E163-03-5 - Forschungsgruppe Nachhaltige organische Synthese und Katalyse
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Journal:
ACS Sustainable Chemistry & Engineering
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ISSN:
2168-0485
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Date (published):
4-Feb-2019
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Number of Pages:
10
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Publisher:
ACS
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Peer reviewed:
Yes
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Keywords:
Ruthenium; Chiral ligands; Transfer Hydrogenation; Asymmetric synthesis; Water
en
Abstract:
We report the design and synthesis of novel ion-tagged chiral ligands for asymmetric transfer hydrogenation (ATH) in aqueous medium. Based on (R,R)-1,2-diphenylethylene diamine (DPEN) as structural motif, a straightforward three-step protocol was developed that gave access to novel chiral ligands with carbamate-substructure and pyridinium headgroup. The careful optimization of steric and electronic properties in combination with the adaption of solubility via choice of the anion gave a set of chiral and water-soluble ligands for use in ruthenium-catalyzed asymmetric transfer hydrogenations in aqueous medium. Eventually, a pool of aliphatic and aromatic ketones as well as two imine substrates were reduced with excellent isolated yields up to 95% and enantioselectivities >90% ee under environmentally benign conditions in the absence of additional surfactants.
