A practical three-step protocol for the assembly of triazolobenzodiazepine-fused diketopiperazines and hydantoins has been developed. The synthesis of these tetracyclic ring systems was initiated by an Ugi reaction, which brought together all necessary functionalities for further transformations. The Ugi adducts were then subjected to a base-induced ring closing and an intramolecular azide-alkyne cycloaddition reaction in succession to obtain highly fused benzodiazepine frameworks.
Keywords: 2,5-diketopiperazine; Ugi reaction; benzodiazepine; hydantoin; intramolecular azide–alkyne cycloaddition.