of derivatives of cyclohexane, piperidine, and thian in chair and twist eonformers, and of model compounds, lead to estimates of deshielding (Δδ = 3.6 ± 0.2 ppm) for axial CMe3 on a cyclohexane ring and shielding (Δδ = −0.2 to −0.6 ppm) for ψe-CMe3 in twist conformers, relative to equatorial CMe3. Ring carbon atoms are considerably shielded in twist conformers relative to chair eonformers. The value
椅子和扭曲形成物中
环己烷,
哌啶和
硫杂的衍
生物以及模型化合物的13 C NMR光谱导致对
环己烷环上轴向
CME 3的去屏蔽作用(Δδ= 3.6±0.2 ppm)和屏蔽作用(Δδ= -0.2至-0.6 ppm的)为方位角Ψe-
CME 3在捻构象,相对于赤道
CME 3。相对于椅子构形者,环碳原子在扭曲构象异构体中被显着屏蔽。在椅子扭扭平衡研究中13 C
化学位移的值通过对化合物的非对映异构体对(11和13;38和50)进行可变温度测量来举例说明。