Methyl 2-(4-acetamidobenzenesulfonamido)benzoate

The molecule of the title compound, C16H16N2O5S, has the shape of the letter V but with a small twist; the dihedral angle formed between the benzene rings is 79.66 (9)°. The presence of an intramolecular N—H⋯O hydrogen bond, leading to an S(6) ring, correlates with the near coplanarity of the carboxylate ester group with the benzene ring to which it is connected. The acetamide residue is slightly twisted out of the plane of its benzene ring [C—C—N—C = 13.1 (3)°]. In the crystal, supramolecular chains along the a axis are mediated by N—H⋯O hydrogen bonds. These are connected into layers via C—H⋯O interactions.

The molecule of the title compound, C 16 H 16 N 2 O 5 S, has the shape of the letter V but with a small twist; the dihedral angle formed between the benzene rings is 79.66 (9) . The presence of an intramolecular N-HÁ Á ÁO hydrogen bond, leading to an S(6) ring, correlates with the near coplanarity of the carboxylate ester group with the benzene ring to which it is connected. The acetamide residue is slightly twisted out of the plane of its benzene ring [C-C-N-C = 13.1 (3) ]. In the crystal, supramolecular chains along the a axis are mediated by N-HÁ Á ÁO hydrogen bonds. These are connected into layers via C-HÁ Á ÁO interactions.

Comment
As part of on-going structural studies of sulfonamides (Sharif et al., 2010;Khan et al., 2010), the crystal structure of the title compound, (I), is described. Interest in these derivatives relate to their wide use in the treatment of certain infections caused by Gram-positive and Gram-negative microorganisms, some fungi, and certain protozoa (Korolkovas, 1988;Mandell & Sande, 1992).
The molecule of (I), Fig. 1, has an approximate V-shape with the dihedral angle formed between the benzene rings being 79.66 (9) °. The carboxylate ester substituent is co-planar with the benzene ring to which it is connected [the C1-C2-C7-O3 and torsion angle is 2.9 (2) °] but the acetamide residue is slightly twisted out of the plane [C11-C12-N2-C15 = 13.1 (3) °]. The planarity observed for the carboxylate ester group is readily rationalized in terms of an intramolecular N-H···O hydrogen bond, Table 1, which seals a six-membered ring. The most prominent intermolecular contact in the crystal structure is also of the type N-H···O, Table 1, and this serves to link molecules into a linear supramolecular chain along the a axis, Fig. 3. Chains are linked into layers in the ab plane via C-H···O contacts, Table   1, and these stack along the c axis via inter-digitation of the benzoate ester groups; there is no evidence for significant π-interactions between these, however.

Experimental
To methyl anthranilate (260 µl, 2 mmol) in water (10 ml) was added p-toluene sulfonyl chloride (380 mg, 2 mmol). With stirring at room temperature, the pH of the solution was maintained with 3% Na 2 CO 3 . The progress of the reaction was monitored by TLC. On completion of the reaction, the pH was adjusted to 3 with 3 N HCl. The white precipitates that formed were filtered, washed with distilled water and crystallized from methanol to yield colourless blocks of the title compound.

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.93-0.96 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (C).   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 > 2σ(F 2 ) is used only for calculating Rfactors(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.