The peptide way to macrocyclic bifunctional chelating agents: synthesis of 2-(p-nitrobenzyl)-1,4,7,10-tetraazacyclododecane-N,N',N",N'''-tetraacetic acid and study of its yttrium(III) complex
J Am Chem Soc. 1988 Aug 1;110(18):6266-7.
doi: 10.1021/ja00226a063.