Hydrochloric Acid → 5.5'-(2,3-dihydroxybutane-1,4-diyl)bis(formylazanediyl)bis(N1,N3-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide)

Participants

Reaction Steps

To a stirred solution of water (10 ml), methanol (5 ml) and potassium hydroxide (1.0 g, 16.4 mmol) was added N1,N3-bis(2,3-dihydroxypropyl)-5-formylamino-2,4,6-triiodoisophthalamide (Example 1a) (10.0 g, 13.6 mmol). To the clear solution was then added boric acid (0.59 g, 9.5 mmol). The pH was continuously maintained at pH 12.6 by addition of potassium hydroxide (10 M) and 1,3-butadiene diepoxide (0.40 g, 4.7 mmol) was added. The pH of the solution was continuously maintained within the interval from 12.6 to 13 by addition of solid boric acid for 5 hours and then left over the weekend. The solution was neutralized by addition of hydrochloric acid (18% w) and then treated with ion exchangers (AMB200C, 20 ml) and (IRA67, 20 ml). The resins were removed by filtration and rinsed with water and the combined aqueous volume was reduced in vacuo. The crude product was purified by preparative HPLC (column Phenomenex Luna C18 10 μm 250×50.0 mm, solvents: A=water and B=acetonitrile; gradient 0-10% B over 60 min; flow 50.0 ml/ min, UV detection at 214 nm and 254 nm). After freeze drying 3.1 g 5.5′-(2,3-dihydroxybutane-1,4-diyl)bis(formylazanediyl)bis(N1,N3-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide) (43% yield) was obtained.

Provenance & Evidence