Pd-catalyzed amination of 2,6-dihalopyridines with polyamines

The Pd-catalyzed amination of 2,6-dibromopyridine with various linear polyamines and oxapolyamines was studied. In this way polyazamacrocycles 3 containing one pyridine and one polyamine moiety were synthesized using equimolar amounts of starting compounds. Two alternative approaches were elaborated and compared for synthesis of macrocycles 11 comprising two pyridine and two polyamine fragments: via intermediate formation of N^α,N^ω-bis(6-halopyridin-2-yl)polyamines 7, 8 or via 2,6-bis(polyamino)-substituted pyridines 10. A series of N-(6-tert-butoxypyridin-2-yl)-substituted polyamines 12 and N^α,N^ωbis(6-tert-butoxypyridin-2-yl)-substituted polyamines 13 were obtained by similar procedures, and the possibilities of N,N-dihetarylation of such compounds using 2-bromopyridine and 2-bromo-6-tert-butoxypyridine were studied. The yields of linear and cyclic products were shown to be strongly dependent on the nature of starting polyamines and of the halogen atom.