Regioselective Postsynthetic Modification of Phenylalanine Side Chains of Peptides Leading to Uncommon ortho‐Iodinated Analogues

A convenient and direct iodination of Phe residues in peptide sequences was observed upon treatment with IPy2BF4. The experimental conditions were optimized (see scheme) and the role of the peptidyl fragment to drive the formation of the elusive ortho-iodo isomer as the major product was investigated.