Ligand design broadens NiI-catalysed C(sp2)–heteroatom couplings of aryl bromides at low catalyst loadings

Abstract

The formation of C(sp2)–heteroatom bonds through cross-coupling catalysis is central to the synthesis of pharmaceuticals, agrochemicals and materials. Whereas Pd0/PdII catalysis requires substrate-specific ligand optimization to balance the competing demands of oxidative addition and reductive elimination, NiI/NiIII catalysis offers a complementary strategy because the bond-forming step is intrinsically favourable. However, contemporary NiI/NiIII methodologies suffer from insufficient oxidative addition reactivity, restricting the aryl halide scope and requiring high catalyst loadings. Here we show that mechanistically guided ligand design overcomes these limitations. Together with a non-nucleophilic base additive that promotes direct visible-light generation of NiI from a bench-stable NiII precatalyst, this ligand design enables the coupling of electron-rich aryl bromides with N-, O-, S- and P-based nucleophiles at nickel loadings as low as 100 ppm. The method is compatible with sterically encumbered nucleophiles and enables gram-scale synthesis and late-stage functionalization of complex molecules.