A new transient directing group diethoxyethyl-L-proline facilitates ortho -arylation of aryl-amines/-amino acids via Pd-catalyzed C(sp 2 )-H activation.

Mono- ortho -arylated arylamines are constituents of various natural products but their syntheses are challenging. This report describes a new synthetic methodology for the ortho -arylation of arylamines and α-aromatic amino acids (phenylglycine and phenylalanine) through a Pd-catalyzed C(sp 2 )-H activation using the synthetic transient directing group diethoxyethyl-L-proline (DEP). A catalytic amount of diethoxyethyl-L-proline is sufficient to form mono-arylated arylamines as the major products using aryliodides. This method could be useful for the synthesis of various biphenyl amines and novel peptidomimetics.