Catalytic Asymmetric Hydroboration of α-Substituted Styrenyl Derivatives

Significance

1,1-Disubstituted olefins represent a group of challenging substrates for asymmetric transformations, generally providing lower stereoselectivities than other alkenes. Using these starting materials, the rhodium-mediated β-hydroboration was found to be suppressed by the α-pathway. In this paper, iridium catalysis is used to accomplish the enantioselective β-hydroboration of terminal alkenes with high catalytic activity, perfect regioselectivity, and ee values up to 92%. The catalytic asymmetric hydroboration remains one of the long-standing problems, which can hopefully be solved via iridium catalysis.