Asymmetric Hydrogenation of α‐Keto Phosphonates with Chiral Palladium Catalysts

Goulioukina, Nataliya S.; Bondarenko, G. N.; Bogdanov, Alexey V.; Gavrilov, K. N.; Beletskaya, I. P.

doi:10.1002/ejoc.200800943

Cited by 59 publications

(27 citation statements)

References 72 publications

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“…The asymmetric hydrogenations of a-phthalimide ketones and a-keto phosphonates with palladium catalyst systems were reported by us [8] and Goulioukina, [9] respectively. In comparison, there are more reports on Pd-catalyzed asymmetric hydrogenations of activated imines.…”

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confidence: 88%

“…MeOH and CH 2 Cl 2 led to very low reactivity (entries 13 and 14); TFE was found to be the optimal solvent, which is in accordance with the Pd-catalyzed hydrogenation of ketones and activated imines in the literature. [8][9][10][11][12][13][14][15][16] Subsequently, some commercially available bisphosphine ligands were examined under the above conditions. The results showed that axial chiral bidentate bisphosphine ligands L1-L4 and L6-L8 (Table 2, entries 1-4 and 6-8) gave full conversions with 58-75% ee.…”

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Palladium‐Catalyzed Asymmetric Hydrogenation of Simple Ketimines Using a Brønsted Acid as Activator

2010

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Using a catalytic amount of a Brønsted acid as activator of simple imines, the highly enantioselective homogeneous palladium-catalyzed asymmetric hydrogenation of simple ketimines was successfully developed with up to 95% ee.Keywords: asymmetric hydrogenation; Brønsted acids; ketimines; palladium catalysisThe preparation of chiral amines from the transition metal-catalyzed asymmetric hydrogenation or transfer hydrogenation of prochiral imines represents one of the most direct and efficient approaches that open a straightforward route to valuable building blocks for natural products, pharmaceuticals and other fine chemical compounds.[1] A variety of chiral metal catalysts has been successfully applied to this reaction over the last few decades. Among the various catalytic systems so far, Ru, [2] Rh, [3] Ir [4] and organocatalysts [5] have been successfully employed in enantioselective hydrogenations and/or transfer hydrogenations of imines. Recently, Zhang and co-workers developed the first asymmetric hydrogenation of unprotected N À H iminiums with up to 95% ee using chiral iridium complexes as catalyst.[6] Although significant progress have been made in the enantioselective reduction of imines, the search for new catalytic systems is still highly desirable.Pd-based catalytic systems have been extensively employed for a wide range of useful synthetic organic transformations, [7] nevertheless, very little attention has been paid to homogeneous asymmetric hydrogenation with chiral Pd complexes. The asymmetric hydrogenations of a-phthalimide ketones and a-keto phosphonates with palladium catalyst systems were reported by us [8] and Goulioukina, [9] respectively. In comparison, there are more reports on Pd-catalyzed asymmetric hydrogenations of activated imines. The first hydrogenation of imino esters catalyzed by palladium complexes was described by Amii [10] and coworkers with up to 91% ee in 2001. Afterwards, highly enantioselectively Pd-catalyzed hydrogenations of N-diphenylphosphinyl ketimines and N-tosylimines were reported by us [11] and the Zhang [12] group, respectively [Scheme 1, Eq. (1)]. Since then, chiral palladium complexes have also been employed for the asymmetric hydrogenation of some other cyclic activated sulfonylimines in our laboratory. [13] In 2009, Rubio-PØrez [14] and co-workers reported the direct reductive amination of alkyl ketones catalyzed by chiral palladium complexes at 70 8C with up to 99% ee, but only moderate yield and low enantiomeric excess were observed in the amination of aryl ketones. Most recently, an efficient Pd-catalyzed asymmetric hydrogenation of simple indoles was developed by us with a Brønsted acid as activator.[15] Although much effort Scheme 1. Activation strategy for Pd-catalyzed asymmetric hydrogenation of simple ketimines.

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Palladium‐Catalyzed Asymmetric Hydrogenation of Simple Ketimines Using a Brønsted Acid as Activator

2010

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“…The absolute configuration of the C*ÀP stereocenter was established as (R) by anomalous dispersion effects in diffraction measurements on a single crystal (Figure 4). [41] Speaking of regularities observed, we can sum up that the homogeneous palladium-catalyzed hydrogenation of a-oxo phosphonates [35] and E-isomers of the corresponding oximes [14] and tosylimines [6] using (R)-ligands of the binaphthyl and biphenyl types provides (S)-enantiomers of the products, but the hydrogenation of Z-oximes and Z-phenylhydrazones affords (R)-enantiomers. A tentative mechanism for homogeneous Pd(II)-catalyzed asymmetric hydrogenation can be outlined on the basis of previous investigations of Zhou et al, [12c] which include isotope-labeling tests, [26,28,42] NMR experiments, and DFT calculations [28] and taking into account general mechanistic aspects.…”

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“…[26,28,35,37] Among atropoisomeric C 2 -symmetric bidentate ligands of the triarylphosphine type only (S)-2,2'-bis(diphenylphospino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl [(S)-H 8 -BINAP] (entry 4) showed an unsatisfactory result. It is worth mentioning that a characteristic feature of (S)-H 8 -BINAP is an appreciably increased dihedral angle between the planes of the aromatic fragments.…”

