[Br:1][C:2]1[S:3][C:4]2[C:10]([O:11]S(C(F)(F)F)(=O)=O)=[C:9]([C@H:19]([O:25][C:26]([CH3:29])([CH3:28])[CH3:27])[C:20]([O:22][CH2:23][CH3:24])=[O:21])[C:8]([CH3:30])=[CH:7][C:5]=2[N:6]=1.CCCC[N+](CCCC)(CCCC)CCCC.[F-]>C1COCC1>[Br:1][C:2]1[S:3][C:4]2[C:10]([OH:11])=[C:9]([C@H:19]([O:25][C:26]([CH3:29])([CH3:28])[CH3:27])[C:20]([O:22][CH2:23][CH3:24])=[O:21])[C:8]([CH3:30])=[CH:7][C:5]=2[N:6]=1To a solution of (S)-ethyl 2-(2-bromo-5-methyl-7-(trifluoromethylsulfonyloxy)benzo[d]thiazol-6-yl)-2-tert-butoxyacetate (32): (500 mg, 0.938 mmol) in THF (5 ml) was added TBAF (1.0 M in THF, 4 ml) slowly. The reaction mixture was stirred at rt for 1 h. The reaction mixture was washed by a mixture of H2O (20 ml) and HOAc (200 ul), extracted by EtOAc, the organic phase was washed by sat. NaHCO3, dried over MgSO4, filtered, concentrated down and purified by silica gel column, eluting by 0-40% EtOAc in hexanes to give 75A (380 mg). LCMS-ESI+: calc'd for C16H20BrNO4S: 402.0 (M+H+); Found: 401.9 (M+H+).
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