9a-Propargyl-1,2,3,9-tetrahydrofluorene-3,9-dione

In the title compound, C16H12O2, the six-membered ring adopts a half-chair conformation and the fused five-membered ring is in a conformation between flattened sofa and half-chair. The propargyl residue is twisted diagonally towards the five-membered ring. In the solid state, the propargyl group is involved in C-H ... O intermolecular hydrogen bonds to form an infinite one -dimensional chain along the a axis.