2-(Benzo[d]thiazol-2-ylsulfonyl)-1-(4-bromophenyl)ethanone

In the title molecule, C15H10BrNO3S2, the dihedral angle between the benzothiazole ring system and the benzene ring is 67.57 (12)°. The crystal structure is stabilized by weak intermolecular C—H⋯O interactions. In addition, there is an intermolecular Br⋯C [3.379 (3) Å] contact which is shorter than the sum of the van der Waals radii of these atoms.

In the title molecule, C 15 H 10 BrNO 3 S 2 , the dihedral angle between the benzothiazole ring system and the benzene ring is 67.57 (12) . The crystal structure is stabilized by weak intermolecular C-HÁ Á ÁO interactions. In addition, there is an intermolecular BrÁ Á ÁC [3.379 (3) Å ] contact which is shorter than the sum of the van der Waals radii of these atoms.

Comment
The existence of so many valence states of sulfur has generated selective and novel ways to affect oxidation, dehydration, and carbon-carbon bond formation (Loghmani-Khouzani et al., 2008). Recent methods that allow introduction of a sulfur constituent β to a carbonyl group have shown particular promise (Loghmani-Khouzani et al., 2009a,b;Suryakiran et al., 2007;Munoz et al., 2005). 2-(1,3-Benzothiazol-2-yl-sulfonyl)-1-(4-bromophenyl)ethanone as a new compound with sulfur atom β to the carbonyl group is of great importance in organic synthesis. β-Keto-sulfones are a very important group of intermediates as they are precursors for Michael and Knoevenagel reactions (Marco et al., 1995) and are used in the preparation of acetylenes, allenes, chalcones, vinyl sulfones, polyfunctionalized 4H-pyrans and ketones (Fuju et al., 1988). In addition, β-keto-sulfones can be converted into optically active β-hydroxy-sulfones, halomethyl sulfones and dihalomethyl sulfones (Ni et al., 2006). Halomethyl sulfones and dihalomethyl sulfones are very good α-carbanion stabilizing substituents and precursors for the preparation of alkenes, aziridines, epoxides, and β-hydroxy-sulfones (Grossert et al., 1984). Haloalkyl sulfones are useful in preventing aquatic organisms from attaching to fishing nets and ship hulls (Oishi et al., 1988). They also possess other biological properties such as herbicidal, bactericidal antifungal, algaecidal and insecticidal (Antane et al., 2004). Recently sulfone-linked heterocycles were prepared and have been showed antimicrobial activity (Padmavathi et al., 2008). We report here the crystal structure of the title compound as a precursor for synthesis of gem-difluoromethylene-containing heterocycle.
In the molecule of the title compound, (Fig. 1), a new thio-benzothiazole derivative, the bond lengths (Allen et al., 1987) and angles are within the normal values and are comparable to the related structures (Loghmani-Khouzani et al., 2008a,b).
The dihedral angle between the benzothiazole ring system and the benzene ring is 67.57 (12)°. An interesting feature of the crystal structure is the short intermolecular Br···C iv [3.379 (3) Å; (iv) -x, -y, 2 -z] contact which is shorter than the sum of the van der Waals radii of these atoms. The crystal structure is stabilized by weak intermolecular C-H···O interactions (Table 1, Fig. 2).

Experimental
Sodium carbonate (4.5 mmol) was added to a stirred solution of 2-mercaptobenzothiazol (3 mmol) in ethanol (15 mL) and water (15 mL) and stirred at room temperature for 30 min. 2-bromo-1-(4-bromophenyl)ethanone (3 mmol) was added to the reaction mixture and stirring was continued for 1 h. The reaction was monitored by TLC and after 60 min. showed the complete disappearance of starting materials. The reaction mixture was poured into 100 mL of 1 M HCl containing 50 g of crushed ice. The product was filtered under vacuum and the filtrate was washed with 10 mL ice-cold ethanol and 10 mL water. Recrystallization from petroleum ether and filtration gave 2-(Benzo[d]thiazol-2-ylthio)-1-(4-bromophenyl)ethanone.

Refinement
All of the hydrogen atoms were positioned geometrically [C-H = 0.93-0.97 Å] and refined using a riding model approximation with U iso (H) = 1.2 U eq (C). Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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 > 2sigma(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.