Synthesis of dicarboxymethyl tetraazacyclododecane derivatives for polycondensation

Three different routes to synthesize selectively protected tetraaza macrocy cles bifunctionalized with carboxymethyl acid groups have been developed in order to obtain monomers for polycondensation. The first way has been carr ied out from cyclen, whose synthesis has been improved, requires 6 steps. T he second way allowed to obtain the bifunctional protected macrocycle from ethylenediamine and diethyl iminodiacetate in 2 steps. The last way has con sisted in synthesizing directly a monomer by cyclization from ethylenediami netetraacetic acid bisanhydride and ethylenediamine.