Efficient synthesis of polyfunctionalised enantiopure diazepanone scaffolds

The synthesis of polyfunctionalised enantiopure 1,4-diazepan-3-one scaffolds from l-serine derivatives and azidoepoxides readily available from either l-ascorbic or d-isoascorbic acid, allowing access to various configurations at chiral centres, is described. The key steps are the nucleophilic opening of the epoxide by the amine of serine followed by a lactonisation–lactamisation sequence.