N-[(1S,2S)-2-Amino-1,2-diphenylethyl]-4-methylbenzenesulfonamide [(S,S)-TsDPEN]

The crystal structure of the title compound, C21H22N2O2S, shows a network of N—H⋯N and N—H⋯O hydrogen bonds. The tolyl and 1-phenyl rings are almost mutually coplanar [7.89 (9)°], while the 2-phenyl ring makes a dihedral angle of 50.8 (1) ° with the 1-phenyl ring. An intramolecular N—H⋯N hydrogen bond stabilizes the molecular conformation.

The crystal structure of the title compound, C 21 H 22 N 2 O 2 S, shows a network of N-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds. The tolyl and 1-phenyl rings are almost mutually coplanar [7.89 (9) ], while the 2-phenyl ring makes a dihedral angle of 50.8 (1) with the 1-phenyl ring. An intramolecular N-HÁ Á ÁN hydrogen bond stabilizes the molecular conformation.

Related literature
For the synthesis of the title compound, see: Vanino (1923);Mistryukov (2002). The title compound was synthesized as a ligand for Ru-catalyzed asymmetric transfer hydrogenations. Similar to BINAP introduced by the same author, the synthesized diamine permits highly enantioselective asymmetric hydrogenation reactions, see: Noyori (1996 Table 1 Hydrogen-bond geometry (Å , ). crystallization. After conversion to the free base, the (S,S)-1,2-diphenylethylenediamine is reacted with p-toluenesulfonyl chloride to give the desired product as colorless crystals. The crystal structure is characterized by a network consisting of the three following hydrogen bonds: N11-H11···N20 (2.09 Å), N20-H20B···O10 (2.17 Å) and N20-H20A···N11 (2.31 Å). The first two bonds build the network to a second molecule while the last one stabilizes the molecular conformation.

Experimental
The title compound was prepared from hydrobenzamide (Vanino, 1923) as follows: To a suspension of hydrobenzamide (66 g, 0.22 mol) in dry DMSO (100 ml) was added solid NaOH (1.2 g, 0.03 mol) under argon atmosphere and vigorous stirring.
After 5 min, the mixture was heated to 323 K and held at this temperature for 1 h. Then, the reaction mixture was heated to 403 K and stirred at that temperature for another 3 h. The mixture was cooled down to 353 K and diluted with ethanol and ammonia (28% in water). For completion of the crystallization, the mixture was allowed to stand at room temperature for 20 h. The crystalline isoamarine was filtered off and washed with 2-propanol (Mistryukov, 2002). Yield: 57.2 g (87%, Lit.:90%), m.p.: 474 K (Lit.: 471-473 K). In an argon atmosphere a mixture of isoamarine (50 g, 0.17 mol), pieces of aluminium foil (13.5 g, 0.5 mol), and HgCl 2 (3 g, 0.011 mol) were suspended in dry THF (300 ml). The suspension was stirred for 15 min. Then, water (9 ml) in THF (25 ml) was added during 1.5 h. After 2 h, another portion of water (25 ml) was added and the mixture was allowed to stand for 20 h. A concentrated solution of aqueous ammonia (50 ml) was added and the mixture was set aside for another 24 h before it was filtered. The filtrate was concentrated and the distillate was used to wash the residue on the filter. The obtained filtrate was also concentrated and combined with the remainder obtained in the first evaporation. The resulting oil was dissolved in a mixture of methanol (150 ml), concentrated HCl (75 ml) and water (50 ml). The crystaline dihydrochloride was filtered off, washed with dioxane and dried. To obtain the free base, the salt was dissolved in water (100 ml), NaOH was added and the solution was extracted four times with CHCl 3 . The combined organic layers were concentrated to dryness (see Mistryukov (2002)). Yield: 19.0 g (53%, Lit.: 78%), m.p.: 354 K (Lit.: 355 K). The obtained diamine (14.5 g, 0.068 mol) was dissolved in ethanol (77 ml) and warmed to 343 K. To this solution, L-(+)-tartaric acid (10.2 g, 0.068 mol) dissolved in hot (343 K) ethanol (77 ml) was added. The mixture was allowed to cool to ambient temperature before filtration. The crystals were washed with ethanol and dried in vacuo. The salt was then dissolved in boiling water (77 ml), ethanol (77 ml) was added and the mixture was allowed to cool slowly to room temperature. This and 8 ml of 50% aqueous solution of NaOH were added dropwise. The solution was extracted with CH 2 Cl 2 , the combined organic layers were washed with brine and dried over anhydrous Na 2 SO 4 . The solvent was evaporated in vacuo. From the combined filtrates and mother liquors, the (R,R)-diamine can be obtained in a similar fashion by crystallization with D-(-)-tartaric acid. Yield: 3.2 g (44%, Lit.: 57-66%), m.p.: 356 K, Lit.: 356 K, [α] D 23 : -101.9° (MeOH, c=1.0), Lit.: -106.0°( MeOH, c=1.1). For the tosylation, (S,S)-1,2-diphenylethylenediamine (0.3 g, 1.41 mmol) was dissolved in dry CH 2 Cl 2 (3 ml) and Et 3 N (320 µL) was added. Then, p-toluenesulfonyl chloride (0.256 g, 1.41 mmol) dissolved in dry CH 2 Cl 2 (9 mL) was added dropwise. After 30 min of stirring, the solution was diluted with CH 2 Cl 2 to twice its volume and washed with saturated NaHCO 3 , brine and dried over anhydrous Na 2 SO 4 . After evaporation of the solvent, the product was purified by flash chromatography on silica (petroleum ether/ethyl acetate, 2:3) and subsequently recrystallized from benzene. Yield:

Refinement
Hydrogen atoms attached to carbons were placed at calculated positions with C-H = 0.95 Å (aromatic) or 0.98-0.99 Å (sp 3 C-atom). Hydrogen atoms attached to nitrogen were located in difference Fourier maps. All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2-1.5 times of the U eq of the parent atom). Fig. 1. View of compound I. Displacement ellipsoids are drawn at the 50% probability level.