Intramolecular hydroxylamine-alkyne cyclisation of the hydroxylamines 8 and 9 afforded six- membered cyclic nitrones which without isolation underwent a tandem intramolecular dipolar cycloaddition to produce the tricyclic isoxazolidines 6 and 7 respectively. These were converted in two steps into the ladybird defence alkaloids (±)-euphococcinine 4 and (±)- adaline 5.
