System quinone-copper acetate

The electrochemical Wacker-type oxidation of terminal olefins (111) by using palladium chloride or palladium acetate in the presence of a suitable oxidant leading to 2-alkanones (112) has been intensively studied. As recyclable double-mediatory systems (Scheme 43), quinone, ferric chloride, copper acetate, and triphenylamine have been used as co-oxidizing agents for regeneration of the Pd(II) catalyst [151]. The palladium-catalyzed anodic oxidation of... 

Oxidation of isoeugenol with (BPA)Cu(II)Clzin ethanol gave the ortho-ortho coupling dimer and the aldehyde derivatives, On the other hands, oxidation of isoeugenol in acetic acid Hz O gave the adduct of two molar isoeugenol and one molar acetic acid. When 2,6-dibutyl-4-methylphenol was oxidized in the system of copper(II) acetate-pyridine quinone methide derivatives were produced. 

Earlier studies have also shown that a catalyst system consisting of palladium(II) and copper salts plus oxygen for the reoxidation did not work well,t in contrast to the result with the Wacker oxidation. However, if quinone or hydroquinone was added to a mixture of palladium acetate and copper acetate, oxygen could be used as an efficient oxidant for conversion of alkenes into allylic acetates. Thus, cyclohexene gave better than 85% cyclohexenyl acetate (Scheme 10). The combination of oxygen and cobalt or manganese acetate also works, but less well.t ... 

A more efficient system was obtained if copper acetate was replaced by salen-type cobalt complexes as catalysts, operating together with hydroquinone or quinone. Finally, incorporation of a hydroqninone as part of the salen ligand gave an even more efficient catalyst that did not reqnire cocatalysis by quinone (Scheme 11). 

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