Practical Oppenauer (OPP) oxidation of alcohols with a modified aluminum catalyst.

[reaction: see text] Modified aluminum catalyst 2 was found to be highly effective for Oppenauer (OPP) oxidation of alcohols under mild conditions. For example, oxidation of carveol in toluene with t-BuCHO (1.2 equiv) as a hydride acceptor in the presence of 2 (1 mol %) proceeded smoothly at 21 degrees C to give carvone in 94% yield after 1 h. A practical aspect of this system was highlighted by the facile OPP oxidation of terpenoids and steroids with 1.2-3.0 equiv of acetone and 2 (3-5 mol %).