N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-4-fluorobenzenesulfonamide

In the title compound, C14H12FNO4S, the dihedral angle between the aromatic rings is 50.26 (9)° and the C—S—N—C bond adopts a gauche conformation [torsion angle = −68.12 (15)°]. The dihydrodioxine ring is disordered over two orientations, which both approximate to half-chairs, in a 0.880 (7):0.120 (7) ratio. In the crystal, N—H⋯O hydrogen bonds link the molecules into C(4) chains propagating in [100]. Weak C—H⋯O and C—H⋯F interactions consolidate the packing.

Experimental 0.2 g of 6-amino 1,4-benzodioxan was dissolved in 15 ml dichloromethane and 0.25 g of 4-fluorobenzene sulfonyl chloride was added to the mixture, which was stirred at room temperature overnight. The pH was maintained at 8-9 with triethyamine. On completion of reaction (after TLC) the pH was adjusted to 1-2 with 1 M HCl solution. The organic fraction was collected and the solvent was allowed to evaporate at room temperature. Colourless prisms of (I) were obtained in 95% yield.

Refinement
The N-bond H atom was located in a difference map and its position was freely refined. The C-bound H atoms were placed in calculated positions (C-H = 0.93-0.97 Å) and refined as riding. The constraint U iso (H) = 1.2U eq (C,N) was applied.

Figure 1
The molecular structure of (I), showing displacement ellipsoids at the 50% probability level. Only the major disorder component is shown.

Figure 2
The partial packing diagram for (I) showing the formation of C(4) chains: hydrogen bonds are shown as double-dashed lines and all C-bound H atoms are omitted for clarity. Symmetry code: (i) x-1, y, z.

N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-4-fluorobenzenesulfonamide
Crystal data 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (