Nucleophilic alkylation of gem-dichlorocyclobutenones with alkyl-organometallics is relatively challenging in accessing C(sp3)-enriched α-chlorocyclobutenones. Leveraging single-electron oxidation ability, herein, we report readily accessible alkyltrifluoroborates, enabling a photoinduced SOMOphilic allylic alkylation of gem-dichlorocyclobutenones under metal-free conditions. Additionally, alkene feedstocks are exploited as latent C(sp3) partners in this C(sp3)-C(sp3) bond-forming transformation. This reaction proceeds with high fidelity, expanding the previously limited scope of β-alkyl cyclobutenones beyond β-aryl analogues and enabling access to pharmaceutically relevant scaffolds. Conceptual DFT calculations rationalize the preferential α-radical addition over β-addition, alongside other experimental supports, including an EPR study, for the SET-mediated mechanism.
Beck et al. (Mon,) studied this question.