Ruthenium Complexes Containing Chiral N‐Donor Ligands as Catalysts in Acetophenone Hydrogen Transfer – New Amino Effect on Enantioselectivity

Gómez, Montserrat; Jansat, Susanna; Muller, Guillermo; Aullón, Gabriel; Maestro, Miguel A.

doi:10.1002/ejic.200500515

Cited by 21 publications

(2 citation statements)

References 44 publications

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“…The first step for the synthesis of 1,2,3-benzotriazinones was the preparation of 2-(o-aminophenyl)oxazolines 3a-3c (see (1)). These oxazolines were prepared in high yields (58-80%) by cyclization of anthranilonitrile with ethanolamines under basic conditions in a mixture of glycerol and ethylene glycol, following the methodology reported by Gómez and coworkers [19]. In the literature, it has been reported that oxazolines 3a and 3b were obtained as oils, whereas in our work both were isolated as solids; we believe this fact is due to problems in the purification process in the previous report.…”

Section: Resultsmentioning

confidence: 54%

A Novel Synthesis of 1,2,3-Benzotriazinones from 2-(o-Aminophenyl)oxazolines

Rocha-Alonzo

Chávez

Ochoa-Terán

et al. 2017

Journal of Chemistry

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Section: Resultsmentioning

confidence: 54%

A Novel Synthesis of 1,2,3-Benzotriazinones from 2-(o-Aminophenyl)oxazolines

Rocha-Alonzo

Chávez

Ochoa-Terán

et al. 2017

Journal of Chemistry

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“…33,34 Formation of the compounds containing Ru-H from Ru-Cl precursors are well-documented 35 such as in situ generated Ru-H species can act as the active catalysts for transfer hydrogenation of ketones. [36][37][38] The proposed mechanism of transfer hydrogenation of ketone using catalysts reported in the manuscript is depicted in Scheme 4.…”

Section: Scheme 1 Synthesis Of N-substituted Imidazoline and Benzimimentioning

confidence: 99%

Transfer hydrogenation of ketones in the presence of half sandwich ruthenium (II) complexes bearing imidazoline and benzimidazole ligand

Şahin¹,

Demır²,

Özdemır³

2014

Arkivoc

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This article explores the possibility of using imidazoline and benzimidazole derivatives as interesting ligands due to the fact that they are structurally simple, readily available, inexpensive, and they allow easy introduction of various substituents into their structure. Therefore, Nsubstituted imidazoline and benzimidazole ligands and their new ruthenium complexes [RuCl 2 (η 6 -p-cymene)(L)] (L = N-substituted imidazoline/benzimidazole) were synthesized and characterized. The catalytic performances of new complexes are investigated for the transfer hydrogenation of ketones. Furthermore, corresponding secondary alcohols were also obtained in good yields.

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New Ruthenium Catalysts for Asymmetric Transfer Hydrogenation of Prochiral Ketones

et al. 2007

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Tridentate N,N,N-pyridinebisimidazolines have been studied as new ligands for the enantioselective transfer hydrogenation of prochiral ketones. High yields and excellent enantioselectivity up to > 99 % ee have been achieved with an in situ generated catalytic system containing dichlorotris(triphenylphosphine)ruthenium and 2,6-bis-([4R,5R]-4,5-diphenyl-4,5-dihydro-1H-imidazol-2-yl)-pyridine (3a) in the presence of sodium isopropoxide.Keywords: asymmetric transfer hydrogenation; ketones; phosphines; ruthenium; tridentate nitrogen ligands Enantiomerically pure alcohols have a wide range of applications, for example, building blocks and synthons for pharmaceuticals, agrochemicals, polymers, syntheses of natural compounds, auxiliaries, ligands and key intermediates in organic syntheses.[1] Within the different molecular transformations to chiral alcohols, transition metal-catalyzed reactions offer efficient and versatile strategies, such as addition of organometallic compounds to aldehydes, hydrosilylation, and hydrogenation of prochiral ketones.[2] From an economic and environmental point of view the asymmetric hydrogenation, in particular the transfer hydrogenation, represents a powerful tool for their synthesis because of its high atom economy and safety advantages.[3] Here, Noyoris ruthenium-based catalysts comprising chiral tosylated diamines constitute state-of-the-art transfer hydrogenation systems.[3d,4] Based on this seminal work an increasing number of ruthenium catalysts with chiral bidentate N,N-ligands were developed in the last decade.[3] Significantly fewer systems are known in which transfer of chiral information is promoted by tridentate ligands. [5,6] Up to now only a limited number of auspicious tridentate nitrogen-containing N,N,N ligands were established in the field of transfer hydrogenation. For example (R)-phenyl-ambox (1) [5] and different pyridinebisoxazoline (pybox) ligands (2) [6] have been applied for the reduction of acetophenone (Scheme 1).Recently, we reported the synthesis of a new class of chiral tridentate amines.[7] The preparation and tunability of these pyridinebisimidazolines (3) (socalled pybim ligands, Scheme 1) are easier and more flexible compared to the popular pyboxes, making the former a suitable ligand tool box for various asymmetric transformations. To date there is no report on the performance of these ligands in hydrogenation reactions. The resemblance between pybim (3) and pybox (2) stimulated our research to study the potential of this class of ligands in the transfer hydrogenation of aromatic and aliphatic ketones.In exploratory experiments, isopropyl alcohol-based transfer hydrogenation of acetophenone was examined using a simple in situ catalyst system composed of [RuCl 2

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Ruthenium Complexes Containing Chiral N‐Donor Ligands as Catalysts in Acetophenone Hydrogen Transfer – New Amino Effect on Enantioselectivity

Cited by 21 publications

References 44 publications

A Novel Synthesis of 1,2,3-Benzotriazinones from 2-(o-Aminophenyl)oxazolines

A Novel Synthesis of 1,2,3-Benzotriazinones from 2-(o-Aminophenyl)oxazolines

Transfer hydrogenation of ketones in the presence of half sandwich ruthenium (II) complexes bearing imidazoline and benzimidazole ligand

New Ruthenium Catalysts for Asymmetric Transfer Hydrogenation of Prochiral Ketones

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