N‑Monomethylation of Aromatic Amines with Methanol via PNHP‑Pincer Ru Catalysts

The use of methanol for the selective methylation of aromatic amines with RuHCl­(CO)­(PNHP) (PNHP = bis­(2-diphenyl­phosphino­ethyl)­amine) is reported. Various aromatic amines were transformed into their corresponding monomethylated secondary amines in high yields at 150 °C with a very low catalyst loading (0.02–0.1 mol %) in the presence of KO t Bu (20–60 mol %). The catalyst precursor, RuHCl­(CO)­(PNHP), was converted to [RuH­(CO)2(PNHP)]+ under the catalytic conditions and also serves as a highly effective catalyst. The robustness of this catalyst contributes to its outstanding catalytic activity, even under reaction conditions, in which CO is liberated from methanol.