Two-directional synthesis. Part 1: A short formal synthesis of (±)-histrionicotoxin and (±)-histrionicotoxin 235A

The formal synthesis of (±)-histrionicotoxin and (±)-histrionicotoxin 235A using a two-directional strategy has been accomplished. The key feature of the synthesis is a tandem oxime formation/Michael addition/nitrone cycloaddition sequence, which form the azaspiro[5.5]undecane skeleton in two operations from an acyclic symmetrical precursor.