Synthesis of bicyclo[2.2.2]oct-5-en-2-ones via a tandem intermolecular Michael addition intramolecular aldol process (a bridged Robinson annulation)

Bicyclo[2.2.2]oct-5-en-2-ones 19 can be made in a one-pot process from ketones 18 and cyclohexenone 6 in strong acid.