(2E)-1-(5-Chlorothiophen-2-yl)-3-(2,3-dimethoxyphenyl)prop-2-en-1-one

In the title compound, C15H13ClO3S, the chlorothiophene and dimethoxyphenyl groups are linked by a prop-2-en-1-one group. The C=C double bond exhibits an E conformation. The molecule is non-planar, with a dihedral angle of 31.12 (5)° between the chlorothiophene and dimethoxyphenyl rings. The methoxy group at position 3 is coplanar with the benzene ring to which it is attached, with a C—O—C—C torsion angle of −3.8 (3)°. The methoxy group attached at position 2 of the benzene ring is in a (+)synclinal conformation, as indicated by the C—O—C—C torsion angle of −73.6 (2)°. In the crystal, two different C—H⋯O intermolecular interactions generate chains of molecules extending along the b axis.

In the title compound, C 15 H 13 ClO 3 S, the chlorothiophene and dimethoxyphenyl groups are linked by a prop-2-en-1-one group. The C C double bond exhibits an E conformation. The molecule is non-planar, with a dihedral angle of 31.12 (5) between the chlorothiophene and dimethoxyphenyl rings. The methoxy group at position 3 is coplanar with the benzene ring to which it is attached, with a C-O-C-C torsion angle of À3.8 (3) . The methoxy group attached at position 2 of the benzene ring is in a (+)synclinal conformation, as indicated by the C-O-C-C torsion angle of À73.6 (2) . In the crystal, two different C-HÁ Á ÁO intermolecular interactions generate chains of molecules extending along the b axis.
ANP is thankful to Manipal Institute of Technology, Manipal University.

Comment
Chalcones represent one of the most abundant and ubiquitous group of natural products (Tomazela, et al., 2000). In the past few years, they have been shown to possess interesting biological properties and synthetic intermediates (Choudary, et al., 1999). In the title compound ( Fig. 1), the chlorothiophene and dimethoxyphenyl groups are linked by a prop-2-en-1-one group. The chlorothiophene and dimethoxyphenyl rings are non-planar with the dihedral angle 31.12 (5)°. The torsion angle C15-O3-C12-C11 is 3.7 (3)° indicating that the O3 methoxy group is coplanar with the attached benzene ring. The other methoxy group at O2 is in a + synclinal conformation as indicated by the torsion angle 73.6 (2)° for C14-O2-C13-C12. The C═C double bond exhibits an E conformation (Benmekhbi, et al., 2009). The crystal structure is stabilized by two different C-H···O intermolecular interactions generating chains of molecules along the b-axis (Fig. 2).

Experimental
To synthesizethe the title compound, 2-acetyl-5-chlorothiophene (0.01 mol) and 2,3-dimethoxybenzaldehyde (0.01 mol) were dissolved in methanol (60 ml). Sodium hydroxide (5 ml, 20%) was then added drop wise to the solution, and it was stirred for 2 h. The contents of the flask were poured into ice-cold water, and the resulting crude solid was collected by filtration. The compound was dried and re-crystallized twice from acetone.

Refinement
The H atoms were placed at calculated positions in the riding model approximation with C-H = 0.93 and 0.96 Å, for aryl and methyl H-atoms, respectively, with U iso (H) = 1.2 and 1.5U eq (C). Fig. 1. ORTEP (Farrugia, 1997) view of the title compound, showing 50% probability ellipsoids and the atom numbering scheme.