Au(I)/Au(III) Catalytic Allylation Involving π-Allyl Au(III) Complexes

Abstract : A (MeDalphos)AuCl complex was found to efficiently catalyze the cross-coupling of indoles and allyl acetates/alcohols. The reaction tolerates many functional groups and selectively affords the branched C3-allylated products from both α- and γ-substituted allyl substrates. It takes the advantage of the hemilabile character of the P∧N ligand. The C(sp2)-C(sp3) coupling operates via a Au(I)/Au(III) redox cycle and involves a dicationic π-allyl Au(III) complex as a key intermediate. In this case, the allyl moiety adopts an asymmetric σ + π-coordination mode, as substantiated by NMR spectroscopy and density functional theory (DFT) calculations.