Sequential Ugi reaction/base-induced ring closing/IAAC protocol toward triazolobenzodiazepine-fused diketopiperazines and hydantoins.

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.

8-Methyl-3-methyl-sulfanyl-8a,8b-di-hydro-5H-1-oxa-2,4-di-aza-ace-naphthyl-ene.

In the tricyclic title compound, C11H12N2OS, the 2,3,4,5-tetra-hydro-pyridine ring adopts a half-chair conformation. This ring makes dihedral angles of 27.72 (7) and 45.17 (7)°, respectively, with the isoxazole and the cyclo-hexa-1,3-diene rings while the isoxazole ring is oriented at an acute angle of 63.46 (7)° with respect to the cyclo-hexa-1,3-diene ring. In the crystal, mol-ecules associate via C-H⋯N hydrogen bonds and C-H⋯π inter-actions, forming a three-dimensional network.