Sustainable Mn‐Assisted Cu‐Catalyzed Cross‐Coupling of Primary Amides and Sulfonamides with (Hetero)Aryl and Styryl Halides: Investigating a Novel Catalytically Active Species

We report, for the first time, an efficient manganese (Mn)-assisted copper (Cu)-catalyzed cross-coupling reaction that involves a range of aryl, heteroaryl, and styrenyl halides with various primary amides, sulfonamides, and cinnamamide, in air without solvents or added ligands. This cost-effective protocol successfully produced the desired cross-coupling products-N-aryl and N-styryl amides, sulfonamides, and cinnamamides-in good to excellent yields. It demonstrates a broad substrate scope (98 examples) and is tolerant to various sensitive functionalities such as -COCH3, -CO2Et, -NO2, -OH, -NH2, -Br, -Cl, -F, -CF3, -OCF3, -OCH3, -CH2Ph, and heterocycles. No conventional workup is needed for this protocol, and the developed method is suitable for gram-scale synthesis. Notably, the catalyst is cost-effective, environmentally benign, and can be reused at least five times with minimal loss of catalytic activity. This protocol demonstrates a lower E-factor and PMI value compared to other methods, indicating its sustainability and benignity. Several experiments, including X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM), were carried out to identify the catalytically active species based on Mn-Cu and their oxidation state. Additionally, a radical clock experiment was performed using a radical probe to investigate the reaction mechanism, and a novel Mn-Cu-based catalytic cycle for this transformation has been proposed.