[F:1][C:2]([F:15])([F:14])[C:3]([NH:5][C@@H:6]1[CH2:12][C@H:11]([CH3:13])[O:10][CH:8](O)[CH2:7]1)=[O:4].[N+](C1C=CC(C([Cl:25])=O)=CC=1)([O-])=O>N1C=CC=CC=1>[F:1][C:2]([F:15])([F:14])[C:3]([NH:5][C@@H:6]1[CH2:12][C@H:11]([CH3:13])[O:10][CH:8]([Cl:25])[CH2:7]1)=[O:4]To a solution of 1 g of compound (IX) in 10 ml of anhydrous pyridine, 2 g of p-nitrobenzoyl chloride were added. After 12 hours at room temperature, the reaction mixture was poured onto ice and the resulting precipitate was washed with water until the water was neutral. The resulting crude 1-p-nitrobenzoate (mixture of α and β anomer) was dried over phosphorus pentoxide for several hours under vacuum, and then dissolved in dry methylene dichloride and saturated at 0° with anhydrous hydrogen chloride. The precipitated p-nitrobenzoic acid was filtered off under anhydrous conditions, and the 1-chloro derivative (II) was obtained in quantitative yield by evaporation of the solvent. Compound (II) can be used for the ensuing condensation reaction without further purification.
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