Haloaldehyde polymers, 34. 1H and 13C NMR spectra of chloral oligomers prepared by lithium tert‐butoxide initiation and the assignment of the meso/racemo addition products of the dimers
Haloaldehyde polymers, 34. 1H and 13C NMR spectra of chloral oligomers prepared by lithium tert‐butoxide initiation and the assignment of the meso/racemo addition products of the dimers
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卤醛聚合物，叔丁醇锂引发制备的三氯乙醛低聚物的 34. 1H 和 13C NMR 谱以及二聚体内消旋/外消旋加成产物的归属
DOI：
10.1002/macp.1989.021900922
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
O. Vogl
中科院分区：
文献类型：
--
作者：
K. Hatada;K. Ute;T. Nakano;F. Vašš;O. Vogl
详细研究了叔丁醇锂引发制备的氯醛齐聚物混合物的~ 1H和~（13）C NMR谱。通过13 C-1H COSY光谱和具有低功率选择性1H-去偶的13 C NMR光谱，明确地归属了二聚体级分的内消旋和外消旋非对映异构体的1H和13 C NMR信号。的二维NOESY光谱显示的信号之间的相关峰，由于次甲基（缩醛）质子的相邻的三聚体和四聚体馏分中最丰富的异构体的氯醛单体单元。测量了二聚体的1H NOE增强和3 JCH耦合常数;结果证实了基于早期构象分析的内消旋/外消旋分配。
1H and 13C NMR spectra of the mixture of chloral oligomers prepared by initiation with lithium tert-butoxide were examined in detail. 1H and 13C NMR signals due to meso and racemo diastereomers of the dimer fraction were unequivocally assigned through the 13C-1H COSY spectrum and the 13C NMR spectra with low-power selective 1H-decoupling. The two-dimensional NOESY spectrum showed correlation peaks between the signals due to the methine (acetal) protons of the neighbouring chloral monomeric units of the most abundant isomers in the trimer and tetramer fractions. The 1H NOE enhancements and 3JCH coupling constants were measured for the dimers; the results confirmed the meso/racemo assignments based on earlier conformational analysis.