Coumarin 343, C₁₆H₁₅NO₄

In the title compound, 2,3,6,7-tetrahydro-11-oxo-1H,5H,11H-[1]benzopyrano [6,7,8-ij]quinolizine-10-carboxylic acid, the coumarin moiety is planar. The two piperidine rings take flattened sofa conformations. There is an intramolecular hydrogen bond between the carbonyl group and the carboxyl group, and the hydrogen bond influences the bond lengths in the pyron ring. The crystal packing is governed by van der Waals forces.

-1