[CH:1]1([S:4]([C:16]2[CH:21]=[CH:20][C:19]([N+:22]([O-])=O)=[CH:18][CH:17]=2)(=[N:6][S:7]([CH2:10][CH2:11][Si:12]([CH3:15])([CH3:14])[CH3:13])(=[O:9])=[O:8])=[O:5])[CH2:3][CH2:2]1.Cl.[OH-].[Na+].C(OCC)(=O)C>O1CCCC1.[Cl-].[Ti+3].[Cl-].[Cl-]>[NH2:22][C:19]1[CH:20]=[CH:21][C:16]([S:4]([CH:1]2[CH2:3][CH2:2]2)(=[N:6][S:7]([CH2:10][CH2:11][Si:12]([CH3:14])([CH3:15])[CH3:13])(=[O:8])=[O:9])=[O:5])=[CH:17][CH:18]=1320 mg of (RS)—S-cyclopropyl-S-(4-nitrophenyl)-N-[2-(trimethylsilyl)ethyl-sulfonyl]sulfoximide is dissolved in 5 ml of tetrahydrofuran. While being cooled with ice, 7.2 ml of an approximately 10% by weight solution of titanium(III) chloride in 20-30% by weight of hydrochloric acid is added in drops. The solution is stirred for 16 hours at room temperature and poured onto ice. The pH is set at 8-9 with 15% sodium hydroxide solution. After ethyl acetate is added, the mixture is vigorously stirred. The precipitate is suctioned off and washed with 100 ml of ethyl acetate. The filtrates are combined, dried and concentrated by evaporation. After purification by flash chromatography, 215 mg of (RS)—S-(4-aminophenyl)-S-cyclopropyl-N-[2-(trimethylsilyl)ethylsulfonyl]sulfoximide is obtained.
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