Stereochemical determination of NMR chemical shifts in marine terpenoids, antheliol and sangiangol B, using DFT calculations

Stereochemical determination of flexible, trinor-guaiane sesquiterpenoids, antheliol (1a) and sangiagol B (2a), isolated from a marine soft coral, Anthelia sp., was supported by quantum chemical calculations of NMR chemical shifts at DFT levels. The relative configuration of antheliol is now revealed, as 1S*, 4S*, 7S*, 10R* as in 1b, whereas sangiangol B (2c) has complete stereochemistry as 1S*, 7R*, 8R*, 10R*, 11R*, 12S*.