Divergent ring opening and functionalization of N-alkyl aziridines via boryl radical fragmentation

Aziridine ring opening is a powerful platform for molecular diversification. Unactivated N-alkyl aziridines have long resisted ring opening and cross-coupling, so the installation and removal of N-activating groups followed by N-alkylation remains the most applicable route for aziridine diversification. Here we report a general radical activation mode that directly engages N-alkyl aziridines in ring-opening and divergent functionalization. Coordination of BH3 generates stable aziridine-ligated borane complexes that are selectively converted into aziridine-ligated boryl radicals. These species undergo regioselective β-scission to form β-aminoalkyl radicals that can be intercepted in metal-catalysed cross-coupling reactions. Two complementary platforms were developed: an oxidative copper catalytic system engaging aryl boronic acids, as well as nitrile and sulfide nucleophiles, and a dual photo–nickel catalytic system for cross-coupling with electrophilic aryl bromides. Together, these results establish a general strategy to directly engage N-alkyl aziridines in divergent ring opening and functionalization, thus streamlining access to β-functionalized amines.