In theory, yes. Density functional theory (DFT) calculations were used to explore the possibility that 7-diazo-cycloheptatriene compounds might undergo an intramolecular cyclopropanation to substituted semibullvalenes. Our computational study reveals that, in theory, it is possible to do so, though side reaction pathways explored suggest that beta-hydride elimination to heptafulvenes may pose a challenge to realizing an efficient synthesis to semibullvalenes. The cycloheptatriene - norcaradiene equilibrium was also considered. Effects of various substituents informed our design to mitigate side reactions. Finally, we compared our theoretical explorations toward semibullvalenes to a closely-related, and synthetically relevant, Au(I) catalyzed 6-endo-dig cyclization of 7-ethynyl-1,3,5-cycloheptatrienes to barbaralones reported by Ferrer and Echavarren. We hope our theoretical study might inspire a synthesis of semibullvalene using this method.

Can dirhodium complexes catalyze cyclopropanation of cycloheptatriene diazo compounds to synthesize substituted-semibullvalenes?

ACS Spring 2022

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