The behaviour of 1H-cyclopropabenzene (1) and 1H-cyclopropa[b]naphthalene (23) towards a variety of radicals results in opening of the three- membered ring to give ortho -substituted benzyl and 2-methylnaphthalene derivatives, e.g. (13) and (28), respectively. Ring expansion into the cycloheptatriene manifold by way of addition to the bridge bond and norcaradiene formation have not been observed. Analogous reactions with the methylidenecyclopropa [b] naphthalenes (33) and (34) lead to much decomposition, and provide little evidence for the C1cycloproparenyl radicals (35) and (36).
Reaction of benzene-1,4-dicarboxaldehyde with anion 6 derived from 1,1-bis(trimethylsilyl)cyclopropa[b]naphthalene 1 gives 4-(methylidene-1H-cyclopropanaphthalenyl)benzaldehyde 7 as a minor product and 1,4-bis(methylidene-1H-cyclopropanaphthalenyl)benzene 8 as the major product of the reaction. With 4-(E)-2-[4-(dimethylamino)phenyl]ethenyl}benzaldehyde 14, this same anion affords the stilbene-substituted π-extended (1-arylmethylidene)cyclopropanaphthalene 15 as a sparingly soluble orange-red powder.