Functionalized arylzinc compounds in ethereal solvent: Direct synthesis from aryl iodides and zinc powder and application to Pd-catalyzed reaction with allylic halides

Arylzinc compounds, ArZnX, were conveniently prepared in high yields by the reaction of zinc powder with aryl iodides, which contain electron-withdrawing groups such as CO₂CH₃, CN, Br, or CF₃ at the ortho-, meta- or para-position, or electron-donating groups such as CH₃, OCH₃, or H, at 70 °C in THF, at 100 °C, or at 130 °C in diglyme, respectively. Pd(dba)2 exhibited an outstanding efficient catalytic effect for the cross-coupling of these ethereal solutions of ArZnX with allylic halides to afford a variety of functionalized allylbenzenes in high yields; the reactions were mostly carried out at 0 °C for 5-30 min in the presence of 5 mol % of catalyst. The conversion of the aryl iodides to allylbenzenes via two reactions could be accomplished in one pot.