N-(Phenylsulfonyl)-l-asparagine

In the title compound, C10H12N2O5S, one of the sulfonyl O atoms is hydrogen bonded to the amido N atom of an adjacent molecule. There is also a weak hydrogen-bonding interaction between the other sulfonyl O atom and the secondary amino N atom. In addition, the amido O atom is also hydrogen bonded to a carboxyl O atom. These hydrogen-bonding interactions give rise to a layer structure parallel to the bc plane.

In the title compound, C 10 H 12 N 2 O 5 S, one of the sulfonyl O atoms is hydrogen bonded to the amido N atom of an adjacent molecule. There is also a weak hydrogen-bonding interaction between the other sulfonyl O atom and the secondary amino N atom. In addition, the amido O atom is also hydrogen bonded to a carboxyl O atom. These hydrogen-bonding interactions give rise to a layer structure parallel to the bc plane.

S1. Comment
Sulfonamides compounds have long been studied due to their biological activity. N-acylsufonamide derivatives of asparagine have synthesized and characterized (Koroniak et al., 2003). The title compound is also a sulfonamide derivative and synthesized in continuation of our studies for the synthesis of acyclic and cyclic sulfonamides (Arshad et al., 2008), (Arshad et al., 2009). In this sulfonamide derivative of L-asparagine ( Fig. 1), the molecule is twisted due to the tetrahedral geometries at S1, C7 and C9. One of the sulfonyl oxygen O2 is hydrogen-bonded to the amido nitrogen atom N2 of an adjacent molecule. The amido oxygen O6 also forms hydrogen bond with the carboxylate oxygen O4 of an adjacent molecule. There is a weak hydrogen bonding interaction between the other sulfonyl oxygen O1 and the secondary amino nitrogen N1 (Fig. 2). No significant intramolecular hydrogen bonding interaction is found in the molecule.

S2. Experimental
Asparagine (0.175 g, 1.32 mmol) was dissolved in distilled water (10 ml) in a round bottom flask (25 ml). The pH of the solution was adjusted at 8-9 using 1M, Na 2 CO 3 solution. Benzenesulfonyl chloride (0.169 ml, 0.234 g, 1.32 mmol) was suspended to the above solution and stirred at room temperature until all the benzenesulfonyl chloride was consumed.
The completion of the reaction was achieved when the suspension turned to a clear solution. Upon completion of the reaction, the pH was adjusted 1-2, using 1 N HCl solution. The precipitate obtained was filtered, washed with distilled water, dried and recrystalized in methanol to yield white crystals.

S3. Refinement
Hydrogen atoms were placed at calculated positions (C-H 0.93 to 0.97 Å) and were treated as riding on their parent carbon atoms, with U(H) set to 1.2-1.5 times U~eq~(C). The hydroxy H was refined with a restraint of 0.82 (1) Å. The Flack parameter refined to -0.01 (6)   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.  (7) 0.0059 (7) 0.0014 (6)  C9 0.0340 (8) 0.0315 (9) 0.0346 (9) 0.0006 (7) 0.0041 (7) 0.0053 (7)