The base-catalyzed rearrangement reactions of 2-bromomethylenebenzonorbornene8and 2,2-dibromomethylenebenzonorbornene9were studied. Reaction of8with potassiumtert-butoxide in THF gave only the enol ether11whose formation is rationalized via a carbene-cycloalkyne mechanism. However, treatment of9with phenyllithium in THF at −40°C gave the ringenlarged dibromide13whose structure is reported herein. The ring-enlarged product13is rationalized in terms of carbanionic rearrangement. Quantum mechanical calculations are consistent with these observatio
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