Rotenoid synthesis via radical cyclisation

The (±)-6aα, 12aα, 12α-chromanochromanol acetate (11; R = Ac), representing the core structure of the insecticidal rotenoid alcohol (2), has been synthesised in six steps from the chromone (4); the cis,cis-stereochemistry is obtained in an intramolecular 6-exo aryl radical addition.