Using NMR to determine the relative stereochemistry of 7,7-diaryl-8,8′-dimethylbutan-1-ol lignans

- Syn- and anti-7,7-diaryl-8,8′-dimethylbutan-1-ol lignans were synthesized.
- Analysis of NMR data for each isomers developed descriptors for each isomer.
- Descriptors can be used to determine stereochemistry in undefined butanol lignans.

Due to their linear, freely rotatable, structure many natural 7,7-diaryl-8,8′-dimethylbutan-7′-ol lignans are reported without any stereochemical assignment. Analysis of synthetic 8,8′-dimethylbutanol lignans and analogues reveals significant differences between the NMR data of syn- and anti-isomers. This information was then used to determine the relative stereochemistry of the C-8 and C-8′ methyl groups in previously undefined natural products.