We prepared a new class of chiral 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 diastereomeric catalysts from a single diene precursor. The bisboranes prepared in situ exhibited excellent activity (turnover numbers up to 200 at −40 °C) and enantioselectivity (up to 95 % ee) in imine hydrogenation reactions.

中文翻译：

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C2对称双环双硼烷催化剂：可逆的二烯加氢硼化反应的动力学或热力学产物

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）。