15-Hydroxy-ethyl-19-isopropyl-5,9-dimethyl-14,16-dioxo-15-aza-penta-cyclo-[10.5.2.0.0.0]nona-dec-18-ene-5-carboxylic acid.

The title compound, C(26)H(37)NO(5), which was synthesized from monoethano-lamine and maleopimaric acid, consists of two fused and unbridged cyclo-hexane rings. They form a trans ring junction with a chair conformation. The two methyl groups are in axial positions. In the crystal, inter-molecular O-H⋯O hydrogen bonds link adjacent mol-ecules into a layer structure. Two C-H⋯O interactions are also present.