Iron-Catalyzed Oppenauer-Type Oxidation of Alcohols

A (hydroxycyclopentadienyl)iron dicarbonyl hydride catalyzes the Oppenauer-type oxidation of alcohols with acetone as the hydrogen acceptor. Many functional groups are tolerant to the oxidation conditions. The same complex also catalyzes the dehydrogenation of diols to lactones. A mechanism involving the formation of iron-alcohol complexes and their rapid ligand exchange with free alcohols is proposed. The trimethylsilyl groups on the cyclopentadienyl ligand of the catalyst play a critical role in stabilizing the iron hydride and increasing the catalyst lifetime.