Imposing Cross-Coupling Selectivity in Aerobic Oxidative Coupling of Phenols by [Co(salen)] Catalyst

A mechanistically driven catalyst design approach was adopted to address chemoselectivity issues in oxidative coupling of phenols. This approach guided the development of an aerobic catalytic system with unique cross-coupling selectivity which is based on Co[salen] complexes. The waste-free conditions offer a sustainable entry to non-symmetric biphenols via a novel mechanistic scheme. The reaction is carried-out under air at room temperature in a recyclable 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solvent. In HFIP, Co[salen] complexes exhibit high catalase-like activity mediating rapid disproportionation of H₂O₂ into H₂O and O₂.