(E)-(2,4-Dichlorophenyl)[2-hydroxy-6-(methoxyimino)cyclohex-1-enyl]methanone

The title compound, C14H13Cl2NO3, was obtained as the product of an attempted synthesis of herbicidally active compounds containing oxime ether and cyclohexenone groups. In the crystal structure, the molecule adopts an endocyclic enol tautomeric form and the cyclohexene ring adopts a distorted envelope form. The oxime ether group has an E configuration, with the methoxy group anti to the ortho-chloro substitutent. Intramolecular O—H⋯O and intermolecular C—H⋯O hydrogen bonds are found in the crystal structure.

The title compound, C 14 H 13 Cl 2 NO 3 , was obtained as the product of an attempted synthesis of herbicidally active compounds containing oxime ether and cyclohexenone groups. In the crystal structure, the molecule adopts an endocyclic enol tautomeric form and the cyclohexene ring adopts a distorted envelope form. The oxime ether group has an E configuration, with the methoxy group anti to the orthochloro substitutent. Intramolecular O-HÁ Á ÁO and intermolecular C-HÁ Á ÁO hydrogen bonds are found in the crystal structure.
The title compound consists of 2,4-dichlorobenzoyl and cyclohexenone oxime O-methyl ether moieties. It has several possible tautomers in solution due to the existence of a 1,3-dione structure (Huang et al. 2002). The title molecule adopts an endocyclic enol tautomeric form in the crystal structure, i.e. the carbonyl group of the cyclohexenone unit is enolized. The cyclohexene ring adopts a distorted envelope form. The oxime ether is in an E configuration, with the methoxy group being anti to the substitutent group at the C-11 position (Fig. 1). The bond length of C6=N1 is 1.284 (3) Å and the C=N-O angle is 110.89 (17)°, which is close to the value in 5-chloro-2-methylthio-3H-indole-3-one 3-oxime O-methyl ether, (111.3 (5)°) (Beddoes et al., 1992), showing that the C6=N1 bond is conjugated with the C8=C11 and C9=O1 bonds.
In addition, two weak intermolecular C-H···O hydrogen bonding contacts, which form columns along the b axis, are found in the packing structure (Table 1 and Fig. 2).
The mixture was diluted with 100 ml of water and extracted with 30 ml e thyl acetate three times. The combined organic layer was dried with anhydrous magnesium sulfate and purified by column chromatography (ethyl acetate:petroleum ether = 1:12) to afford the title compound (70% yield). A crystal suitable for X-ray analysis was obtained by recrystallization of the product with acetone/pentane (1:10) at room temperature over a period of 3 d.

Refinement
All H atoms were located in difference Fourier maps and refined independently with isotropic displacement parameters.
supplementary materials sup-2 Figures Fig. 1. Perspective view of the title complex with atom numbering scheme. Thermal ellipsoids are shown at 30% probability level.   Geometric parameters (Å, °)