Iron-Catalyzed Diastereoselective Synthesis of Unnatural Chiral Amino Acid Derivatives

An iron-catalyzed diastereoselective synthesis of unnatural chiral (S)-alpha-amino acids with gamma-quaternary carbon centers has been developed. The protocol uses inexpensive iron salt as the catalyst, readily available 2-phthaloyl acrylamide and alkenes as the starting materials, and phenylsilane as the reductant, and the reactions were performed well in mixed solvent of 1,2-dichloroethane and ethylene glycol at room temperature. The method shows some advantages including simple and wide substrates, mild conditions, high diastereoselectivity, and easy workup procedures.