Macrocyclic structures containing nitrogen atoms are widespread in nature. Indeed, polyazamacrocycles play fundamental role in biological processes as illustrated when considering porphyrins or related compounds. The study of polyazamacrocycles involves joint research from both organic synthetic and inorganic or organometallic chemists but, importantly, the utility of these ligands falls far beyond chemistry. For instance, polyazamacrocycles and their complexes have been extensively used in catalysis but have found an irreplaceable place in the field of medicine as therapeutic or diagnosis agents, as well as biological sensors.

With virtually countless imaginable possibilities, there are several macrocyclic architectures that are ubiquitous. Among them, tetraaza-12-membered macrocycles, in which at least one of the N-atoms belongs to a pyridine ring, holds a privileged position. This fact could be attributed to the particular properties conferred to the macrocyclic ligand by the presence of the pyridine(s) ring(s) which are, subsequently transferred to the complex when coordinated. At first, the introduction of the pyridine ring allows a fast coordination due to the rigidity imposed by the pyridine ring. The corresponding complexes normally showed an increased thermodynamic and kinetic stability. We are interested in expanding the synthetic paths available for the synthesis of 12-membered macrocycles derived from pyclen (pyclen = 3,6,9-triaza-1(2,6)-pyridinacyclodecaphane).