2-(1,3-Dithian-2-ylidene)-1-phenylbutane-1,3-dione

The title compound, C13H12O2S2, belonging to the group of dioxoketene cyclic S,S-acetals, was prepared from the corresponding dione in high yield. In the structure, the C=O and C=C bonds are not coplanar, with O=C—C=C torsion angles of 36.8 (4) and 21.0 (4)°. The dithian ring has a twisted conformation.