Coumarin 338

In the title compound, 1,1-dimethylethyl 2,3,6,7-tetrahydro-11-oxo-1H,5H,11H- [1]benzopyrano[6,7,8-ij]quinolizine-10-carboxylate, C₂₀H₂₃NO₄, the coumarin moiety is approximately planar. The two piperidine rings have sofa conformations and one is disordered. The N atom adopts a planar configuration and the carboxyl group is out of the coumarin plane.