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Synthesis of Cyano-Substituted Diaryltetracenes from Tetraaryl[3] cumulenes**

GAWEL, Przemyslaw
Dengiz, Çağatay
FINKE, Aaron D.
BOUDON, Corinne
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 K-a=1.5x10(5)Lmol(-1) at 298K.