As a consequence of the relatively poor solubility of the nitro-derivatized compound 2-(4-nitrobenzyl-3,6,9,12-tetraoxo-1,4,7,10-tetraazacyclododecane, alternative intermediates may be employed in the synthesis of nitrobenzyl-DOTA. For example, the nitro group may be substituted by hydrogen or RNH- where R is an amino protecting group.