Chiral Dienes as “Ligands” for Borane-Catalyzed Metal-Free Asymmetric Hydrogenation of Imines
作者:Yongbing Liu、Haifeng Du
DOI:10.1021/ja4025808
日期:2013.5.8
This paper describes a highly enantioselective metal-free hydrogenation of imines using chiral dienes as "ligands" for the generation of catalysts with HB(C6F5)2 by hydroboration in situ to furnish a variety of chiral amines with up to 89% ee, which provides a practical strategy for the development of novel chiralfrustratedLewispairs for asymmetric hydrogenation.
本文描述了使用手性二烯作为“配体”对亚胺进行高度对映选择性的无金属氢化,通过原位硼氢化反应生成具有 HB(C6F5)2 的催化剂,以提供各种手性胺,其 ee 高达 89%,从而提供开发用于不对称氢化的新型手性受阻路易斯对的实用策略。
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‐Symmetric Bicyclic Bisborane Catalysts: Kinetic or Thermodynamic Products of a Reversible Hydroboration of Dienes
作者:Xian‐Shuang Tu、Ning‐Ning Zeng、Ru‐Ye Li、Yu‐Quan Zhao、De‐Zhen Xie、Qian Peng、Xiao‐Chen Wang
DOI:10.1002/anie.201808289
日期:2018.11.12
C2‐symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C6F5)2, and an analogue, HB(p‐C6F4H)2. The dependence of the addition pattern on the reaction temperature allowed us to selectively prepare two diastereomericcatalysts from a single diene precursor. The bisboranes prepared in situ exhibited excellent activity (turnover numbers up to 200 at −40 °C)
我们通过内部二烯与Piers硼烷HB(C 6 F 5)2和类似物HB(p- C 6 F 4 H)2的加成反应制备了新型的手性C 2对称双环双硼烷催化剂。加料方式对反应温度的依赖性使我们能够从单一的二烯前体中选择性地制备两种非对映体催化剂。原位制备的双硼烷在亚胺加氢反应中表现出出色的活性(在-40°C时的转换数高达200)和对映选择性(高达95% ee)。
Cooperative Catalysis with Iron and a Chiral Brønsted Acid for Asymmetric Reductive Amination of Ketones
AbstractThe direct asymmetric reductive amination (DARA) of ketones with anilines is described by combining a chiral Brønsted acid (TRIP) and the non‐chiral Knölker iron complex as the catalyst system. In situ‐formed imines are reduced with molecular hydrogen to give chiral amines in high yields (90%) and enantioselectivities of up to 99% ee.magnified image