An efficient primary-amine-directed, palladiumcatalyzed CÀ H halogenation (X = I, Br, Cl) of phenylalanine derivatives is reported on a range of quaternary amino acid (AA) derivatives thanks to suitable conditions employing trifluoroacetic acid as additive. The extension of this original native functionality-directed ortho-selective halogenation was even demonstrated with the more challenging native phenylalanine as tertiary AA.

The link is shown between a pioneering chemist's questioning – drawing and sharing thoughts on a blackboard – and a solution by means of modern catalytic tools – illustrated by computer lettering. Our question was how to regioselectively introduce a halogen atom into valuable phenylalanine derivatives without using a heavy protecting group in order to rapidly construct nonproteinogenic amino acids. The proposed solution was a Pd‐catalyzed and sustainable regioselective C−H halogenation process directed by a native amine functional group. More information can be found in the Communication by G. Journot, C. Schneider, J.‐F. Brière et al. (DOI: 10.1002/chem.202102411).