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

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.