Direct, visible light-sensitized benzylic C[sbnd]H fluorination of peptides using dibenzosuberenone: selectivity for phenylalanine-like residues

Abstract

A visible light-sensitized benzylic sp3 CH fluorination protocol using dibenzosuberenone (5 mol %) and Selectfluor® is optimized for the direct functionalization of phenylalanine-like residues in short chain peptides. Amino acids, dipeptides, and tripeptides undergo benzylic fluorination with remarkable regioselectivity in the presence of protected basic, acidic, and nonpolar side chains (including those with tertiary sites). Additionally, protecting group compatibility, a gram scale application, and competition experiments were explored.