Synthesis and characterisation of medium-sized ring systems by oxidative cleavage. Part 2: Insights from the study of ring expanded analogues
作者:Tomas Lebl、Magali M. Lorion、Alan M. Jones、Douglas Philp、Nicholas J. Westwood
DOI:10.1016/j.tet.2010.10.043
日期:2010.12
Variable temperature NMR analysis and computational methods have been used to develop a detailed understanding of the 1H NMR spectra of a family of medium-sized ring containing compounds. The family consists of analogues containing 10-, 11- and 12-membered rings and in all cases the NMR spectra at room temperature showed a series of diastereotopic methylene signals despite the lack of a stereogenic
可变温度NMR分析和计算方法已用于对1一族中等大小的含环化合物的1 H NMR光谱。该家族由含有10元,11元和12元环的类似物组成,尽管在这些系统中缺少立体异构中心,但在所有情况下,室温下的NMR谱图均显示出一系列非对位亚甲基信号。在较高温度下重复NMR分析时,对于12元环系统,所有信号均会合并,与环构象异构体的完全相互转化一致。这在类似的10元和11元环系统中未观察到,在NMR时标上构象体的交换仍然很慢。但是,一维gs-NOESY / EXSY NMR实验表明,在较小的环系统中,确实发生了非对映体质子的相互转化。