is doubly protonated at the exocyclic oxygen atom. The sulphur and nitrogen analogues, 2,6-dimethyl-4H-thiopyran-4-one, and 2,6-dimethyl-N-methyl-4-pyridone, respectively, behave similarly. Other related compounds show 1H and 13C n.m.r. spectra in support of our interpretation.
1 H和13 C nmr光谱表明,在HSO 3 F–SbF 5(1:1)溶液中的2,6-二甲基-4 H-
吡喃-4-酮在环外氧原子处被双质子化。
硫和氮类似物,分别为2,6-二甲基-4 H-
噻喃-4-酮和2,6-二甲基-N-甲基-4-
吡啶酮。其他相关化合物显示1 H和13 C nmr光谱以支持我们的解释。