A Unique and Efficient Ni Catalyst for Cross-Coupling Reactions

The Ni-based catalyst bis(tricyclohexylphosphine)nickel(II) dichloride [NiCl₂(PCy₃)₂] (1) has been reported as a unique and efficient transition metal catalyst for cross-coupling reactions (e.g. Suzuki–Miyaura, Kumada, etc.), which are efficient methods for the construction of C–C bonds.

Typical Procedure^1a):
A dried flask is filled with argon and charged with K₃PO₄ (212 mg), 2-naphthyl p-toluenesulfonate (149 mg), phenylboronic acid (91.5 mg), PCy₃ (16.8 mg) and 1 (10.3 mg). The flask is evacuated, back-filled with argon and then dioxane (5 mL) is added. The reaction mixture is stirred at 130 °C until the starting toluenesulfonate have been consumed or after 60 h. The solution is then allowed to cool to room temperature, taken up in ether (20 mL) and washed with aqueous NaOH (1 M, 5 mL) and brine (2 x 5 mL). The organic layer is dried over MgSO₄, filtered, concentrated in vacuo and then the crude product is purified by flash chromatography on silica gel to give 2-phenylnaphthalene as a white solid (100 mg, Y. 98%).