Cyclohelminthol CPs: Scope and Limitations of Density Functional Theory-Based Structural Elucidation of Natural Products
Cyclohelminthol CPs: Scope and Limitations of Density Functional Theory-Based Structural Elucidation of Natural Products
复制标题
环蠕虫醇 CP：基于密度泛函理论的天然产物结构解析的范围和局限性
DOI：
10.1021/acs.joc.0c02378
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Hashimoto M
中科院分区：
文献类型：
--
作者：
Inose K;Tanaka S;Tanaka K;Hashimoto M
用密度泛函理论（DFT）计算方法对新分离自Helminthosporium velutinumyone 96的环蠕虫醇CP-1（1）、CP-2（2）、CP-3（3）和CP-4（4）进行了结构测定，证明了DFT计算方法在复杂和构象灵活的天然产物结构测定中的有效性和局限性。在DFT计算之前，使用常规的光谱分析对结构进行了初步归属。参考DFT-衍生的13 C和1H NMR化学位移，3 JHHandnJCH值和电子圆二色性（ECD）光谱，结构进行了验证。13 C化学位移计算对于验证环结构部分是非常有效的，但是对于验证其中接合不对称碳（C-16）与环结构部分分开的侧链的几何结构不太有效。然而，1H化学位移计算补偿了后者的不完善。ECD光谱计算用于确定绝对构型。虚拟简单模型分子的计算，使我们能够评估的ECD光谱计算的可靠性，并得出负责的特征棉花效应的手征扭转。
The effectiveness and limitations of density functional theory (DFT) calculations in the structural determination of complexed and conformationally flexible natural products were demonstrated using the cyclohelminthols CP-1 (1) CP-2 (2), CP-3 (3), and CP-4 (4) newly isolated fromHelminthosporium velutinumyone96. Prior to DFT calculations, the structures were tentatively assigned using conventional spectroscopic analyses. The structures were verified with reference to DFT-derived13C and1H NMR chemical shifts,3JHHandnJCHvalues, and electronic circular dichroism (ECD) spectra. The13C chemical shift calculations were very effective for verifying the ring-structure moieties but less effective for verifying the geometry of the side chain in which the juncture asymmetric carbon (C-16) was apart from the ring-structure moiety. However,1H chemical shift calculations compensated for the imperfection of the latter. ECD spectral calculations were used to determine the absolute configurations. Calculations for virtual simple model molecules enabled us to evaluate the reliability of the ECD spectral calculation and derive the chiral torsion responsible for the characteristic Cotton effects.