1-Acetyl-3-[1-(4-methoxyphenyl)-2-oxopropylidene]-1H-indol-2(3H)-one: a twinned crystal.

The crystal of the title compound, C(20)H(17)NO(4), which was used for collecting intensity data was twinned. Each of the two crystallographically independent molecules in the asymmetric unit has a planar indole moiety perpendicular to a planar oxopropyl moiety. The distribution of the bonds at the central C atom joining the oxopropyl, phenyl and indole substituents is also planar. The packing is stabilized by intermolecular C-H* * *O interactions, as well as by dipole-dipole and van der Waals interactions.