Photocatalytic Phosphine‐Mediated Deoxygenative Coupling of Aspartic/Glutamic Acid Residues and Azobenzenes to Access Hydrazide‐Containing Unnatural Amino Acids

Herein, we have developed a novel synergistic catalysis strategy combining visible‐light photocatalysis with triphenylphosphine, enabling efficient and highly selective deoxygenative coupling of aspartic/glutamic acid derivatives with azobenzene. This approach provides a general and versatile method for synthesizing a series of pharmacologically interesting hydrazide‐containing unnatural amino acids. Mechanistic studies confirmed a radical‐based pathway and elucidated the unique role of DMAP in modulating the reaction pathway through stabilization of the critical intermediate. This approach provides a new type of amino acids residues with robust active site, which are significant organic building blocks and potential bioactivity.