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.

研究发现，(MeDalphos)配位的氯化金(I)配合物可高效催化吲哚与烯丙基酯/烯丙醇的交叉偶联反应。该反应具备优异的官能团耐受性，可从α-取代与γ-取代的烯丙基底物中选择性生成支链型C3位烯丙基化产物。本催化体系借助了P∧N双齿配体的半不稳定特性，C(sp²)-C(sp³)碳碳偶联经由Au(I)/Au(III)氧化还原循环完成，其关键中间体为双阳离子型π-烯丙基金(III)配合物。在此过程中，烯丙基片段采取不对称σ+π配位模式，该结论已通过核磁共振波谱法与密度泛函理论（DFT）计算得以验证。