Diastereoselective synthesis of enantiopure differentially protected cis-4,5-diaminopiperidin-2-one through intramolecular transamidation

The diastereoselective synthesis of enantiopure differentially protected cis-4,5-diaminopiperidin-2-one was achieved by means of conjugate addition of ammonia to an unsaturated γ-lactam and transamidation reaction with ring expansion as the main steps.