An efficient and mild ruthenium-catalyzed racemization of amines: application to the synthesis of enantiomerically pure amines

Pàmies, Òscar; Éll, Alida H.; Samec, Joseph S. M.; Hermanns, Nina; Bäckvall, Jan‐E.

doi:10.1016/s0040-4039(02)00817-1

Cited by 134 publications

(91 citation statements)

References 19 publications

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“…Scheme 1, X¼NH). In 2002, B€ ackvall and coworkers reported on an efficient ruthenium-catalyzed racemization of aromatic amines under transfer hydrogenation conditions using Shvo's catalyst 1 [18]. At first the method suffered from considerable amounts of by-product formation, but addition of a hydrogen donor, 2,4-dimethyl-3-pentanol, was found to suppress the formation of these side products.…”

Section: Racemization Of Aminesmentioning

confidence: 99%

“…Scheme 33 DKR of primary alcohols has been applied to various derivatives of tropic acid ethyl esters with the use of Shvo's catalyst 1 and P. cepacia lipase (PS-C) as the enzyme [81]. The products were obtained with (S)-selectivity in high yields (60-88%) and with ee values exceeding 90% for several substrates (18). No external hydrogen source was required for the efficiency of the reaction as for many DKR protocols for secondary alcohols.…”

Section: Dkr Of Primary Alcoholsmentioning

confidence: 99%

“…4.2.3.2 was also combined with an enzymatic kinetic resolution of primary amines in a two-step manner (Scheme 34) [18]. CALB was used for the kinetic resolution.…”

Section: Dkr Of Primary Aminesmentioning

confidence: 99%

“…Since then it has been widely applied in various hydrogen transfer reactions, including hydrogenation of carbonyl compounds [2,3], transfer hydrogenation of ketones and imines [4,5], disproportion of aldehydes to esters [6], and Oppenauer-type oxidations of alcohols [7][8][9] and amines [10][11][12]. Shvo's complex 1 has also been found to be effective as a racemization catalyst for secondary alcohols and amines, and complex 1 has therefore been used together with enzymes in several dynamic kinetic resolution (DKR) protocols [13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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This chapter reviews the use of Shvo's catalyst in various hydrogen transfer reactions and also discusses the mechanism of the hydrogen transfer. The Shvo catalyst is very mild to use since no activation by base is required in the transfer hydrogenation of ketones or imines or in the transfer dehydrogenation of alcohols and amines. The Shvo catalyst has also been used as an efficient racemization catalyst for alcohols and amines. Many applications of the racemization reaction are found in the combination with enzymatic resolution leading to a dynamic kinetic resolution (DKR). In these dynamic resolutions, the yield based on the starting material can theoretically reach 100%. The mechanism of the hydrogen transfer from the Shvo catalyst to ketones (aldehydes) and imines as well as the dehydrogenation of alcohols and amines has been studied in detail over the past decade. It has been found that for ketones (aldehydes) and alcohols, there is a concerted transfer of the two hydrogens involved, whereas for typical amines and imines, there is a stepwise transfer of the two hydrogens. One important question is whether the substrate is coordinated to the metal or not in the hydrogen transfer step(s). The pathway involving coordination to activate the substrate is called the inner-sphere mechanism, whereas transfer of hydrogen without coordination is called the outer-sphere mechanism. These mechanistic proposals together with experimental and theoretical studies are discussed.

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Section: Racemization Of Aminesmentioning

confidence: 99%

Section: Dkr Of Primary Alcoholsmentioning

confidence: 99%

“…4.2.3.2 was also combined with an enzymatic kinetic resolution of primary amines in a two-step manner (Scheme 34) [18]. CALB was used for the kinetic resolution.…”

Section: Dkr Of Primary Aminesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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“…Ruthenium complexes of electronically coupled cyclopentadienone ligands catalyze a brought range of homogeneous hydrogen transfer reactions such as disproportionation of aldehydes to esters, [1] reduction of aldehydes and ketones, [2] Oppenauer type oxidations of alcohols and amines, [3,4] racemisation of alcohols and amines [5,6] and the oxidation of alcohols without hydrogen acceptor. [7] The Shov complex [{(η 5 -Ph 4 C 4 CO) 2 H}Ru 2 (CO) 4 (µ-H)] represents the most famous catalyst of this type.…”

Section: Introductionmentioning

confidence: 99%

Ruthenium Complexes of Electronically Coupled Cyclopentadienone Ligands – Catalysts for Transformations of Propargyl Alcohols

Haak

2007

Eur J Org Chem

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A series of donor‐ and acceptor‐substituted ruthenium cyclopentadienone complexes were synthesized and their catalytic activities towards propargyl alcohols focused on amination reactions have been investigated. It is shown that the substituents of the cyclopentadienone ligand determine the mode of activation of propargyl alcohols by these complexes leading to different central intermediates in catalytic cycles. Catalytic transformations of propargyl alcohols to α‐ or β‐amino ketones, enamino ketones, α,β‐unsaturated imines, ketones, alkenes and conjugated enynes could be achieved. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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1-Hydroxytetraphenylcyclopentadienyl(tetraphenyl-2,4-cyclopentadien-1-one)-μ-hydrotetracarbonyldiruthenium(II)

Samec

Bäckvall

2009

Encyclopedia of Reagents for Organic Synthesis

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An efficient and mild ruthenium-catalyzed racemization of amines: application to the synthesis of enantiomerically pure amines

Cited by 134 publications

References 19 publications

Shvo’s Catalyst in Hydrogen Transfer Reactions

Shvo’s Catalyst in Hydrogen Transfer Reactions

Ruthenium Complexes of Electronically Coupled Cyclopentadienone Ligands – Catalysts for Transformations of Propargyl Alcohols

1-Hydroxytetraphenylcyclopentadienyl(tetraphenyl-2,4-cyclopentadien-1-one)-μ-hydrotetracarbonyldiruthenium(II)

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