Pd(II)-Catalyzed Asymmetric Annulation toward the Synthesis of 2,3-Disubstituted Chiral Indenols

An enantioselective asymmetric annulation of 2-formylboronic acids with internal alkynes has been realized using a chiral phosphinooxazoline/palladium­(II) catalyst. The reaction tolerates a variety of alkynes including the relatively inert diaryl substituted internal ones. A wide range of optically active 2,3-disubstituted indenols was afforded in high yields with good to excellent enantioselectivities (up to 99% yield and 99% ee).