HCID 20038264, compound → HCID 19693325, compound

Participants

Reaction Steps

A solution of [((7-aminoheptyl)imino)bis(ethylenenitrilo)]tetraacetic acid (0.72g, 1.6 mmol) in saturated aqueous sodium bicarbonate (15 ml) was cooled in an ice bath and N-carboxymethoxymaleimide (prepared according to Helv. Chim. Acta, 58, 531 [1975]) (0.25 g, 1.6 mmol) was added in one portion. After stirring 20 minutes the ice bath was removed and stirring was continued for 30 minutes. The solution was brought to ph≈6 with 1N HC1 and concentrated under reduced pressure. The residue was chromatographed on a 2×30 cm column of Bio-Rad AG 1×8 ion exchange resin in the formate form (gradient elution, 0-1M formic acid) to provide 0.61 g of slightly impure product. This material was rechromatographed as above to yield pure [((7-maleimidoheptyl)imino)bis(ethylenenitrilo)]tetraacetic acid (0.42g, 50%).

Provenance & Evidence