Photoredox-Catalyzed Strain-Release-Driven Aminopyridylation of Bicyclo[1.1.0]butanes with <i>N</i> -Aminopyridinium Ylides

An unprecedented visible-light-induced strain-release-driven aminopyridylation of bicyclo[1.1.0]butanes with bench-stable and easily accessible <i>N</i>-aminopyridinium ylides was developed. The photoredox-catalyzed transformation proceeds through amidyl-radical-mediated scission of the central C-C bond of bicyclo[1.1.0]butanes followed by intramolecular annulation and homolytic N-N bond cleavage. This cascade reaction delivers biologically and pharmaceutically prominent pyridine-containing polysubstituted cyclobutanecarboxamides in a regio- and diastereoseletive manner. The cyclobutanecarboxamides have a high fraction of sp³-hybridized carbon atoms. This reaction features mild metal-free conditions, excellent functional group compatibility, high atom economy, and potential for downstream late-stage functionalization.