C(=O)([O-])O.[Na+].[NH:6]1[CH2:11][CH2:10][C:9]([C:12]2[CH:17]=[CH:16][C:15]([N:18]3[CH2:22][C@H:21]([CH2:23][NH:24][C:25](=[O:27])[CH3:26])[O:20][C:19]3=[O:28])=[CH:14][CH:13]=2)=[CH:8][CH2:7]1.[C:29]([O:32][CH2:33][C:34](Cl)=[O:35])(=[O:31])[CH3:30].CO>CC(C)=O.O.ClCCl>[C:29]([O:32][CH2:33][C:34]([N:6]1[CH2:11][CH2:10][C:9]([C:12]2[CH:17]=[CH:16][C:15]([N:18]3[CH2:22][C@H:21]([CH2:23][NH:24][C:25](=[O:27])[CH3:26])[O:20][C:19]3=[O:28])=[CH:14][CH:13]=2)=[CH:8][CH2:7]1)=[O:35])(=[O:31])[CH3:30]Sodium hydrogen carbonate (1.89 g) was added to a stirred solution of Example 2 (1.92 g) in a mixture of acetone (25 ml) and water (12.5 ml), and the mixture cooled to 0-3° C. Acetoxyacetyl chloride (1.23 g, 0.97 ml) was added dropwise over 5-10 mins. and the reaction mixture was stirred at 0-5° C. for 30 minutes then allowed to warm to ambient temperature over 1 hour. TLC (10% methanol in dichloromethane) showed complete reaction. The reaction mixture was diluted with water and extracted well with ethyl acetate. The organic phase was washed with brine and dried over anhydrous sodium sulfate. The title compound crystallized during evaporation of the solvent and was triturated with ether (yield=1.70 g, 91%).
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