Internuclear cyclisation. Part XXVIII. Free radical reactions of some spirocyclohexadiene lactams

Abstraction of hydrogen from the spirocyclohexadiene lactam (1) and related compounds gives cyclohexadienyl radicals, at low temperatures (60°), dimerise; at higher temperatures rearrangement may give N-alkylphenanthridinones; the effect of substituents in the cyclohexadiene ring on the case of this rearrangement is considered. The abstraction of hydrogen from the cyclohexadienyl radical dimers leads to dehydrodimers; the nature of these is also temperature dependent.