Hydrochloric Acid → 2,5-Bis[4,10-dicarboxymethyl-1,4,7,10-tetraazacyclododecan-1-yl]hexan-1,6-dioic acid

Participants

Reaction Conditions

Reaction Steps

In a 250 mL RB flask the ester of Example 4 (1.77 g, 1.63 mmol) was dissolved in ethanol (30 ml) and water was added until the solution turned slightly turbid. The temperature was elevated to 100° C. and 1N LiOH (13 mL) was added. After maintaining the mixture at 100° C. for 7 hours, the reaction was stirred at 50° C. for a further 18 hours. The solution was adjusted to pH 0.5 with 5N HCl (aq), and the mixture was refluxed for 1.5 hours and stirred at ambient temperature for an additional 18 hours. The material was loaded onto a bed of AG5OW-X8 [80 mL, (H+ -form)] strongly acidic cation exchange resin. After rinsing with water (1100 mL), the target material was eluted from the bed using 0.25N NH4OH solution. The fractions containing the title product were combined and evaporated to afford 0.79 g (79%) as a glassy solid. 1H NMR (D2O) δ 3.81 (br, 2H), 3.58-2.78 (br, 40H), 2.135 (br, 2H), 1.85 (br, 2H). 13C NMR (D2O): 22.5, 23.1, 40.6, 46.4, 48.6, 54.5, 62.6, 170.3, 175.7. MS (FAB): m/e 719.4 (MH+).

Provenance & Evidence