Synthesis of new semi-rigid chelating agents for samarium-153

This study describes a simple, efficient synthesis pathway from trans-1,2-diaminocyclohexane that provides access to a new class of semi-rigid polyamine, polycarboxylic, and polyphosphonic ligands. The key steps in synthesis were the functionalisation (with an appropriate branching group) of a bisphosphonate diaminocyclohexane derivative and the introduction of methanephosphonic functions by a rarely used method.