Versatile Ru‐Photoredox‐Catalyzed Functionalization of Dehydro‐Amino Acids and Peptides

Abstract A versatile photoredox‐catalyzed synthesis of unnatural amino acids and peptides is presented. Commercially available Ru(bpy) 3 (PF 6 ) 2 was efficiently used as visible light photocatalyst in combination with a broad number of different types of radical precursors in the coupling with several dehydrogenated amino acid residues. This method provides new entries to the mild, selective and direct modification of both simple and complex peptide‐like compounds towards novel structures with improved or unusual properties. Hence, (fluorinated)alkyl halides, arylsulfonyl chlorides or various N ‐(acyloxy)phthalimides (NHPI esters) were effectively reacted with a series of natural and unnatural α,β‐dehydroamino acids and dipeptides. Moreover, the applicability of the process was also proved by the late stage functionalization of the naturally occurring peptide thiostrepton.