Oxidative addition in the coupling of alkylgold(I) with alkyl halides

MeAu(PPh3) reacts with MeI to afford C2H6 and I(PPh3)Au by a multi-step mechanism involving: (i) oxidative addition to form an intermediate Me2AuI(PPh3) species, which (ii), undergoes iodide-methyl exchange with another MeAu(PPh3) species to afford Me3Au(PPh3), followed by (iii), reductive elimination of C2H6 and reformation of MeAu(PPh3). The more reactive trime thylphosphine derivative also readily undergoes (i) oxidative addition and (ii) methyl exchange. However, Me3Au(PMe3) is more stable than the PPh3 analog and does not undergo (iii) reductive elimination. Instead, it is involved in (iv), a further very slow reaction with IAu(PMe3) and MeI to afford Me2 AuI(PMe3) in high yields. C2H5Au(PPh3) specifically affords n-C4H10 at 0° in MeI. Reactions of other alkylgold(I) complexes with alkyl halides are also reported, and fit into a general mechanistic pattern desribed by reactions (i) – (iv).