Crystal structure of ethyl 2-methyl-5,10-dioxo-4-phenyl-5,10-dihydro-4H-11-thia-1,4a-diaza-benzo[b]fluorene-3-carboxylate

The title compound, C₂₄H₁₈N₂O₄S, crystallizes in the orthorhombic P2₁2₁2₁ space group, indicating the existence of only one enantiomer with an S configuration of the chiral center in the crystal phase. The dihydropyrimidine ring adopts a twist-boat conformation while the quinone ring is slightly non-planar. In the crystal, molecules are linked by weak C-H O and C-H S hydrogen bonds and C-H interactions. In addition, a short intermolecular S N contact of 3.250 (3) Å indicates an interaction between the S atom and the -system of the thiazole ring.