Cinnamoyl backbone

Detailed spectroscopic analysis of lyconesidine C (55) revealed that 55 had a similar backbone skeleton to that of lycodoline. The presence of an acetoxy at C-6 and a 3,4-dimethoxy cinnamoyl ester at C-5 was revealed by the HMBC correlations of H-6 and H3-I8 to C-17, and H-5 and H-20 to C-19. The relative stereochemistry of 55 was deduced from NOESY correlations. 

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