Efficient Cobalt-Catalyzed Methylation of Amines Using Methanol

The methylation of amines using methanol is a promising route to synthesize N-methylamines, and the development of cheap and efficient catalytic system for this reaction is of great significance. Herein, we reported a cobalt (Co)-based catalytic system, which was in situ formed from commercially available Co precursor and a tetradentate phosphine ligand P(CH2CH2PPh2)3 combined with K3PO4. This catalystic system was very effective for the selective production of dimethylated products from aliphatic amines and monomethylated ones from aromatic amines. The reaction mechanism was further investigated by control and isotope labelling experiments.