Universal NMR databases for contiguous polyols
Universal NMR databases for contiguous polyols
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DOI：
10.1021/ja0375481
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发表时间：
2003-11-26
影响因子：
15
通讯作者：
Kishi, Y
中科院分区：
文献类型：
--
作者：
Higashibayashi, S;Czechtizky, W;Kishi, Y
基于 1,2,3-三醇 1asimilar tod、1,2,3,4-四醇 2asimilar toh 和 1,2,3,4,5-五醇 3asimilar top，NMR 数据库具有四种类型的剖面描述符（C-13-、H-1- 和 H-1(OH)-化学位移和邻位自旋耦合常数）报道了连续的多元醇。为了系统地评估这些数据库的相对价值，对七醇 4a 类似 tod 进行了案例研究，通过该案例研究，伽马效应和δ效应已被认识到可以通过应用独立性质概念来完善预测的 C-13 和 H-1 化学位移曲线。伽马效应和δ效应的大小取决于存在于独立盒内部和外部的官能团的特定立体化学排列，并且仅对于属于特定子组的立体异构体有意义。除了属于特定子组的官能团的立体化学排列之外，对于未知化合物的立体化学分析，在一级近似下可以忽略伽玛效应和δ效应。对于属于特定子组的立体异构体，有必要结合伽玛效应和δ效应来细化在一阶近似下预测的分布。使用类似于 tod 的庚醇 4，评估了 (3)J(H,H) 曲线的值。已经开发了两种方法，一种使用由三个连续 (3)J(H,H) 常数组成的分布图，另一种使用由两个连续 (3)J(H,H) 常数组成的分布图。基于三个或两个连续 (3)J(H,H) 图谱的立体化学分析在操作上比基于 C-13 和 H-1 化学位移图谱的立体化学分析更简单。因此，建议使用 (3)J(H,H) 谱作为主要装置来预测未知多元醇的立体化学，并使用 C-13 和 H-1 化学位移谱作为辅助装置来确认预测的立体化学。
On the basis of 1,2,3-triols 1asimilar tod, 1,2,3,4-tetraols 2asimilar toh, and 1,2,3,4,5-pentaols 3asimilar top, NMR databases with four types of profile-descriptors (C-13-, H-1-, and H-1(OH)-chemical shifts and vicinal spin-coupling constants) for contiguous polyols are reported. To systematically assess the relative values of these databases, a case study has been conducted on heptaols 4asimilar tod, through which the gamma- and delta-effects have been recognized to refine the C-13 and H-1 chemical shift profile predicted via an application of the concept of self-contained nature. The magnitudes of gamma- and delta-effects depend on a specific stereochemical arrangement of the functional groups present in both the inside and outside of a self-contained box and are significant only for the stereoisomers belonging to a specific sub-group. With the exception of the stereochemical arrangement of functional groups belonging to a specific sub-group, the gamma- and delta-effects can, at the first order of approximation, be ignored for the stereochemical analysis of unknown compounds. For the stereoisomers belonging to a specific sub-group, it is necessary to refine, with incorporation of the gamma- and delta-effects, the profile predicted at the first order of approximation. With use of heptaols 4asimilar tod, the values of (3)J(H,H) profiles have been assessed. Two methods, one using profiles consisting of three contiguous (3)J(H,H) constants and the other using profiles consisting of two contiguous (3)J(H,H) constants, have been developed. A stereochemical analysis based on three, or two, contiguous (3)J(H,H) profiles is operationally simpler than one based on C-13 and H-1 chemical shift profiles. Therefore, it is recommended to use a (3)J(H,H) profile as the primary device to predict the stereochemistry of unknown polyols and C-13 and H-1 chemical shift profiles as the secondary devices to confirm the predicted stereochemistry.