2-[3-(1,3-Benzothiazol-2-yl)-2,2-dimethylpropyl]-2-methyl-2,3-dihydro-1,3-benzothiazole

In the title compound, C20H22N2S2, the five-membered thiazole ring of the 2-methyl-2,3-dihydro-1,3-benzothiazole unit has an envelope conformation. The dihedral angle between the planar [maximum deviation of 0.014 (1) Å for the S atom] benzothiazole ring system and the benzene ring is 78.37 (12)°. Two intramolecular C—H⋯S hydrogen bonds are observed, forming rings of graph-set motif S(6). In the crystal, the molecules are consolidated in pairs through N—H⋯N hydrogen bonds and are arranged parallel to the b axis.

In the title compound, C 20 H 22 N 2 S 2 , the five-membered thiazole ring of the 2-methyl-2,3-dihydro-1,3-benzothiazole unit has an envelope conformation. The dihedral angle between the planar [maximum deviation of 0.014 (1) Å for the S atom] benzothiazole ring system and the benzene ring is 78.37 (12) . Two intramolecular C-HÁ Á ÁS hydrogen bonds are observed, forming rings of graph-set motif S(6). In the crystal, the molecules are consolidated in pairs through N-HÁ Á ÁN hydrogen bonds and are arranged parallel to the b axis.   Table 1 Hydrogen-bond geometry (Å , ).  properties, such as analgesic, anti-viral, anti-bacterial, anti-inflammatory, anti-cancer, anti-diabetic and anti-HIV activities (Prabhu et al., 2011;Chaudhary et al., 2010;Kaur et al., 2010). The title compound was an unexpected product obtained during the synthesis of different benzothiazoles derivatives to study their bioactive potential and to establish the structureactivity relationship (SAR).

Experimental
A solution of dimedone (5,5-dimethylcyclohexane-1,3-dione; 500 mg, 3.5 mmol) and 2-aminothiophenol (0.384 ml, 3.5 mmol) in a mixture of acetic acid-ethanol (1:1 v/v, 15 ml) was stirred for 4 h. Progress of the reaction was monitored by thin layer chromatography in hexane:ethyl acetate (7:3 v/v) solvent system. After completion, the reaction mixture was dried under vacuum. Flash chromatography yielded the title compound in 55% yield (690 mg). Slow evaporation of an acetone/hexanes solution (1:1 v/v) yielded suitable crystals for single-crystal X-ray diffraction studies. All the starting material and solvents were purchased from commercial suppliers and used without purification.

Refinement
C-bound H atoms were positioned geometrically with C-H = 0.93-0.96 Å and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. The H atom on the nitrogen atom was located in a difference

Figure 1
The molecular structure of the titke compound with displacement ellipsoids drawn at the 30% probability level.
Hydrogen atoms not involved in intramolecular hydrogen bonds (dashed lines) are omitted. 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.