Chemistry of the shellfish toxin domoic acid : characterization of related compounds

Five new compounds related to the neurotoxin domoic acid have been characterized by spectroscopic methods. They include a diastereoisomer that occurs naturally with domoic acid in mussels and four hydrogenation products. The stereochemistry of the two epimeric tetrahydro derivatives could not be assigned on the basis of the NMR data alone because of high conformational flexibility. However, a clear-cut assignment was possible by molecular modelling in combination with the NMR data.