Cellulose-Stabilized BiOBr Enables Light-Mediated Radical-Polar Crossover of Unactivated Alkenes to Achieve Cyclopropanes

Titelangaben

Su, Wenhao ; Hu, Jun ; Pradhan, Suman ; Rodrigues, Bruno Vinicius Manzolli ; Drichel, Andreas ; Monti, Susanna ; Barcaro, Giovanni ; Jaworski, Aleksander ; Kuśtrowski, Piotr ; Slabon, Adam ; Das, Shoubhik:
Cellulose-Stabilized BiOBr Enables Light-Mediated Radical-Polar Crossover of Unactivated Alkenes to Achieve Cyclopropanes.
In: ACS Catalysis. (20 Juli 2026) .
ISSN 2155-5435
DOI: https://doi.org/10.1021/acscatal.6c02931

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Abstract

A cellulose-stabilized BiOBr photocatalyst has been developed to enable efficient light-mediated radical-polar crossover cyclopropanation of unactivated alkenes. Embedding highly dispersed BiOBr within a renewable cellulose matrix enhances catalyst stabilization and promotes catalytic performance through combined effects involving interfacial charge transfer, matrix structure, and substrate interaction. Under light irradiation, this composite selectively activates α-bromomalonates to generate reactive radical intermediates that engage a diverse range of aliphatic, aromatic, and amide-containing alkenes, delivering cyclopropanes in up to 97% yield with broad functional-group tolerance. The method accommodates complex bioactive substrates, providing a practical approach to late-stage derivatization. Furthermore, mechanistic studies, including kinetic analysis, radical trapping, and radical-clock experiments, support a photoinduced radical-polar crossover pathway featuring α-bromomalonate activation, carbocation formation, and subsequent ring closure. This work establishes cellulose-stabilized BiOBr as an environmentally friendly, broadly applicable photocatalyst for light-driven activation of nonactivated organic molecules.