Green-Light-Induced Cyclopropanation of Alkenes via Cooperative NHN/Ligated Boryl Radical Activation of Dichloromethane

Ligated boryl radicals (LBRs), generated from Lewis base-coordinated boranes, have emerged as powerful tools capable of halogen-atom transfer (XAT) processes. Nevertheless, metal-free LBR-enabled radical chemistry remains largely confined to radical additions or cascade pathways. Herein, we report a green-light-induced cyclopropanation of alkenes using dichloromethane (DCM) as a C1 synthon, enabled by the synergistic action of N-heterocyclic nitrenium (NHN) catalysts and LBRs. This work demonstrates a transition-metal-free cyclopropanation of alkenes with DCM, further highlighting the synthetic potential of the NHN/LBR cooperative strategy.