E-Benzoquinone

Transition metal complexes of e>-benzoquinone, o-semiquinone and catecholate ligands. C. G. Pier-pont and R. M. Buchanan, Coord. Chem. Rev., 1981,38,45-87 (72). 

The reaction requires a stoichiometric amount of palladium(II) salt or a reoxidant must be used to achieve a catalytic reaction (oxidative carbonylation) (Scheme 13.42). A great variety of external oxidants, either organic (i.e., benzoquinone) or inorganic (i.e., copper(II) salts), have been evaluated and described. Moreover, a particularly... 

---