7,7-Dimethyl-5 H-di­benzo[ e, i][1,4,8]triaza­cyclo­undecine-6,9,15(7 H,8 H,14 H)-trione pyridine solvate.

The X-ray crystal structure and hydrogen-bonding patterns of the title compound, C18H17N3O3·C5H5N, a non- N-alkyl­ated cyclotripeptide containing one α- and two β-amino acids, are reported. The amides in the 11-membered ring have an unprecedented all- transoid configuration. The torsion angles and Dunitz parameters describing non-planarity of the amides contained in the cyclotripeptide are discussed. [ABSTRACT FROM AUTHOR]