Radical cyclisations of various methylenecyclopropane derivatives have been studied. Cyclisation of diphenylsubstituted (methylenecyclopropyl) butyl radical 10 gave the unexpected cyclohexene 5, via a series of radical rearrangements. In further studies,( methylenecyclopropyl) radicals underwent exclusive 5-exo cyclisation, while (methylenecyclopropyl) butyl radicals gave mixtures of products resulting from 6-exo and ...