ChemInform Abstract: Structure Revision and Internal Acyl Migration of Gymnemarsgenin

Reinvestigation of the NMR spectra of gymnemarsgenin by the selective INEPT and various two-dimensional NMR techniques (DQF-COSY, ROESY, HETCOR) led to the structural revision of gymnemarsgenin as 12 β - O -cinnamoyl-20- O -benzoyl sarcostin. The 1 H and 13 C NMR spectra were completely assigned. It is apparent that the 12-cinnamoyl group migrated to C-20 under the mild alkaline conditions rendered for partial saponification.