(6Z)-4-Bromo-6-{[(2-hydroxyethyl)amino]methylidene}cyclohexa-2,4-dien-1-one

The title molecule, C9H10BrNO2, excluding methylene H atoms and the C—OH group, is essentially planar, with a maximum deviation of 0.037 (2) Å for the N atom. The N—C—C—O torsion angle is −63.1 (3)°. The molecular structure is stabilized by a weak intramolecular N—H⋯O(carbonyl) hydrogen bond, forming an S(6) motif. In the crystal, molecules are linked by O—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional network.

As an extension of our work on the reactivity of primary aminoalcohols in three-component reactions, the title compound has been isolated as a secondary product from the one-pot reaction of (2E)-3-(4-methylphenyl)-1-phenylprop-2-en-1-one (chalcone), 5-bromo-2-hydroxybenzaldehyde and aminoethanol under mild conditions. As shown in Fig. 1, excluding methylene H atoms and the C-OH group, the molecule is essentially planar, with a maximum deviation of 0.037 (2) Å for N1. The N1-C8-C9-O2 torsion angle is -63.1 (3)°. The bond lengths (Allen et al., 1987) and angles have normal values.
The molecular structure is stabilized by a weak intramolecular N-H···O hydrogen bond, which generates an S(6) ring motif (Bernstein et al., 1995;Etter et al., 1990). In addition, intermolecular O-H···O and C-H···O hydrogen bonds (Table 1, Fig. 2) contribute to the stability of the crystal structure, linking the molecules into a three-dimensional network.

Experimental
The title compound has been obtained as a secondary product from a multicomponent reaction mixture of (2E)-3-(4methylphenyl)-1-phenylprop-2-en-1-one (0.01mol), 5-bromo-2-hydroxybezaldehyde (0.01mol) and aminoethanol (0.01mol). The mixture was heated at 353 K in ethanol for 4 h, monitored by TLC until the reaction was completed and then cooled to room temperature. The solvent was evaporated under vacuum and the residual oil was triturated with water to afford a brown precipitate which was filtered off, washed with water and dried in a desiccator. Pale yellow plate crystals for x-ray diffraction were obtained by dissolving the product in ethanol at room temperature and leaving it to evaporate slowly over four days. 43% yield; m.p. 355 K.

Figure 1
The molecular structure, showing displacement ellipsoids drawn at the 50% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.

(6Z)-4-Bromo-6-{[(2-hydroxyethyl)amino]methylidene}cyclohexa-2,4-dien-1-one
Crystal data C 9 H 10 BrNO 2 M r = 244.08 Monoclinic, P2 1 /n Hall symbol: -P 2yn a = 4.4534 (17) Å b = 11.523 (4) Å c = 18.212 (7) Å β = 95.703 (7) where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.50 e Å −3 Δρ min = −0.81 e Å −3 Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.