[CH3:1][O:2][C:3]([C:5]1[S:9][C:8]([C:10]2[CH:15]=[CH:14][C:13]([Cl:16])=[CH:12][CH:11]=2)=[N:7][C:6]=1[CH2:17][CH2:18][OH:19])=[O:4].[Br-].[K+].Cl[O-].[Na+].C(=O)(O)[O-].[Na+]>C(Cl)Cl.O.CC1(C)N([O])C(C)(C)CCC1>[CH3:1][O:2][C:3]([C:5]1[S:9][C:8]([C:10]2[CH:15]=[CH:14][C:13]([Cl:16])=[CH:12][CH:11]=2)=[N:7][C:6]=1[CH2:17][CH:18]=[O:19])=[O:4]
Dissolve 2-(4-chloro-phenyl)-4-(2-hydroxy-ethyl)-thiazole-5-carboxylic acid methyl ester (100 g, 336 mmol) in CH2Cl2 (2 L) and treat with potassium bromide (4.0 g, 33.6 mmol) and TEMPO (1.1 g, 7.0 mmol). Cool the solution to −10° C. and add a solution of sodium hypochlorite (1 L, 0.25 M in water) and aqueous sodium bicarbonate (1 L, 1.4 M). Stir the resulting slurry at 0° C. for 15 min and then dilute with water (3.2 L) and CH2Cl2 (1.3 L). Remove the organic solution and extract the aqueous phase with CH2Cl2 (1.3 L). Combine the organic solutions and wash with brine (1.3 L), then dry, filter, and concentrate to give (91.5 g, 92%) of the title compound. 1H NMR (400 MHz, CDCl3): δ 9.86 (t, J=1.5 Hz, 1H), 7.90 (dt, J=8.4, 4.4 Hz, 2H), 7.43 (dt, J=8.6, 4.4 Hz, 2H), 4.32 (d, J=1.8 Hz, 2H), 3.89 (s, 3H).
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