Key indicators: single-crystal X-ray study; T = 273 K; mean (C-C) = 0.008 Å; R factor = 0.040; wR factor = 0.115; data-to-parameter ratio = 10.5. RefinementR[F 2 > 2(F 2 )] = 0.040 wR(F 2 ) = 0.115 S = 1.02 4081 reflections 272 parameters H-atom parameters constrained Á max = 0.31 e Å À3 Á min = À0.20 e Å À3

In the title compound, C17H15Cl2NO, the dimethyl­amino­phenyl group is close to coplanar with the central propenone group [dihedral angle = 13.1 (1)° between the mean planes], while the dichloro­phenyl group is twisted from the plane [dihedral angle = 64.0 (1)°]. In the crystal, C—H⋯O and weak C—H⋯π inter­actions are formed between mol­ecules.

Key indicators: single-crystal X-ray study; T = 273 K; mean (C-C) = 0.003 Å; R factor = 0.069; wR factor = 0.182; data-to-parameter ratio = 18.5.In the title compound, C 26 H 30 O 5 , both the double bonds exist in an E configuration. The aryl rings are not coplanar with the adjacent olefinic groups owing to non-bonded interactions between the ortho H atoms of the aryl rings and the equatorial H atoms at the 3-and 5-positions of the cyclohexyl ring; the dihedral angles between the aryl rings and the olefinic groups are 33.7 (3) and 48.6 (4) . The cyclohexanone ring adopts an envelope conformation and the crystal structure is stabilized by C-HÁ Á ÁO hydrogen bonds. Experimental Crystal data C 26 H 30 O 5 M r = 422.5 Monoclinic, P2 1 =n a = 10.3766 (10) Å b = 8.6973 (9) Å c = 24.555 (3) Å = 93.500 (2) V = 2212.0 (4) Å 3 Z = 4 Mo K radiation = 0.09 mm À1 T = 273 (2) K 0.25 Â 0.21 Â 0.20 mm Data collection Bruker SMART CCD area-detector diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 1997) T min = 0.983, T max = 0.986 18534 measured reflections 5285 independent reflections 3034 reflections with I > 2(I) R int = 0.055