N4,N7,N10 -Triscarboxymethyl-1,13-bisbenzyloxy-5,9-bisbenzyloxymethyl-4,7,10-triazatridecane (0.30 g, 0.4 mmol) was dissolved in methanol (15 ml), 10% Palladium on carbon (0.3 g) and ammonium formate (0.1 g) were added and the mixture was kept at 50° C. for 16 hours. The catalyst was filtered off and washed with methanol (5 ml). The filtrate was evaporated and the title compound was isolated as a white powder. Yield 0.14 g (95%). M.p. 173°-177° C. The structure was confirmed by 1H NMR and 13CNMR.
