensors for Cu(I) ions, which coordinate to one of the CN substituents and form a 1:1 complex with an association constant of Ka =1.5×10(5)  L mol(-1) at 298 K.
authors.affiliation: Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich (Switzerland).
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Gawel
authors.forename: Cagatay
authors.initials: C
authors.lastname: Dengiz
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Finke
authors.forename: Nils
authors.initials: N
authors.lastname: Trapp
authors.forename: Corinne
authors.initials: C
authors.lastname: Boudon
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Gisselbrecht
authors.forename: François
authors.initials: F
authors.lastname: Diederich
keywords: [2+2] cycloaddition; [3]cumulenes; chemosensors; electrocyclization; tetracenes