All manipulations were performed under a nitrogen atmosphere with dry, oxygenfree solvents using an M. Braun glovebox or standard Schlenk techniques. Tetrahydrofuran was dried over sodium/benzophenone and vacuum transferred. Benzene-d6 was purchased and then degassed and dried over 3 and 4 Å molecular sieves. Diphenylphosphine , copper(I)chloride , and mesitylcopper(I) , were synthesized according to literature procedures and stored under an inert atmosphere of N2. Potassium diphenylphosphine was made by a modified literature procedure in which Ph2PH was deprotonated by KH in THF and then filtered through celite, and concentrated to dryness by vacuum. All other reagents were acquired from commercial sources and dried by conventional means, as necessary. 1 H, 13 C, 31 P and 31 P HMBC NMR spectra were recorded with a Bruker AXR 500 MHz spectrometer. All 1-D 31 P NMR spectra were 1 H decoupled. Resonances in 1 H NMR spectra are referenced to the residual solvent resonance (C6D6 = δ 7.16).