Study of the Reaction of Bis- and Tris-pyrylium and -thiopyrylium Cations with Methoxide Ion. Electronic Effects of the Heterocyclic Rings as Substituents
5-pentanediones 6 and 8. Their reaction with CD3ONa in CD3OD was studied by 1H NMR at −40 °C and at +25 °C. At low temperature, kinetically controlled mixtures of 2H and/or 4H adducts were detected, whereas at room temperature the mixtures equilibrated to yield, in all of the cases, the more stable 2H adducts exclusively. A spectrophotometric study of the reactions with sodium methoxide in methanol was carried