In an N2 filled glovebox, P( t Bu)3 (166 mg, 0.824 mmol) and mesitylcopper(I) (150 mg, 0.824 mmol) were dissolved in 2-3 mL of cold THF (-30 °C). Neat Ph2PH (153 mg, 143 μl, 0.824 mmol) was added dropwise. The resulting yellow solution was stirred for 24 h. (Note: subsequent trials with less concentrated solutions monitored by 31 P NMR indicate that full conversion is reached after 4 h). The solution was then layered with ~8 mL of pentane and placed in a freezer at -30 °C. After decanting the mother liquor, 107 mg (37 % yield) of 2 was recovered upon washing the precipitate with cold pentane and drying.