Pd(II)/Norbornene-Catalyzed Meta-C-H Alkylation of Nosyl-Protected Phenylalanines.

A Pd/norbornene-catalyzed direct meta-alkylation of nosyl-protected phenylalanine derivatives with alkyl iodides is reported in moderate to good yields. The use of diisopropyl bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate is identified as a more suitable transient mediator. A simple pyridine ligand is also essential for this reaction to proceed. No racemization was observed in this meta-methylation reaction.