Mechanistic Studies of the Oxidative Dehydrogenation of Methanol Using a Cationic Palladium Complex

The catalytic oxidation of methanol in the presence of the cationic [neocuproinePd(OAc)] 2 [OTf] 2 (OTf = trifluoromethylsulfonate), 1, yields methyl formate. With benzoquinone as a terminal oxidant 4-hydroxyphenyl formate is also formed competitively. Mechanistic and labeling studies implicate formaldehyde and methyl hemiformal as key intermediates. Beta-hydrogen elimination from Pd-OCH 3 or Pd-OCH 2 OCH 3 intermediates is proposed as a key step in the generation of formaldehyde and methyl formate, respectively.