Reaction SMILES: [CH3:1][CH:2]([CH3:27])[C@@H:3]([NH:7][S:8]([C:11]1[CH:26]=[CH:25][C:14]2[N:15]=[C:16]([S:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH3:24])[S:17][C:13]=2[CH:12]=1)(=[O:10])=[O:9])[C:4]([OH:6])=[O:5].[C:28]1([C:34]([C:37]2[CH:42]=[CH:41][CH:40]=[CH:39][CH:38]=2)=[N+]=[N-])[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1>CC(C)=O>[C:28]1([CH:34]([O:5][C:4](=[O:6])[C@H:3]([NH:7][S:8]([C:11]2[CH:26]=[CH:25][C:14]3[N:15]=[C:16]([S:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH3:24])[S:17][C:13]=3[CH:12]=2)(=[O:10])=[O:9])[CH:2]([CH3:1])[CH3:27])[C:37]2[CH:38]=[CH:39][CH:40]=[CH:41][CH:42]=2)[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1
Reactant: CCCCCCSc1nc2ccc(S(=O)(=O)N[C@@H](C(=O)O)C(C)C)cc2s1
Reactant: [N-]=[N+]=C(c1ccccc1)c1ccccc1
Solvent: CC(C)=O
Product: CCCCCCSc1nc2ccc(S(=O)(=O)N[C@@H](C(=O)OC(c3ccccc3)c3ccccc3)C(C)C)cc2s1
Temperature: 25 °C
Reaction time: 12 h
Yield: 102.4 %

Procedure:
(2R)-3-Methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl)amino]butanoic acid (7.9 g, 0.018 mol) prepared in Example 18-7 was dissolved in acetone (100 mL) and the solution was added to diphenyldiazomethane (0.02 mole) acetone solution at RT. The reaction solution was stirred for 12 hours at RT, concentrated and crystallized with n-hexane to give 11.0 g (100%) of (2R)-3-methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl)amino]butanoic acid diphenylmethylester. (2R)-3-Methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl)amino]butanoic acid diphenylmethylester (1.0 g, 1.7 mmol) was dissolved in acetone (3 mL). K2CO3 (0.47 g, 2.0 equi.) and ethylbromoacetate (0.204 mL, 1.1 equi.) were added to the solution and then, the reaction solution was reacted at 50° C. for 12 hours. Then, the reaction solution was distilled under reduced pressure to remove the solvent and the product was extracted with water/ethylacetate. The organic phase was treated with anhydrous MgSO4 to remove the solvent and give (2R)-3-methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl) ethoxycarbonylmethyl amino]butanoic acid diphenylmethylester (1.14 g, 100%). Without further purification, the compound was dissolved in CH2Cl2 (50 mL). Then, TFA (1.29 mL, 10.0 eq) and anisole (0.55 mL, 3 eq) were added and the reaction solution was subjected at PT for 2 hours. Then, the solvent was removed from the solution, which was then treated with n-hexane to give (2R)-3-methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl) ethoxycarbonylmethyl amino]butanoic acid (1.0 g). The product was dissolved in dichloromethane (25 ml) and the solution was cooled down to 0° C. Oxalylchloride (0.73 mL, 5 equi.) and DMF of catalytic amount were added, and reacted for 3 hours at RT. Then, the reaction solution was distilled under reduced pressure to remove solvent and dried under reduced pressure to give (2R)-3-methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl) ethoxycarbonylmethyl amino]butanoic acid chloride which was then dissolved in THF (20 mL). Hydroxylamine hydrochloride (1.16 g, 10 equi.) and NaHCO3 (2.83 g, 12 equi.) were dissolved in THF/H2O (20 mL/20 mL) and cooled down to 0° C. to prepare hydroxylamine solution. The acid chloride/THF solution thus obtained was slowly added to the hydroxylamine solution. After 1 hour, the solvent was removed from the reaction solution. The product was extracted with ethylacetate (50 mL) and then, washed with H2O and 0.1N HCl and dried over MgSO4 to prepare 1.23 g of N-hydroxy-(2R)-3-methyl-2-[(2-n-hexylthiobenzthiazol-6-sulfonyl)ethoxycarbonyl methylamino]butyric amide.