One-pot synthesis of a piperidine-based rigidified DTPA analogue and its bifunctional chelating agent

The core structure of cis-3,5-diaminopiperidine was N-alkylated with excess t-butylbromoacetate in order to exploit the successive N-quaternarization and Stevens rearrangement to access the pentaalkylated product and the bifunctional chelating agent containing a N-butanedioic acid pendant arm at the same time. The relaxometric properties of the Gd ^III complexes with these ligands were studied also in terms of pH and serum stabilities.