二维接力-HOHAHA和NOE差谱法测定甙类化合物的结构

该文提出一种新的二维接力-HOHAHA实验方法.研究结果表明,该方法可用于从高度重迭的谱图中分离出各个糖体的¹H NMR信号,并且与NOE差谱实验相结合可以用于测定甙类化合物中糖体间和糖体与甙元间的连接位置.本方法以¹H NMR为基础,故其灵敏度比以¹³C NMR为基础的甙化位移方法高得多.

THE STRUCTURE DETERMINATION OF GLYCOSIDE BY TWO-DIMENSIONAL RELAY-HOHAHA AND DIFFERENCE NOE EXPERIMENTS

A new NMR technique, two-dimensional RELAY-HOHAHA NMR spectroscopy was developed. The results obtained showed that the efficiency of magnetization transfer among sugar residues of glycoside are much better for this method than that for 2D RELAY COSY and 2D HOHAHA experiments. The subspectra corresponding to individual sugar components were extracted even from overlapping proton resonance by taking the cross sections of 2D spectra para-llel to the F2 axis at anomeric proton resonance. Thus all the sugar proton resonances can be assigned to the individual sugar components. 2D RELAY-HOHAHA experiment in combination with NOE difference spectroscopy has been successfully used for determining the glycosidation position in an aglycome moiety and the sequence of sugar moiety in a natural glycoside without chemical degradation. The sensitivity for the present procedure based on proton NMR is much better than that for glycosidation shift based on 13C NMR.