Synthesis of (-)-Picrotoxinin by Late-Stage Strong Bond Activation.

We report a concise, stereocontrolled synthesis of the neurotoxic sesquiterpenoid (-)-picrotoxinin (1, PXN). The brevity of the route is due to regio- and stereoselective formation of the [4.3.0] bicyclic core by incorporation of a symmetrizing geminal dimethyl group at C5. Dimethylation then enables selective C-O bond formation in multiple intermediates. A series of strong bond (C-C and C-H) cleavages convert the C5 gem-dimethyl group to the C15 lactone of PXN.

Picrotoxin-like lactones.

Preparation of some simple lactone analogues of picrotoxin and their biological evaluation is reported. Certain analogues possessed activity, but at potencies insufficient to warrant further work.