Bis(tricyclohexylphosphine)nickel(II) Dichloride

Typical procedure (Ar = Ph, R = 4-CH₃Ph): Trimethylphenylammonium iodide (132 mg), bis(tricyclohexylphosphine)nickel(II) dichloride (6.9 mg) and NMP (1.5 mL) are added to a Schlenk tube. To the stirring mixture, 4-CH₃C₆H₄ZnCl solution (1.5 mL, 1.5M solution in THF) is added by a syringe. The reaction mixture is stirred at 90 °C for 8 h and then cooled to room temperature. Water (10 mL) and several drops of acetic acid are successively added. The resulting mixture is extracted with diethyl ether (3 x 10 mL) and the extract is dried over Na₂SO₄, filtered and concentrated. The residue is purified by column chromatography on silica gel (eluent: petroleum ether or petroleum ether/ethyl acetate 60:1) to give 4-methylbiphenyl (76.5 mg, 91 %).