Iron-Catalyzed C(sp2)-C(sp3) Cross-Coupling of Alkyl Grignard Reagents with Polyaromatic Tosylates

The iron-catalyzed cross-coupling of polyaromatic tosylates with alkyl Grignard reagents controlled by O-coordinating ligand is reported. The reaction operates under very mild, operationally practical conditions to furnish alkylated polyaromatics that are a common motif in a wide range of electronic-material, pharmaceutical and high-performance fluid applications. The challenging C(sp(2))-C(sp(3)) cross-coupling products are obtained in good to excellent yields obviating the problems associated with beta-hydride elimination. For the first time the coupling of polyaromatic tosylates can be achieved in the presence of sensitive carboxylic acid derived functional groups. Mechanistic studies suggest that the reaction selectivity can be correlated with the reduction potential of polyaromatic hydrocarbons. The method represents a rare example of sustainable C-O bond alkylation of polyarenes at room temperature.