Rhodium/MonoPhos-Catalysed Asymmetric Hydrogenation of Enamides

Berg, Michel van den; Haak, Robert M.; Minnaard, Adriaan J.; Vries, André H.M. de; Vries, Johannes G. de; Feringa, Bernard

doi:10.1002/1615-4169(200210)344:9<1003::aid-adsc1003>3.0.co;2-m

Cited by 106 publications

(33 citation statements)

References 22 publications

(34 reference statements)

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“…By using the rhodium complex bearing a chiral spirobiindane phosphoramidite ligand SIPHOS, a variety of enamides can be hydrogenated to produce the corresponding amines with excellent enantioselectivities. Chan [16] and de Vries and Feringa [17] independently demonstrated that the monophosphoramidite ligands with a binaphthyl backbone were also efficient ligands for the rhodiumcatalyzed asymmetric hydrogenation of enamides. The monophosphite ligands with a binaphthyl structure were introduced into this asymmetric hydrogenation reaction by Reetz et al [18].…”

Section: Asymmetric Hydrogenation Of Enamidesmentioning

confidence: 99%

“…Chan [16] and de Vries and Feringa [17] independently reported that the rhodium complex bearing a MonoPhos (3a, Scheme 8.4) was an efficient catalyst for the asymmetric hydrogenation of enamides. Under the conditions of 1 mol% catalyst generated in situ from [Rh(COD) 2 ]BF 4 with 2 equiv of MonoPhos in dichloromethane, under 300 psi H 2 at low reaction temperature (À20 C), the substrate 7a was reduced to N-acetyl amine 8a with 95% ee (Scheme 8.4).…”

Section: Asymmetric Hydrogenation Of Enamidesmentioning

confidence: 99%

“…They achieved high enantioselectivities for the rhodium-catalyzed asymmetric hydrogenation of 1-(1,2-diarylvinyl)pyrrolidines (Schemes 8. 17 synthesis of chiral tertiary amines [52]. In the presence of 2 mol% I 2 and 20 mol% HOAc as additives and the rhodium catalyst generated in situ from 1 mol% [Rh (COD) 2 ]BF 4 and 2.2 mol% chiral monophosphonite 39c (Scheme 8.17), the enamine 1-(1,2-diphenylvinyl)pyrrolidine (37a) was hydrogenated smoothly in THF under 10 bar of hydrogen pressure at room temperature to provide chiral amine 38a in 100% conversion with 87% ee within 12 h (Scheme 8.18).…”

Section: Asymmetric Hydrogenation Of Nn-dialkyl Enaminesmentioning

confidence: 99%

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Enantioselective Hydrogenation of Enamines with Monodentate Phosphorus Ligands

Zhou

Xie

2010

Chiral Amine Synthesis

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Chiral amines are widely used as chiral ligands, auxiliaries, resolving agents, and important intermediates in synthetic chemistry. Asymmetric hydrogenation of enamines such as enamides is an atom economic and straightforward protocol for the preparation of chiral amines. In 1972, Kagan reported the first example of asymmetric hydrogenation of enamides with chiral Rh-DIOP complex as a catalyst [1]. This opened a new window for the asymmetric synthesis of chiral N-acyl amines although the enantioselectivity of the reaction was not more than 78% ee (Scheme 8.1). When Noyori et al. introduced chiral Ru-BINAP, it significantly increased the level of enantioselectivity to 99.5% ee in the asymmetric hydrogenation of N-acyl-1-alkylidenetetrahydroisoquinolines [2]. However, this ruthenium-catalyzed asymmetric hydrogenation is very sensitive to the stereochemistry of the enamide, with only the (Z)-isomer of the enamide being hydrogenated while the (E)-isomer was recovered intact (Scheme 8.2). Another breakthrough in this field came in 1996 when Burk et al. showed that chiral rhodium complexes bearing a diphosphine ligand Me-DuPHOS or Me-BPE could hydrogenate a-arylenamides to yield a wide variety of valuable a-1-arylethylamine derivatives with high enantioselectivities (up to 98.5% ee) (Scheme 8.3) [3]. The merit of this hydrogenation is that both (E)-and (Z)-isomers of b-substituted enamides can be hydrogenated, thus enlarging the substrate scope of the reaction. Subsequently, many efficient diphosphines, such as BICP (bis(diphenylphosphino)dicyclopentane) [4], PennPhosP, NHAc NHAc 1 bar H 2 [RhCl(COD) 2 ] 2 /(S,S)-DIOP EtOH-C 6 H 6 (2 :1), rt 95% yield, 78% ee PPh 2 PPh 2 O O (S,S)-DIOP Scheme 8.1 Rh-DIOP catalyzed asymmetric hydrogenation of enamides.

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Section: Asymmetric Hydrogenation Of Enamidesmentioning

confidence: 99%

Section: Asymmetric Hydrogenation Of Enamidesmentioning

confidence: 99%

Section: Asymmetric Hydrogenation Of Nn-dialkyl Enaminesmentioning

confidence: 99%

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Enantioselective Hydrogenation of Enamines with Monodentate Phosphorus Ligands

Zhou

Xie

2010

Chiral Amine Synthesis

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“…3 A recent breakthrough in the field has been the development of monodentate phosphoramidites, 4 phosphonites, 5 phosphites, 6 and phosphines 7 for the highly enantioselective hydrogenation of a-and b-dehydroamino acids, 8 and enamides. 9 Other groups have developed monodentate ligands that also perform well in asymmetric hydrogenation. We recently reported on the successful use of monodentate secondary phosphine oxide ligands in iridium-catalyzed asymmetric imine hydrogenation.…”

Section: Introductionmentioning

confidence: 99%

The application of monodentate secondary phosphine oxide ligands in rhodium- and iridium-catalyzed asymmetric hydrogenation

Jiang

Berg

Minnaard

et al. 2004

Tetrahedron: Asymmetry

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The application of monodentate secondary phosphine oxide ligands in rhodium-and iridiumcatalyzed asymmetric hydrogenation Jiang, Xiao-bin; van den Berg, Michel; Minnaard, Adriaan; de Vries, Johannes G.; Feringa, B.L. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Abstract-Enantiopure secondary phosphine oxides have been tested as ligands in the rhodium-and iridium-catalyzed asymmetric hydrogenation of functionalized olefins. tert-Butylphosphinoyl benzene turned out to be a versatile ligand in the iridium-catalyzed hydrogenation of b-branched dehydroamino esters and in the rhodium-catalyzed hydrogenation of an enol carbamate.

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“…Use of a monodentate phosphoramide catalyst 13 also proved unrewarding, failing to give any identifiable hydrogenation products. Discouraged by the lack of even modest selectivity in this initial screening, we quickly turned our efforts to the synthesis of racemic material.…”

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confidence: 99%