3,5-Bis(4-chloro-benzyl-idene)-1-methyl-piperidin-4-one.

In the title mol-ecule, C(20)H(17)Cl(2)NO, the central heterocyclic ring adopts a flattened boat conformation. The dihedral angles between the planar part of this central heterocyclic ring [maximum deviation = 0.004 (1) Å] and the two almost planar side-chain fragments [maximum deviations = 0.015 (1) and 0.019 (1) Å], that include the aromatic ring and bridging atoms, are 18.1 (1) and 18.0 (1)°. In the crystal, pairs of weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into inversion dimers that form stacks along the a axis. The structure is further stabilized by weak inter-molecular C-H⋯π inter-actions involving the benzene rings.