THE WACKER OXIDATION

摘要

The Wacker oxidation is both an industrially viable and synthetically useful transformation to access methyl ketones from terminal alkenes that generally uses a Pd(II) catalyst and co-oxidant (Scheme 1). This reaction has a rich history dating back to the discovery of the stoichiometric conversion of ethylene into acetaldehyde mediated by an acidic, aqueous solution of PdCl2. For more than a half century, this report received little attention until chemists at the Consortium fur Elektrochemische Industrie, the research organization for Wacker Chemie, reported what is now termed the Wacker process using catalytic amounts of Pd(II) and stoichiometric amounts of Cu(II) under acidic, aqueous, aerobic conditions (Scheme 1). The motivation for the development of this process was to avoid a difficult two-step hydration-oxidation of ethylene into acetaldehyde. The mechanistic and technical details of the Wacker process are in themselves very impressive, but the focus of this chapter will be applications of this general transformation in synthetic chemistry.