Conformational analysis of picrotoxinin by NMR, X-ray crystallography, and molecular orbital and classical potential-energy calculations

The conformation of the potent convulsant drug picrotoxinin has been studied by proton n.m.r., X-ray crystallography, molecular orbital calculations and classical calculations. The calculations reveal two alternative low-energy conformations, either of which is consistent with the n.m.r. data, and one of which is also observed crystallographically. The energy difference is sufficiently small to suggest that either conformation may be the biologically active form.