Palladium-catalyzed highly diastereoselective cascade dihalogenation of alkyne-tethered cyclohexadienones via Umpolung of palladium enolate.

Herein, we report a highly diastereo- and regioselective dihalogenation of alkyne-tethered cyclohexadienones for the synthesis of cis-hydrobenzofurans. One carbon-carbon and two carbon-halogen bonds were formed in an efficient manner and three contiguous stereocenters were generated. The reaction proceeds through cis-halopalladation, migratory insertion followed by a nucleophilic attack of a halide anion on a palladium enolate.