[35742-60-0] · C8H8O2Pd · Phenylpalladium Acetate · (MW 228.58)
(used for the phenylation of alkenes)
Solubility: sol acetonitrile, methanol, acetic acid, THF, benzene, chloroform, monoglyme, and diglyme.
Preparative Methods: (1) from PhN(NO)COMe (1 mmol) and Bis(dibenzylideneacetone)palladium(0) (0.2 mmol) in acetonitrile at 40 °C for 2 h;2 (2) from SbPh3 or Triphenylphosphine (0.5 mmol) and Palladium(II) Acetate (0.5 mmol) under the same conditions;2 (3) from PhHg(OAc) (10 mmol) and Pd(OAc)2 (10 mmol) in 1:1 acetone-water (200 mL) at 30 °C for 2 h.3
Handling, Storage, and Precautions: very reactive and unstable, and is therefore formed in situ. Decomposition gives palladium metal which should be retained for recycling.
The reagent is used for the stereospecific phenylation of alkenes. Only the trans product is formed. In contrast to traditional methods, the solvent exhibits only a small terminal vs. internal directing effect. The tendency of electron-withdrawing groups on the double bond to favor terminal substitution is reduced. In reaction with methylstyrene, PhPdCl and PhPdBr give some hydroxyphenylated products, whereas PhPd(OAc) gives only phenylated products.3 The stereo- and regiochemistry have also been studied with propene and other alkenes.4
Recently, the reaction of alkenylsilanes has been studied (eqs 1 and 2).2 The reaction was stereospecific with inversion of the relative disposition of alkene substituents. In contrast, [PhPd]BF4 gave nonspecific aryldesilylation products.
Ann K. Keep
Johnson Matthey, Royston, UK