2,5-dibromopentanoyl Bromide → N,N'-bis[2-(acetyloxy)-1-[(acetyloxy)methyl)ethyl]-5-[(2,5-dibromo-1-oxopentyl)amino]-2,4,6-triiodo-1,3-benzenedicarboxamide

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Reaction Steps

2,5-Dibromopentanoyl bromide prepared as described in example 8a (15.9 g, 49.3 mmol) was added dropwise to a stirred solution of N,N'-bis[2-(acetyloxy)-1-[(acetyloxy)methyl]ethyl]-5-amino-2,4,6-triiodo-1,3-benzenedicarboxamide (33 g, 37.8 mmol) in dimethylacetamide (250 ml) at 0°. After the addition, the reaction mixture was stirred at 0° for 1 hour, and then at room temperature for 22 hours. The solution was then added slowly dropwise to a well stirred mixture of ice-water (2 L), when a white solid separated out. This was collected by filtration, washed with ice-water (3×50 ml), and dried in vacuo to obtain the crude product (40.1 g, 91.5% pure). Recrystallization from ethyl acetate furnished analytically pure N,N'-bis[2-(acetyloxy)-1-[(acetyloxy)methyl]ethyl]-5-[(2,5-dibromo-1-oxopentyl)amino]-2,4,6-triiodo-1,3-benzenedicarboxamide as an off-white crystalline compound (35.3 g, 84% yield), m.p. 240°-243°.

Provenance & Evidence