5,5-Diethyl-1-methyl-1H,2H,3H,5H-pyrimidine-2-spiro-9'-fluorene-4,6-dione

The title compound, C₂₁H₂₂N₂O₂, was synthesized from the corresponding pyrazolidinedione precursor by 9-fluorenyl substitution and subsequent ring expansion. The hexahydropyrimidinedione (HHPD) ring has a very flattened chair conformation and is nearly perpendicular [88.79 (13)°] to the 2-spiro-9′-fluorene ring. The two ethyl groups adopt a folded conformation and lie on opposite sides of the HHPD ring. A hydrogen-bonding scheme consisting of N—H...O=C and C—H...O=C interactions produces parallel molecular layers.

-1