Treatment of a variety of substituted vinylcyclopropyl selenyl esters, eg 11, with Bu3SnH– AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50–60% yield. By contrast, treatment of conjugated triene selenyl esters, eg 32, with Bu3SnH–AIBN produces substituted 2- ...