Ethyl 2-benzenesulfonamido-4-methylpentanoate

In the title compound, C14H21NO4S, the O—S—O angle is 120.06 (11)°, with the S atom adopting a distorted tetrahedral geometry. In the crystal, N—H⋯O hydrogen bonds connect the molecules along the a axis, generating an infinite chain. The disordered C atoms of the isobutyl group were refined with the C—C distances restrained to 1.52 (1) Å and the occupancy ratio refined to 0.504 (3):0.496 (3).

In the title compound, C 14 H 21 NO 4 S, the O-S-O angle is 120.06 (11) , with the S atom adopting a distorted tetrahedral geometry. In the crystal, N-HÁ Á ÁO hydrogen bonds connect the molecules along the a axis, generating an infinite chain. The disordered C atoms of the isobutyl group were refined with the C-C distances restrained to 1.52 (1) Å and the occupancy ratio refined to 0.504 (3):0.496 (3).

Comment
We report the crystal structure of title compound in continuation to our work on synthesis of sulfonamide derived from amino acids (Arshad et al., 2010;Arshad et al., 2012).
The methylester moiety (C7/C8/O3/O4/C9/C10) is almost planer with r. m. s. deviation of 0.0113 (2) Å and is oriented at dihedral angle of 21.37 (13)° with respect to the aromatic ring (C1-C6). The S atom adopts a distorted tetrahedral geometry and the bond angles are in comparison with the already published compound 4-methyl-2-(2-nitrobenzenesulfonamido)pentanoic acid (Arshad et al., 2012). The crystal structure shows intermolecular N-H···O hydrogen bonds connecting the molecules to a chain running along the a axis (Table. 1  mmol) in dimethylformamide (5 mL). The mixture was stirred for 15 mins followed by addition of ethyliodide (0.135 g, 0.86 mmol). Stirring was continued for 3-4 h and then mixture was poured on ice, precipitate obtained was filtered off, washed with water and recrystalized in ethylacetate under slow evaporation to give yellow crystal.

Refinement
The early refinement showed that there are two conformations of isobutyl moiety (C11-C14). These were refined anisotropically with distance restraint and the occupancy ratio was found 0.504 (3)  The labelled molecular structure of (I) with 50% displacement ellipsoids.  Unit cell packing showing hydrogen bonds, drawn using dashed lines.

Ethyl 2-benzenesulfonamido-4-methylpentanoate
Crystal data C 14 H 21 NO 4 S M r = 299.38 Orthorhombic, P2 1 2 1 2 1 Hall symbol: P 2ac 2ab a = 5.3084 (3) Å b = 9.5507 (7) (9) Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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.