Attempted Synthesis of Calicene from Trisubstitued Cyclopropanes and CyclopentenoneThe Li carbenoids4, prepared by treatment of substituted 1,1‐dihalocyclopropanes with BuLi, are reacted with cyclopent‐2‐enone under thermodynamic and kinetic control (Scheme 1). In general, the latter procedure gives better yields of cyclopropylcyclopentenols5a–e, but the reaction seems to be controlled mainly by the steric and electronic properties of the substituent Y. So, with4band4e, the main reaction is the attack of the carbenoid at C(1) of cyclopent‐2‐enone, while4a(Y = PhS) predominantly deprotonates the ketone (Scheme 4). Whereas5dand5ecan easily be converted to the dihydrocalicenes6dand6e(Scheme 6), the attempted elimination of H2O from5a–cleads to the rearranged products13–2due to the opening of the cyclopropane ring (Scheme 5). Finally, the generation of the parent compound2from the silylated precursor6dis attempted: treatment with MeO−gives the addition products18A/18B, while the reaction with Br2provides19by a bromination/dehydrobromination se