Copper-catalyzed stereo- and regioselective borylalkylation of silicon-tethered haloalkyl alkynes to access borylated benzosilolines

An efficient and practical route for the preparation of various functionalized benzosiloline derivatives via copper-catalyzed stereo- and regioselective borylalkylation reaction has been developed. Starting from silicon-tethered haloalkyl alkynes, a series of valuable benzosiloline and 2,3-dihydro-1-sila-1H-phenalene frameworks possessing a borylated exo-vinylidene moiety were efficiently prepared, which have high synthetic utility and are difficult to obtain in other aspects.