Fluorinative Rearrangement of Vinyl Diazo Compounds Enabled by a New Reactivity Mode of Cyclopropanediazonium Ions

Abstract

ABSTRACT Although selective transformations of aromatic and purely aliphatic diazonium ions are well‐established, the reactivity of the unique cyclopropanediazonium (CPD) ions remains largely unexplored owing to their intrinsic instability. Herein, we report a new reaction mode of CPD ions mediated by hypervalent iodine reagents. The reaction enables a fluorinative 1,2‐diazo function migration of vinyl diazo compounds to afford synthetically useful but previously unavailable β,β‐difluorinated diazoester products. This transformation exhibits high efficiency, broad substrate scope, facile scalability, and complete chemo‐ and regioselectivity, alongside versatile downstream applications. Both control experiments and detailed DFT calculations suggest the formation of a key CPD ion intermediate that undergoes an unprecedented ring‐opening rearrangement of such species to furnish the product. Despite the pronounced complexity of the reaction pathway, which requires precise selectivity control at nearly every step, comprehensive computational analysis of a range of possible transition states elucidates the unusual reactivity and underlying origin of the observed selectivity.