Sulfonylisothiocyanates 1 and β,β-dimethylenamines 2 react to yield the dipoles 3. In nonpolar solvents an equilibrium exists between 3 and the thietanes 4. The free activation enthalpy for the ring closure 3→4 was obtained from the temperature dependent NMR spectra in liquid sulfur dioxide. Protonation of 3 with perchloric acid leads to the salts 8 which, as indicated by ΔG≠-values obtained from NMR
磺酰基异
硫氰酸酯1和β,β-二甲基
亚胺2反应生成偶极3。在非极性溶剂中,在3和
硫杂
环丁烷4之间存在平衡。从液态
二氧化硫中依赖于温度的NMR光谱获得了3→4闭环的自由活化焓。用
高氯酸使3质子化,得到盐8,如由NMR谱获得的ΔG ≠值所示,该盐也能闭环。