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 degreesC in THF, at 100 degreesC, or at 130 degreesC 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 degreesC 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.