C(N(C(C)C)CC)(C)C.CC1(C)C2CC[C@@]1(CS([O:23][CH2:24][CH2:25][CH2:26][C@@:27]1([C:33]3[CH:38]=[CH:37][C:36]([Cl:39])=[C:35]([Cl:40])[CH:34]=3)[CH2:32][CH2:31][CH2:30][NH:29][CH2:28]1)(=O)=O)C(=O)C2.[C:42]1([C:48](Cl)=[O:49])[CH:47]=[CH:46][CH:45]=[CH:44][CH:43]=1>C(Cl)Cl>[Cl:40][C:35]1[CH:34]=[C:33]([C:27]2([CH2:26][CH2:25][CH2:24][OH:23])[CH2:32][CH2:31][CH2:30][N:29]([C:48]([C:42]3[CH:47]=[CH:46][CH:45]=[CH:44][CH:43]=3)=[O:49])[CH2:28]2)[CH:38]=[CH:37][C:36]=1[Cl:39]Diisopropylethylamine(5.7 mL, 3.27 mmol, 5.0 eq) was added to a mixture of camphorsulfonate salt (9) (3.4 g, 6.53 mmol) in CH2Cl2 (21 mL, 0.3 M) and followed by dropwise addition of PhCOCl (0.83 mL, 7.19 mmol, 1.1 eq). The solution was stirred at room temperature for 1 hour. The reacting mixture was diluted with CH2Cl2 (200 mL) and washed with brine, 1 M KHSO4, and saturated NaHCO3 then dried over MgSO4. The concentrated crude oil was purified by flash chromatography (CH2Cl2-MeOH/95:5) to give white solid (2.30 g, 89.8%).
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