Metallocarbenes as Substituents in 8‐Electron Electrocyclizations

Density functional theory was used to elucidate the mechanism and the pericyclicity of chromium‐catalyzed bicyclization reactions that purportedly involve 8‐electron electrocyclization steps. Our computational results indicate that these reactions do indeed proceed via 8‐electron electrocyclization rather than an alternative pathway involving 4‐electron electrocyclization followed by Cope rearrangement. The role of C=[M] groups on the electrocyclization, specifically its pericyclicity, was examined in detail using modern theoretical tools. The mechanism and the pericyclicity of metal‐promoted bicyclization reactions that purportedly involve 8‐electron electrocyclization steps were examined computationally, with results showing that these reactions do indeed proceed via 8‐electron electrocyclizations rather than alternative pathways involving 4‐electron electrocyclizations followed by Cope rearrangements.