Synthesis of macrocyclic bifunctional chelating agents: 1,4,7-tris(carboxymethyl)-10-(2-aminoethyl)-1,4,7,10-tetraazacyclododecane and 1,4,8-tris(carboxymethyl)-11-(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane

Abstract

The convenient, synthetically useful bifunctional chelating agents, 1,4,7-tris(carboxymethyl)-10-(2-aminoethyl)-1,4,7,10-tetraazacyclododecane and 1,4,8-tris(carboxymethyl)-11-(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane, were obtained by reaction of ethyl bromoacetate with 1,4,7,10-tetraazacyclododecane and 1,4,8,11-tetraazacyclotetradecane, followed by reaction with N-(2-bromoethyl)phthalimide. This method is proven to be more efficient to prepare bifunctional chelating agents with aliphatic side arms in high yields, above 53%.