LR-HSQMBC: A Sensitive NMR Technique To Probe Very Long-Range Heteronuclear Coupling Pathways
LR-HSQMBC: A Sensitive NMR Technique To Probe Very Long-Range Heteronuclear Coupling Pathways
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DOI：
10.1021/jo500333u
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发表时间：
2014-05-02
影响因子：
3.6
通讯作者：
Parella, Teodor
中科院分区：
文献类型：
--
作者：
Williamson, R. Thomas;Buevich, Alexei V.;Parella, Teodor
HMBC是有机和无机分子结构解析中最常用和最重要的NMR实验之一。我们已经开发了一种新的，高灵敏度的NMR脉冲序列，克服了典型的（2，3）j（CH）的HMBC的限制，通过扩展远程相关数据的可视化4-，5-，甚至6键远程（n）J（CH）杂原子耦合。这项技术应该被证明是一个有效的实验，以补充HMBC探测质子缺陷分子的结构。LR-HSQMBC NMR实验实际上可以扩展HMBC的范围，即使在样品有限的情况下也能提供与1，n-ADEQUATE相似的数据。这是通过优化响应非常小的（n）J（CH）coupings，而不是依赖于显着较低的灵敏度检测远距离耦合的C-13-C-13 homoblasts对在自然丰度。DFT计算用于确定在计算的长程偶联的基础上观察到的对赛维霉素A（2）的甚长程相关性是否合理。
HMBC is one of the most often used and vital NMR experiments for the structure elucidation of organic and inorganic molecules. We have developed a new, high sensitivity NMR pulse sequence that overcomes the typical (2,3)j(CH) limitation of HMBC by extending the visualization of long-range correlation data to 4-, 5-, and even 6-bond long-range (n)J(CH) heteronuclear couplings. This technique should prove to be an effective experiment to complement HMBC for probing the structure of proton-deficient molecules. The LR-HSQMBC NMR experiment can, in effect, extend the range of HMBC to provide data similar to that afforded by 1,n-ADEQUATE even in sample-limited situations. This is accomplished by optimizing responses for very small (n)J(CH) coupings as opposed to relying on the markedly less sensitive detection of long-range coupled C-13-C-13 homonuclear pairs at natural abundance. DFT calculations were employed to determine whether the very long-range correlations observed for cervinomycin A(2) were reasonable on the basis of the calculated long-range couplings.