[I:1]N1C(=O)CCC1=O.[CH2:9]([O:13][C:14]1[C:19]([C:20]([OH:22])=[O:21])=[CH:18][CH:17]=[CH:16][N:15]=1)[CH2:10][CH2:11][CH3:12]>FC(F)(F)C(O)=O.FC(F)(F)C(OC(=O)C(F)(F)F)=O>[CH2:9]([O:13][C:14]1[C:19]([C:20]([OH:22])=[O:21])=[CH:18][C:17]([I:1])=[CH:16][N:15]=1)[CH2:10][CH2:11][CH3:12]N-Iodosuccinimide (6.0 g, 26.7 mmol) was added to a solution of 2-n-butoxypyridine-3-carboxylic acid (Preparation 4; 3.46 g, 17.7 mmol) in trifluoroacetic acid (28 mL) and trifluoroacetic anhydride (7 mL) and the reaction heated under reflux in the absence of light, for 3 hours. The cooled reaction mixture was concentrated under reduced pressure and the residue dissolved in ethyl acetate. This solution was washed sequentially with water (2×), aqueous sodium thiosulfate solution, aqueous sodium citrate solution, 2 N hydrochloric acid, and brine, then dried (MgSO4) and evaporated under reduced pressure. The solid was triturated with pentane, filtered, washed with additional pentane and dried, to give the title compound as a white solid (3.86 g, 68%).
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