Maleopimaric anhydride ethyl ester

The title compound, C₂₆H₃₆O₅, is a derivative of abietic acid formed by an endo-Diels-Alder reaction between maleic anhydride and the diene levopimaric acid ethyl ester. The two fused and unbridged cyclohexane rings have chair conformations and the anhydride ring is planar.