described. The barriers to rotation of the naphthyl groups were probed by MM2 and by dynamic 1H-NMR spectroscopy. An achiral syn and a chiral anti conformation were experimentally observed at −90°C for the free ligands and at −40°C for the complexes. The experimental ΔG≠ and the calculated ΔH≠ values are in fair agreement. The barriers are substantially higher in the alkali metal complexes than in the
描述了从α-
萘酚(3)开始的在双键处具有邻位α-
萘基的2,3-二氢[15] crown-5和-[18] cro-6衍
生物4a,b的合成。MM2和动态1 H-NMR光谱探测了
萘基旋转的障碍。在-90°C时对游离
配体在-40°C时观察到非手性顺式和手性反构象,在-40°C时观察到复合物。实验的ΔG ≠和计算出的ΔH ≠值基本一致。碱
金属配合物中的阻挡层比游离
配体中的阻挡层高得多。在外消旋和
钾S存在下通过低温1 H-NMR光谱观察到具有(4b)的-(+)-
扁桃酸盐非平衡离子对的反构象。