Depsides galloyl esters

Fig. 4. Chemical shift of aryl carbon atoms of depside galloyl esters...

Using NMR the formation of the additional m-depside linkages was shown to occur preferentially to those galloyl ester groups attached to C-2 or C-3, C-4 and C-6 of the D-glucopyranose (Fig. 15). 

Spectroscopic measurements combined with the use of the methanolysis reaction have provided evidence for the occurrence of the complex ester in other plants. The chemical shift of the aromatic protons of depsidically linked galloyl ester groups occurs downfield from those of simple aliphatic galloyl esters (de acetone or de DMSO, 8 values from TMS, depside 7.25 — 7.70, simple ester 6.9—7.20). It is possible using this measurement to estimate the average value of the number n for the ester isolated from a particular plant. Methanolysis followed by a quantitative hplc analysis of the products (11) and (12) confirms the nature of this analysis. 

The presence of depsidically linked galloyl ester groups in (18) is also indicated by nmr and by mass spectrometry. In the nmr... 

Galloyl esters of D-glucose Depside Metabolites ----------p-Penta-o-galloyl-D-glucose... 

---