ALKYL RADICAL CYCLIZATIONS OF METHYLENECYCLOPROPANE DERIVATIVES

Radical cyclisations of various methylenecyclopropane derivatives have been studied. Cyclisation of diphenylsubstituted (methylenecyclopropy l)butyl radical 10 gave the unexpected cyclohexene 5, via a series of radical rearrangements. In further studies, (methylenecyclopropyl)prop yl radicals underwent exclusive 5-exo cyclisation, while (methylenecyc lopropyl)butyl radicals gave mixtures of products resulting from 6-exo and 7-endo cyclisation. No cyclisation products were detected in atte mpted cyclisations of (methylenecyclopropyl)pentyl radicals.