Highly Enantioselective Rhodium-Catalyzed Cross-Addition of Silylacetylenes to Cyclohexadienone-Tethered Internal Alkynes.

The first highly enantioselective rhodium-catalyzed cross-addition of silylacetylenes to cyclohexadienone-tethered internal alkynes has been achieved via a tandem process: regioselective alkynylation of the internal alkynes and subsequent intramolecular conjugate addition to the cyclohexadienones, affording the cis-hydrobenzofuran frameworks with good yields (up to 88% yield) and excellent enantioselectivities (90%-96% ee). This mild reaction showed perfect atom economy and broad functional group tolerance. Furthermore, a gram-scale experiment and diverse further conversions of the cyclization products were also presented.