Potassium Carbonate → N,N'-bis[2,3-bis(acetyloxy)propyl]-5-(3-bromo-2-oxo-1-piperidinyl]-2,4,6-triiodo-1,3-benzenedicarboxamide

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Reaction Steps

To a solution of N,N'-bis[2,3-bis(acetyloxy)propyl]-5-[(2,5-dibromo-1-oxopentyl)amino]-2,4,6-triiodo-1,3-benzenedicarboxamide of example 8a (20.7 g, 18.5 mmol) in N,N-dimethylacetamide (200 ml), was added powdered potassium carbonate (20 g, 92 mmol) and the mixture was stirred at room temperature for 5 hours. The resulting slurry was filtered and the filtrate freed of the solvent to obtain a light brown solid, which was redissolved in ethyl acetate (500 ml). The solution was washed with water (2×50 ml) and saturated aqueous sodium chloride (1×100 ml) and then dried over magnesium sulfate. The solvent was removed in vacuo and the crude product (18.1 g) purified by column chromatography over silica gel to obtain pure N,N'-bis[2,3-bis(acetyloxy)propyl]-5-(3-bromo-2-oxo-1-piperidinyl]-2,4,6-triiodo-1,3-benzenedicarboxamide as a white solid (14.04 g, 80% yield), m.p. 232°-35°.

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