Ligand-Promoted γ-C(sp3)-H Arylation and Unsymmetrical Diarylation to Access Unnatural Amino Acid Derivatives.

A palladium(II)-catalyzed arylation of a γ-C(sp3)-H bond of protected amino acid is explored. The monoarylation is promoted by the commercially available, inexpensive phenanthroline ligand, and toxic silver salt is replaced by earth-abundant Mn(III)acetate. Subsequently, a hitherto unknown unsymmetrical diarylation at the γ-position is accomplished under the modified reaction conditions. Ligands have a prominent influence in both mono- and unsymmetrical diarylations.