Practical synthesis of new and highly efficient ligands for the Suzuki reaction of aryl chlorides

Zapf, Alexander; Jackstell, Ralf; Rataboul, Franck; Riermeier, Thomas H.; Monsees, Axel; Fuhrmann, Christa; Shaikh, Nadim S.; Dingerdissen, Uwe; Beller, Matthias

doi:10.1039/b311268n

Cited by 250 publications

(108 citation statements)

References 27 publications

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“…All ketones were dried over CaH 2 , distilled in vacuum and stored under argon, except 4'-methoxyacetophenone and phenacyl chloride, which were used without further purification. BuP(Ad) 2 [19] and N-phenyl-2-(di-tert-butylphosphino)-pyrrole [20] were synthesized according to literature protocols.…”

Section: Experimental Section General Remarksmentioning

confidence: 99%

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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Section: Experimental Section General Remarksmentioning

confidence: 99%

New Ruthenium Catalysts for Asymmetric Transfer Hydrogenation of Prochiral Ketones

et al. 2007

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“…Among the approaches described in the literature, numerous efforts have been devoted to the development of ligand-promoted catalytic systems. The groups of Fu, [4] Buchwald, [5] Beller, [6] Herrmann, [7] Bedford, [8] Nolan, [9] and others [10] have achieved significant success.…”

Section: Introductionmentioning

confidence: 99%

Aerobic Ligand‐Free Suzuki Coupling Reaction of Aryl Chlorides Catalyzed by In Situ Generated Palladium Nanoparticles at Room Temperature

2008

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An aerobic, ligand-free Suzuki coupling reaction catalyzed by in situ generated palladium nanoparticles in polyethylene glycol with an average molecular weight of 400 Da (PEG-400) at room temperature has been developed. This catalytic system is a very simple and highly active protocol for the Suzuki coupling of aryl chlorides with arylboronic acids, which proceed smoothly in excellent yields in short times using low catalyst loadings. Control experiments demonstrated that the Suzuki reaction catalyzed by the in situ generated palladium nanoparticles can be carried out much quicker than that using the preprepared particles under the same conditions. The formation of palladium nanoparticles in PEG-400 was promoted by arylboronic acids.

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“…Notable recent catalyst developments for the use of aryl chlorides [6] have been reported by Bedford, [7] Buchwald, [8] Fu, [9] Herrmann, [10] Nolan, [11] us, [12] and others. [13] In addition, our group has reported the use of di-(1-adamantyl)-n-butylphosphine [12c,14] and N-aryl-2-(dialkylphosphino)pyrrole/indole as highly active ligands for the coupling of a wide range of aryl chlorides with phenylboronic acid [12a] and amines, [15] respectively.…”

Section: Introductionmentioning

confidence: 99%

Dialkylphosphinoimidazoles as New Ligands for Palladium‐Catalyzed Coupling Reactions of Aryl Chlorides

et al. 2004

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Practical synthesis of new and highly efficient ligands for the Suzuki reaction of aryl chlorides

Cited by 250 publications

References 27 publications

New Ruthenium Catalysts for Asymmetric Transfer Hydrogenation of Prochiral Ketones

New Ruthenium Catalysts for Asymmetric Transfer Hydrogenation of Prochiral Ketones

Aerobic Ligand‐Free Suzuki Coupling Reaction of Aryl Chlorides Catalyzed by In Situ Generated Palladium Nanoparticles at Room Temperature

Dialkylphosphinoimidazoles as New Ligands for Palladium‐Catalyzed Coupling Reactions of Aryl Chlorides

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