C 2 ‐Symmetric Bicyclic Bisborane Catalysts: Kinetic or Thermodynamic Products of a Reversible Hydroboration of Dienes

We prepared a new class of chiral C 2 ‐symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C 6 F 5 ) 2 , and an analogue, HB( p ‐C 6 F 4 H) 2 . The dependence of the addition pattern on the reaction temperature allowed us to selectively prepare t...

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Bibliographic Details
Published inAngewandte Chemie International Edition Vol. 57; no. 46; pp. 15096 - 15100
Main Authors Tu, Xian‐Shuang, Zeng, Ning‐Ning, Li, Ru‐Ye, Zhao, Yu‐Quan, Xie, De‐Zhen, Peng, Qian, Wang, Xiao‐Chen
Format Journal Article
LanguageEnglish
Published Germany 12.11.2018
Subjects
asymmetric catalysis
homogeneous catalysis
boron
hydrogenation
frustrated Lewis pairs
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Summary:We prepared a new class of chiral C 2 ‐symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C 6 F 5 ) 2 , and an analogue, HB( p ‐C 6 F 4 H) 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.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201808289