Electron Acceptors Based on Cyclopentannulated Anthanthrenes.

We demonstrate the preparation of anthanthrene derivatives with fused five-membered rings. These new derivatives are prepared by a palladium catalyzed cyclopentannulation reaction from precursors derived from the low-cost dye Vat Orange 3 (4,10-dibromoanthanthrone). The new cyclopentaanthanthrene compounds possess reduced optical and electrochemical gaps (∼0.9 eV) compared to anthanthrene derivatives and are electron acceptors with lowest unoccupied molecular orbital energies from ∼ -3.4 to -3.9 eV.