Photoredox Activation of Donor‐Acceptor Cyclopropanes: Distonic Radical Cation Reactivity in [3+2] Cycloaddition Reactions

Altering the reactivity model of a molecule can potentially eliminate limitations existing in its current paradigm. When it comes to the activation of Donor‐Acceptor Cyclopropanes (DACs), Lewis acids have been the state‐of‐the‐art. Although a variety of polarized 2π components have been successfully coupled with DACs for [3+2] cycloaddition, unpolarized alkenes prove to be a roadblock due to an inherent polarity mismatch with the Lewis acid‐mediated 1,3‐zwitterionic intermediate. Hereby, harnessing the distonic radical cation mode of cleavage by photoredox catalysis overcomes this mismatched reactivity of the zwitterionic intermediate, providing a unique route to highly substituted cyclopentanes and cyclopentenes. Expansion of this strategy to bicyclo[1.1.0]butanes enables access to bicyclo[3.1.1]heptanes (BCHs) through a facile [3σ+2σ] cycloaddition. Detailed mechanistic insights are also provided using dispersion‐corrected density functional theory.