Palladium-Catalyzed Methylation of Nitroarenes with Methanol.

A procedure for the synthesis of N-methyl-arylamines directly from nitroarenes using methanol as green methylating agent was developed. The key to success is the use of a specific catalyst system consisting of palladium acetate and the ligand 1-[2,6-bis(isopropyl)phenyl]-2-[tert-butyl(2-pyridinyl)phosphino]-1H-Imidazole (L1). The generality of this protocol is demonstrated in the synthesis of more than 20 N-methyl-arylamines under comparably mild conditions. Combining this novel methodology with subsequent coupling processes using the same catalyst allows for efficient diversification of aromatic nitro compounds to a broad variety of amines including drug molecules.