[CH2:1]([C:3]([OH:17])([CH2:15][CH3:16])[CH:4]([NH:7][C:8](=[O:14])[O:9][C:10]([CH3:13])([CH3:12])[CH3:11])[CH2:5][OH:6])[CH3:2].Cl[O-].[Na+].Cl([O-])=[O:22].[Na+].C(O)(=O)CC(CC(O)=O)(C(O)=O)O>P([O-])([O-])([O-])=O.C(#N)C>[C:10]([O:9][C:8]([NH:7][CH:4]([C:3]([CH2:15][CH3:16])([OH:17])[CH2:1][CH3:2])[C:5]([OH:22])=[O:6])=[O:14])([CH3:12])([CH3:11])[CH3:13]
tert-Butyl 2-ethyl-2-hydroxy-1-(hydroxymethyl)butylcarbamate (5.80 g) obtained in Example 36a) and 2,2,6,6-tetramethyl-1-piperidinyloxy (0.73 g) were dissolved in phosphate buffer (pH 6.8, 100 ml) and acetonitrile (100 ml). While the mixture was warmed to 35° C., an aqueous sodium hypochlorite solution (1.3 ml) and an aqueous solution (20 ml) of sodium chlorite (6.4 g) were simultaneously added dropwise thereto over 2 hours, respectively. The reaction mixture was mixed at 35° C. overnight, and returned to room temperature. The solution was acidified by adding a 5% aqueous citric acid solution and extracted three times with ethyl acetate. The extracts were combined and dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified with silica gel column (ethyl acetate/hexane=1/1 to 3/1) to obtain the title compound as colorless powder (0.28 g, 24%).
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