(E)-4-[(1-Benzyl-4-benzylidene-2,5-dioxopyrrolidin-3-yl)methyl]benzaldehyde 0.25-hydrate

The crystal structure of the title compound, C26H21NO3·0.25H2O, reveals one stereogenic centre in the molecule. Nevertheless, due to the observed centrosymmetric space group, both enantiomers are present in the crystal packing. The water molecule of crystallisation is located on a crystallographic inversion center. The molecule contains one five-membered ring (A) and three six-membered rings (benzyl ring B, benzylidene ring C and formylbenzyl ring D). All four rings are not coplanar: the dihedral angles between rings A and B, A and C, and A and D are 70.35 (9), 33.8 (1) and 60.30 (9)°, respectively. In the crystal, pairs of weak C—H⋯O interactions lead to the formation of centrosymmetric dimers. Additional C—H⋯O interactions link the dimers into chains along [011].

The crystal structure of the title compound, C 26 H 21 NO 3 Á-0.25H 2 O, reveals one stereogenic centre in the molecule. Nevertheless, due to the observed centrosymmetric space group, both enantiomers are present in the crystal packing. The water molecule of crystallisation is located on a crystallographic inversion center. The molecule contains one fivemembered ring (A) and three six-membered rings (benzyl ring B, benzylidene ring C and formylbenzyl ring D). All four rings are not coplanar: the dihedral angles between rings A and B, A and C, and A and D are 70.35 (9), 33.8 (1) and 60.30 (9) , respectively. In the crystal, pairs of weak C-HÁ Á ÁO interactions lead to the formation of centrosymmetric dimers. Additional C-HÁ Á ÁO interactions link the dimers into chains along [011].   Table 1 Hydrogen-bond geometry (Å , ). Symmetry codes: (i) Àx þ 1; Ày þ 1; Àz; (ii) x þ 1; y; z.
We thank the National Science Foundation of China (project No. 21072003 and 20872002) for financial support of this work. supplementary materials Acta Cryst. (2012). E68, o1184 [doi:10.1107/S1600536812012160] (E)-4-[(1-Benzyl-4-benzylidene-2,5-dioxopyrrolidin-3-yl)methyl]benzaldehyde 0.25-hydrate Tao Yu and Yimin Hu Comment Palladium-catalyzed coupling reactions have become an important tool in modern organic synthetical chemistry (Hu et al., 2011). A wide variety of active pharmaceutical compounds, natural substances and other complex organic molecules have been made economically accessible by this methodology (Hu et al., 2009a(Hu et al., , 2009b. Physiologically active dioxopyrrolidin-benzaldehyde derivatives are effective intermediates in the synthesis of many complex natural products (Pitchumani & Vijaikumar, 2010). We have reported some novel palladium-catalyzed inter-and intramolecular reactions of aryl halides with the olefins and enynes (Hu et al., 2010a(Hu et al., , 2010b. The reaction of N-acryloyl-N-benzylcinnamamide with 4-bromobenzaldehyde, in the presence of palladium(II) acetate and triphenylphosphine, in DMF at 373 K for 18 h, gave the unexpected title product.
After 18 h the reaction mixture was cooled to room temperature and the resulting yellow-orange mixture was diluted with Et 2 O (10 ml). The mixture was then washed with H 2 O (15 ml) and the aqueous layer was extracted with Et 2 O (20 ml).
The combined organic layers were dried over MgSO 4 , filtered, and concentrated in vacuo. The crude material was purified by flash column chromatography on silica gel (petroleum ether: EtOAc = 9:1) and recrystalized from EtOAc (yield 3.16 g, 80%). Colorless crystals suitable for X-ray diffraction were obtained by recrystallization from a solution of the title compound in ethyl acetate over a period of one week.    Rms deviation of fitted atoms = 0.0073 Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.