Deuterium Labelling to Extract Local Stereochemical Information by VCD Spectroscopy in C-D Stretching Region: A Case Study of Sugars
Deuterium Labelling to Extract Local Stereochemical Information by VCD Spectroscopy in C-D Stretching Region: A Case Study of Sugars
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通过 VCD 光谱在 C-D 拉伸区域进行氘标记提取局部立体化学信息：糖的案例研究
DOI：
10.1039/d1ob02317a
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Kenji Monde
中科院分区：
文献类型：
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作者：
Mohamad Zarif Mohd Zubir;Nurul Fajry Maulida;Yoshihiro Abe;Yuta Nakamura;Mariam Abdelrasoul;Tohru Taniguchi;Kenji Monde
具有多个手性中心的分子的立体化学解析是困难的。即使使用VCD光谱法，排除除一个以外的所有非对映异构体结构候选物也是具有挑战性的，因为许多中心中的一个手性中心的立体化学转化并不总是导致它们的VCD光谱中的显著差异。这项工作表明，在2300-1900 cm−1区域引入吸收的合适VCD发色团可用于提取局部立体化学信息，并作为案例研究用于各种糖的C-1位置的立体化学分配。通过对单糖及其衍生物的一系列差向异构体对的研究，我们发现在每个C-1位置引入一个-OCD 3基团，在2300-1900 cm−1区域产生几乎镜像的VCD图案，这取决于C-1的立体化学，而与其他分子部分无关。这项工作还表明，所观察到的VCD信号和计算的比较，使在附近的发色团的手性中心的立体化学分配。这项研究提供了一个概念证明，即使用VCD发色团在2300-1900 cm−1区域，使合适的分子系统的选择的立体化学分析。对这一概念的进一步研究，应导致发展的方法，用于其他类型的复杂分子的结构说明。
Stereochemical elucidation of molecules with multiple chiral centers is difficult. Even with VCD spectroscopy, excluding all but one diastereomeric structural candidate is challenging because the stereochemical inversion of one chiral center among many centers does not always result in noticeable differences in their VCD spectra. This work demonstrates that the introduction of a suitable VCD chromophore with absorption in the 2300–1900 cm−1 region can be used for extracting local stereochemical information and for the stereochemical assignment of the C-1 position of various sugars as a case study. Through studies on a series of epimeric pairs of monosaccharides and their derivatives, we found that the introduction of one –OCD3 group to each C-1 position produced almost mirror-image VCD patterns in the 2300–1900 cm−1 region depending on the C-1 stereochemistry irrespective of the other molecular moieties. This work also shows that comparison of the observed VCD signals and the calculated ones enables the stereochemical assignment of a chiral center in the vicinity of the chromophore. This study provides a proof of concept that the use of a VCD chromophore in the 2300–1900 cm−1 region enables the analysis of selected stereochemistry of suitable molecular systems. Further studies on this concept should lead to the development of a method useful for the structural elucidation of other types of complex molecules.