A New Approach to the Synthesis of γ-Keto-α-Amino Acids: Synthesis of Optically Pure 5-Hydroxy-4-oxo-L-norvaline, L-HON

The nucleophilic ring opening of activated monocyclic (β-lactams by trimethylsulphoxonium ylide, lithiated sulphones and cuprates is reported. Conversion of the resultant ring opened forms to a variety of funtionalised γ-keto-α-amino acids is described as exemplified by a short synthesis of the natural product 5-hydroxy-4- oxo-L????-noivaline, L????-HON.