[Br:1][C:2]1[S:6][C:5]([CH2:7][S:8][CH2:9][CH2:10][C:11]([O:13][CH3:14])=[O:12])=[N:4][CH:3]=1.CO.[OH2:17].[OH2:18].O.O.O.O.C(O[O-])(=O)C1C(=CC=CC=1)C([O-])=O.[Mg+2]>C(Cl)Cl.[O-]S([O-])(=S)=O.[Na+].[Na+].O>[Br:1][C:2]1[S:6][C:5]([CH2:7][S:8]([CH2:9][CH2:10][C:11]([O:13][CH3:14])=[O:12])(=[O:18])=[O:17])=[N:4][CH:3]=1The product of Step 2 (1.45 g, 4.90 mmol) was taken up in CH2Cl2 (30 mL)/MeOH (15 mL), and magnesium monoperoxyphthalate hexahydrate (4.54 g, 7.34 mmol) was added. The reaction was stirred at room temperature for 2 h. The yellow slurry was diluted with aqueous 10% Na2S2O3 and water and extracted with CH2Cl2 (2×). The combined organic layers were washed with saturated aqueous NaHCO3, dried (MgSO4), filtered and evaporated. Flash chromatography (0-50% ethyl acetate in hexanes) afforded methyl 3-{[(5-bromo-1,3-thiazol-2-yl)methyl]sulfonyl}propanoate (1.53 g, 95%) as a white solid. MS ESI: [M+H]+ m/z 327.9/329.9.
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