Generation of Bicycloheptatrienes

Article abstract of DOI:10.1021/jo00320a019

Derivatives of bicyclo<4.1.0>heptatriene have been generated in solution by the base-induced dehydrochlorination of gem-dichlorocyclopropanes.Reaction of 7,7-dichlorodibenzobicyclo<4.1.0>heptane with potassium tert-butoxide in tetrahydrofuran at 0 deg C gives mainly products derived from solvent incorporation by carbene insertion.Evidence that the carbene results from rearrangement of the bicycloheptatriene derives from the successful interception of the bicycloheptatriene with nucleophile (MeS^-). endo-7-Chlorodibenzobicyclo<4.1.0>heptane failed to reactwith potassium tert-butoxide in tetrahydrofuran.Generation of benzobicyclo<4.1.0>heptatrienes was also accomplished via the base-induced dehydrochlorination of gem-dichlorocyclopropanes. 1-Methylbenzobicyclo<4.1.0>heptatriene gives products derived from multiple carbene-carbene rearrangements.In contrast, nonannelated methylbicycloheptatrienes generated by the dehydrochlorination route give only carbene-derived products resulting from the initially produced bicycloheptatriene.