Synthesis of polyazamacrocycles comprising 6,6′-diamino-2,2′- bipyridine moieties via Pd-catalyzed amination

Pd-catalyzed amination of 6,6'-dibromo-2,2'-bipyridine with a variety of di-, tri-, tetraamines and oxadiamines was carried out for the synthesis of a new class of polyazamacrocycles comprising a 6,6'-diamino-2,2'-bipyridine unit. The obtained results of the catalytic amination reaction were shown to be dramatically dependent on the nature of the amines, mainly on the length of the amine chain. The shortest propane-1,3-diamine and butane-1,4-diamine derivatives provided only cyclic dimers whereas the longest di- and trioxadiamines gave desired macrocycles in very good yields. The formation of cyclic oligomers was observed in all cases. Different reaction conditions leading to cyclic dimers were explored.