Synthesis of a New Chiral <i>N,N,N</i>-Tridentate Pyridinebisimidazoline Ligand Library and Its Application in Ru-Catalyzed Asymmetric Epoxidation
作者:Santosh Bhor、Gopinathan Anilkumar、Man Kin Tse、Markus Klawonn、Christian Döbler、Bianca Bitterlich、Anne Grotevendt、Matthias Beller
DOI:10.1021/ol050821e
日期:2005.8.1
A small ligand library of chiral tridentate N,N,N-pyridinebisimidazolines have been synthesized for the first time. This new class of ligands can be easily tuned and synthesized on multi g-scale. The usefulness of the ligands is shown in the ruthenium-catalyzed asymmetric epoxidation with hydrogenperoxide as oxidant. Excellent yields (>99%) and good enantioselectivities (up to 71% ee) have been obtained
Synthesis of a novel class of chiral N,N,N-tridentate pyridinebisimidazoline ligands and their application in Ru-catalyzed asymmetric epoxidations
作者:Gopinathan Anilkumar、Santosh Bhor、Man Kin Tse、Markus Klawonn、Bianca Bitterlich、Matthias Beller
DOI:10.1016/j.tetasy.2005.08.060
日期:2005.10
A new class of easily tunable N,N,N-pyridinebisimidazoline (pybim) ligands have been synthesized. The synthesis and tunability of these chiral tridentate ligands are much easier and flexible compared to the popular pyboxes, making the former a suitable ligand tool box for various asymmetric transformations. Ruthenium complexes of the new ligands were synthesized and applied in the asymmetric epoxidation of olefins using hydrogen peroxide as the oxidant. Excellent yields and moderate to good enantioselectivities were achieved in the epoxidation of aromatic olefins. (c) 2005 Elsevier Ltd. All rights reserved.