Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Science. 2020 Mar 13;367(6483):1246-1251. doi: 10.1126/science.aba1120.
Chiral cations have been used extensively as organocatalysts, but their application to rendering transition metal-catalyzed processes enantioselective remains rare. This is despite the success of the analogous charge-inverted strategy in which cationic metal complexes are paired with chiral anions. We report here a strategy to render a common bipyridine ligand anionic and pair its iridium complexes with a chiral cation derived from quinine. We have applied these ion-paired complexes to long-range asymmetric induction in the desymmetrization of the geminal diaryl motif, located on a carbon or phosphorus center, by enantioselective C-H borylation. In principle, numerous common classes of ligand could likewise be amenable to this approach.
手性阳离子被广泛用作有机催化剂，但将其应用于过渡金属催化过程的对映选择性仍然很少见。尽管类似的电荷反转策略取得了成功，其中阳离子金属配合物与手性阴离子配对。我们在这里报告了一种将常见的联吡啶配体阴离子化并将其铱配合物与来源于金鸡纳碱的手性阳离子配对的策略。我们已经将这些离子对配合物应用于通过对映选择性 C-H 硼化作用对位于碳或磷中心的偕二芳基基序的去对称化来实现远程不对称诱导。原则上，同样可以采用许多常见的配体类别。
