Allylation of Aryl Halides: Generation and Use of σ-Allylpalladium

Significance

The authors have developed a new method for the allylation reaction of aryl halides. The use of allylic alcohols under palladium catalysis is proposed to proceed through a retro-allylation reaction to generate a σ-allylpalladium species that reductively eliminates to form the aryl-allyl C-C bond. Aryl groups containing electron-donating and electron-withdrawing groups give similar yields. Aryl iodides, bromides and triflates are reactive, whereas the chlorine analogues are considerable less reactive. The use of diastereomerically pure allylic alcohol starting materials allows for either E or Z isomer enrichment dependent on the relative configuration of the substrate.