Access to Electron-Rich Dibenzofurans through NBu4OAc-Mediated Palladium Catalysis

Dibenzofuran and its derivatives are ubiquitous and important medicinal and natural products. Many contain electron-rich aryl rings. Forming the key intramolecular Ar-Ar bond using traditional cross-coupling is difficult. The C-H functionalisation (C-H activation) approach is, in principle, far more useful. However, we previously found that the well-established conditions, which promote C-H functionalisation through Concerted Metalation-Deprotonation (CMD), proved unsatisfactory. Herein, we report a Pd-catalysed C-H functionalisation protocol that works with electron-rich arenes. We use tetrabutylammonium acetate (NBu4OAc), which we suspect can act as base, ligand and solvent, rendering this protocol a simple and efficient route to electron-rich dibenzofurans.