Effective assignment of positional isomers in dimeric shikonin and its analogs by ^(1)H NMR spectroscopy  

作　　者：Ling-Hao Zhao Hai-Wei Yan Jian-Shuang Jiang Xu Zhang Xiang Yuan Ya-Nan Yang Pei-Cheng Zhang 

机构地区：[1]State Key Laboratory of Bioactive Substance and Function of Natural Medicines,Institute of Materia Medica,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing 100050,China

出　　处：《Chinese Chemical Letters》2024年第5期223-226,共4页中国化学快报（英文版）

基　　金：funded by the CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-028).

摘　　要：An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and 8.0Hz.Furthermore,the ^(1)H(proton)nuclear magnetic resonance(NMR)pattern of phenolic hydroxyl protons was developed as a“diagnosis signal”to ascertain the relative location of each side chain in DMSO-d_(6) at sample concentrations of 0.022-0.034 mol/L.The chemical shift differences of 0.6ppm between OH-5' and OH-1 and between OH-8'and OH-4 are assigned to Type A and Type B,respectively.All reported ambiguous structures were corrected by this pattern.Additionally,the steric structures of isolated compounds were elucidated by quantum chemical calculations of electronic circular dichroism(ECD)spectra.

关 键 词：Arnebia euchroma Dimeric hydroxyl naphthoquinones Positional isomers ^(1)H NMR spectroscopy Chemical shift difference 

分 类 号：TQ460.1[化学工程—制药化工]