Bromoacetic Acid → 10-[2-[[2-(2-Hydroxyethoxy)ethyl]amino]-2-oxo-1-[(phenylmethoxy)methyl]ethyl]-1,4,7,10-tetraazacyclododecan-1,4,7-triacetic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 45.5 g of bromoacetic acid (0.327 mol) in 140 mL of H2O, kept under stirring at 0° C., 31.5 mL of 10N NaOH (0.315 mol) are added in 1 h to pH 6. The resulting solution is added drop by drop to a solution of 46 g of N-[2-(2-hydroxyethoxy)ethyl)]-α-[(phenylmethoxy)methyl]-1,4,7,10-tetraazacyclododecan-1-acetamide trihydrochloride (0.084 mol) in H2O (100 mL) and, at a constant reaction temperature of 0° C., 10N NaOH is slowly added to pH 10. The reaction mixture is heated to 50° C. for 48 h and 50 mL of 10N NaOH (0.5 mol) are added to keep a constant pH of 10. After cooling at room temperature, the mixture is filtered on a Millipore® filter, neutralized with 37% HCl (w/w), diluted to 1.5 L with H2O and electrodialyzed. When the electrodialysis is over, the solution is concentrated under vacuum to give an oily residue which is placed into a drier to give a glassy solid. The solid is triturated and dissolved with AcOEt (200 mL), filtered and dried again. The crude product is dissolved in H2O (150 mL) and percolated on Amberlite® XAD 16 resin (1000 mL) performing a gradient elution with H2O--MeOH. The fractions containing the pure product are collected and concentrated under vacuum to give 38.83 g of the desired product (0.063 mol).

Provenance & Evidence