Ortho-C–H Benzylation of Aryl Imines with Benzyl Phosphates under Cobalt–Pyphos Catalysis

Ortho-C–H benzylation of aryl ketimines with benzyl phosphates is achieved with the aid of a catalytic system consisting of a cobalt­(II) salt, a phosphine/pyridine bidentate ligand, and a Grignard reagent under room-temperature conditions, affording a variety of diarylmethanes bearing <i>o</i>-acetyl or -acyl groups in moderate to good yields. Owing to the versatility of the <i>o</i>-acetyl group, the reaction opens useful synthetic routes to polycyclic compounds such as unsymmetrical anthracene, anthracenone, and anthraquinone derivatives