Novel furan-, thiophene- and benzo[b]thiophene bridged macrocycles of 4,4 '-bipyridine

Eight novel heterocyclic bridged phanes of the paraquat type were synthesiz ed by a simple two-step procedure. Starting from furan bridged bis(4,4 '-bi pyridinium) dication 2 and the corresponding bis(bromomethyl)arenes furanop hanes of 4,4 '-bipyridine were obtained in moderate to high yields. In simi lar manner thiophenophane 9 was synthesized in low yield using dication 8 a s precursor. The spectroscopic properties of furanophane 4 and thiophenopha ne 9 were compared. Cycloadditions on the furan ring failed, which is attri buted to the decrease of electron density of the furan ring caused by neigh bouring electron-accepting bipyridinium groups. The syntheses of the benzo[ b]thiophene bridged phanes were performed starting from dibromide 10 and bi s(4,4 '-bipyridinium) dications 12-14 since the instability of the required bis(4,4 '-bipyridinium) dication 11 did not allow its use in aqueous solut ion. (C) 1999 Elsevier Science Ltd. All rights reserved.