Post-synthetic isotopic labeling of an azamacrocyclic ligand

A simple post-synthetic method for the preparation of 1,4,7-triazacyclononane-d12 (90% atom D) is reported. The macrocycle is first converted into 1,4,7-trinitroso-1,4,7-triazacyclononane, whose solid-state and solution properties are herein described. In CD3OD/D2O solution, the trinitroso derivative undergoes fast base-catalyzed H/D exchange on the whole set of methylene hydrogens and can be subsequently denitrosated by reduction with Ni/Al alloy.