The site-selective functionalization of C(sp2)–H bonds represents a powerful
strategy for the synthesis of structurally diverse compounds with broad
applicability. Here we report efcient regioselective catalytic methods for the
formation of benzyltrimethylsilanes through ruthenium-catalysed C(sp2)–H
silylmethylation. The developed protocols enable selective functionalization
at both ortho and meta positions within arenes bearing N-based directing
groups. The resulting silylmethyl compounds can undergo diverse transformations, including nucleophilic aromatic substitution, carbonyl
addition, olefnation and desilylation. Signifcantly, the regiodivergent
installation of silylmethyl synthetic handles allows for the synthesis of the
pharmaceutical losmapimod and could further be applied in direct late-stage
functionalizations. Mechanistically, an essential role for biscyclometallated
ruthenium(II) species has been found, with the formation of intermediate
ruthenium(III) species indicated by paramagnetic NMR experiments. These
synthetic inventions and mechanistic elucidations signify a transformative
step within ruthenium-catalysed C(sp2)–H functionalization, enabling diverse syntheses and providing a framework for future development.