Synthesis and conformational aspects of corands incorporating pyrylium, thiopyrylium and pyridine subunits

Article abstract of DOI:10.1016/S0040-4020(01)96109-5

The pyrylium corands 1a, 1b and the thiopyrylium corands 2a, 2b, were prepared in good yields by heterocyclization of the macrocyclic 1,5-pentanediones 4a, 4b, whereas the pyridine corands 3a, 3b were obtained by reacting 1a and 1b, respectively, with ammonium acetate. NMR data and molecular mechanics calculations suggest that the heteroaromatic nuclei tend to fill the cavity of the macrorings.