Enantioselective remote C–H activation directed by a chiral cation

Asymmetry on the plus side Numerous positively charged metal catalysts have been paired with chiral negative ions to select for just one of two mirror-image products. Genov et al. now report a potentially general strategy to invert the charges in this paradigm. Because intrinsically negative metal catalysts are comparatively rare, the authors appended a sulfonate group to the common bipyridyl ligand. Iridium complexes of this ligand paired with chiral positive ions could borylate just one of two aryl rings appended to carbon or phosphorus centers with high enantioselectivity. Science , this issue p. 1246