3 -Methylevernic acid

Until recently only two mixed orcinol P-orcinol depsides were known, namely obtusatic acid (210) and norobtusatic acid (211), but now a further four such compounds have been reported. These include 2-0-methylobtusatic acid (212) present in Xanthoparmelia tucsonensis 45) and evernine (213) 253), 3 -methylevernic acid (214) 252) and methyl 3 -methyllecanorate (215) 252) all obtained from Evernia prunastri. 

The spectral properties of depsides, in particular H-n.m.r. and mass spectra, provide a powerful probe in structural elucidation. C-n.m.r. spectroscopy has recently been used in the structural elucidation of ovoic acid (235) 194), 2",4-di-0-methylgyrophoric acid (236) (252), evernine (213) (255), 3 -methylevernic acid (214) (252) and methyl 3 -methyl-ecanorate (215) (252) but following a generalised study this technique 311, 312) will undoubtedly prove to be particularly important in the future. 

Methylevernic acid OH H OMe H Me Me OH CO2H Me H Evernia prunastri Column chromatography Spectral data ( C- 252) n.m.r.), synthesis... 

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