Reusable, Efficient Manganese–Copper-Catalyzed Cross-Coupling of Aryl Halides with Aromatic Alcohols under Solvent-Minimized Conditions

We report an efficient ligand-free manganese–copper-catalyzed cross-coupling reaction of differently substituted aryl halides (chlorides, bromides, and iodides) with various aromatic alcohols, conducted under solvent-minimized conditions. This cost-effective method efficiently produces the desired cross-coupling products (diaryl ethers) in good to excellent yields, showcasing a broad substrate scope (65 examples) and tolerance to many sensitive functional groups such as ─CN, ─CHO, ─COOH, ─COCH₃, ─CO₂Et, ─SO₂NH₂, ─NH₂, ─NO₂, ─CH═CH₂, and heterocycles. No conventional work-up is essential for this protocol, and the established method is useful for gram-scale synthesis. Importantly, the catalyst is environmentally friendly, inexpensive, and can be reused at least seven times with insignificant loss of catalytic activity. Several experiments, including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV spectroscopy, were carried out to identify the oxidation state of active catalytic species. Additionally, a radical clock experiment using a radical probe was performed to investigate the reaction mechanism.