二苯并环辛二烯构象动力学规则
Rules for Dibenzocyclooctadiene Conformational Dynamics.
摘要(中文译文)
柔性化合物的构象动力学可以有意义地影响它们的核磁共振光谱和生物活性，但这些影响很容易被忽视。二苯并环辛二烯木脂素就是一个明显的例子。尽管已经发表了>350种天然存在的二苯并环辛二烯，但离散的光谱特征没有被注意到，对其构象动力学的误解充斥着文献。在观察到从（kadheterins I-K，-）中分离出的一系列新的二苯并环辛二烯在几个共振处的C NMR信号展宽后，我们注意到了这一点。为了理解这一点，我们回顾了71种已发表的二苯并环辛二烯的C NMR光谱，发现>70%的化合物显示出相同的加宽，但根本原因尚未明确。系统分析表明，这种加宽与C-6上的关键苄基取代基有关。计算和VT-NMR分析表明，这些在扭曲船椅（TBC）构象中引入了不稳定的空间相互作用，促进了与不太稳定的扭曲船（TB）的交换。相比之下，发现某些取代基（例如C-7/C-8）可以稳定TBC。因此，许多之前被描述为采用离散TB/TBC构象的二苯并环辛二烯是相互转化的混合物。我们将我们的观察浓缩成一套规则，预测常见取代基如何影响这类化合物的环动力学。
Abstract
The conformational dynamics of flexible compounds can meaningfully influence their NMR spectra and biological activities, yet these effects are easily overlooked. The dibenzocyclooctadiene lignans provide a clear example of this. Although >350 naturally occurring dibenzocyclooctadienes have been published, discrete spectral features have gone unnoticed, and misconceptions about their conformational dynamics pervade the literature. Our attention was drawn to this after observing C NMR signal broadening at several resonances in a series of new dibenzocyclooctadienes isolated from , (kadheterins I-K, -). To understand this, we reviewed the C NMR spectra of 71 published dibenzocyclooctadienes and found that >70% displayed the same broadening, yet the underlying cause had not been clearly rationalized. Systematic analysis revealed that this broadening is associated with key benzylic substituents at C-6. Computational and VT-NMR analyses revealed that these introduce destabilizing steric interactions in the twist-boat chair (TBC) conformation, promoting exchange with the less stable twist-boat (TB). In contrast, certain substituents (e.g., at C-7/C-8) were found to stabilize the TBC. Therefore, many dibenzocyclooctadienes previously described as adopting discrete TB/TBC conformers are interconverting mixtures. We have condensed our observations into a set of rules that predict how common substituents affect ring dynamics in this class of compounds.
如何引用
AMA
Luke P Robertson, Wen Xu, Louisa Brieskorn, Iro Chaitoglou, Jing Guo, Runyue Huang, et al. Rules for Dibenzocyclooctadiene Conformational Dynamics.. Journal of natural products. 2026; doi:10.1021/acs.jnatprod.5c01348.
APA
Luke P Robertson, Wen Xu, Louisa Brieskorn, Iro Chaitoglou, Jing Guo, Runyue Huang, et al (2026). Rules for Dibenzocyclooctadiene Conformational Dynamics.. Journal of natural products. https://doi.org/10.1021/acs.jnatprod.5c01348
GB/T 7714
Luke P Robertson, Wen Xu, Louisa Brieskorn, Iro Chaitoglou, Jing Guo, Runyue Huang, et al. Rules for Dibenzocyclooctadiene Conformational Dynamics.[J]. Journal of natural products, 2026 doi:10.1021/acs.jnatprod.5c01348.
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