Ir-Catalyzed Cycloaddition of Tribenzocyclyne with Biphenylenes

We demonstrate that Ir-catalyzed C–C bond activation in biphenylenes followed by a reaction with tribenzocyclyne is a suitable method for synthesizing strained and unknown monoadducts with the tetradehydrotetrabenzo­[a,c,e,i]­cyclododecene scaffold ([12]­annulenes). Modification of reaction conditions also furnished [12]­annulene products with cis and/or trans double bonds formed by hydrogen transfer. The [9]­annulene side product was formed upon the reaction of the benzyl radical with tribenzocyclyne during the Bergman cyclization. All isolated compounds were fully characterized by HRMS, NMR, and X-ray diffraction analysis.