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One‐Pot Two‐Step Synthesis of Optically Active α‐Amino Phosphonates by Palladium‐Catalyzed Hydrogenation/Hydrogenolysis of α‐Hydrazono Phosphonates

et al. 2016

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An efficient and convenient one-pot procedure for the stereoselective catalytic synthesis of ring-substituted [amino(phenyl)methyl]phosphonates has been developed. The enantioselective hydrogenation of easily available diisopropyl (Z)-[aryl(phenylhydrazono)methyl]phosphonates using palladium(II) acetate as a precatalyst, (R)-2,2'-bis (diphenylphosphino)-5,5'-dichloro-6,6'-dimethoxy-1,1'-biphenyl [(R)-Cl-MeO-BIPHEP] as a ligand, and (1S)-(+)-10-camphorsulfonic acid as an activator in a mixture of 2,2,2-trifluoroethanol and methylene chloride at ambient temperature results in the formation of corresponding [aryl(2-phenylhydrazino)methyl]phosphonates. The subsequent cleavage of the NÀN bond has been accomplished with molecular hydrogen after the addition of palladium on carbon and methanol into crude reaction mixture to afford the optically active [amino(aryl)methyl]phosphonates. The method is operationally simple and provides an appreciable enantioselectivity up to 98 % ee.Keywords: a-amino phosphonates; asymmetric catalysis; a-hydrazono phosphonates; hydrogenation; palladium a-Amino phosphonates, particularly nonracemic ones, have been a topic for decades due to a wide spectrum of their possible applications.[1] Nevertheless, the stereocontrolled formation of a-amino phosphonates remains a challenge in chemical synthesis. Among catalytic concepts for the enantioselective synthesis of a-amino phosphonates, two methodologies are leading, namely, asymmetric hydrophosphonylation of aldimines and ketimines and asymmetric reduction of a,b-dehydroaminophosphonates.[2] Several years ago we reported on the feasibility of Rh-catalyzed asymmetric hydrogenation of a-imino phosphonates as a straightforward access to optically active a-amino phosphonates containing the quaternary b-carbon atom.[3] Subsequently, this approach was extended on oxazaborolidine catalyzed reduction of (2,2,2-trifluoro-1-iminoethyl)phosphonates with catecholeborane.[4] Along with all apparent advantages, some pitfalls of this method should be mentioned. First, aimino phosphonates are actually an equilibrium mixture of Z/E-isomers, which may have an adverse effect on the overall stereoselectivity of the process. In addition, these starting substrates are slowly hydrolyzed on storage. Finally, the common synthesis of aimino phosphonates via the Michaelis-Arbuzov rearrangement requires the usage of labile imidoyl chlorides under harsh reaction conditions.[5] When the present paper was in preparation, Zhou et al. communicated on excellent results in Pd-catalyzed asymmetric hydrogenation of a-tosylimino phosphonates. [6] However, the latter precursors cannot be considered the best choice, because they are synthesized from the same racemic a-tosylamino phosphonates by N-chlorination/dehydrochlorination procedure. [7] Readily accessible a-oxo phosphonates [8] are important reagents for the preparation of elaborate phosphonates. Unfortunately, they cannot be used for the synthesis of the corresponding a-imino phosphonates since the interaction of si...

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“…Recently, Goulioukina reported the asymmetric hydrogenation of a-ketophosphonates 115 catalyzed by Pd(OCOCF 3 ) 2 /(R)-MeO-BiPhep in TFE under atmospheric hydrogen pressure with up to 55% ee (Scheme 39) [129]. …”

Section: Adventure In Asymmetric Hydrogenationmentioning

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Adventure in Asymmetric Hydrogenation: Synthesis of Chiral Phosphorus Ligands and Asymmetric Hydrogenation of Heteroaromatics

Wang

et al. 2011

Asymmetric Catalysis From a Chinese Perspective

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Catalytic asymmetric hydrogenations of prochiral unsaturated compounds, such as olefins, ketones, and imines, have been intensively studied and are considered as a versatile method of the synthesis of chiral compounds due to atom economy and operational simplicity. Since 2002, we mainly focused on synthesis of new phosphorus ligands, asymmetric hydrogenation of heteroaromatic compounds and palladium-catalyzed asymmetric hydrogenation. Significant contribution was made in the Dalian Institute of Chemical Physics. In this chapter, we hope to share our experience and adventure in the development of chiral monophosphite ligands and phosphine-phosphoramidite ligands, asymmetric hydrogenation of heteroaromatic compounds, and the development of new homogeneous palladium catalytic hydrogenation system, which have a wide range of applications in synthesis of chiral compounds.

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Asymmetric Hydrogenation of α‐Keto Phosphonates with Chiral Palladium Catalysts

Cited by 59 publications

References 72 publications

Palladium‐Catalyzed Asymmetric Hydrogenation of Simple Ketimines Using a Brønsted Acid as Activator

Palladium‐Catalyzed Asymmetric Hydrogenation of Simple Ketimines Using a Brønsted Acid as Activator

One‐Pot Two‐Step Synthesis of Optically Active α‐Amino Phosphonates by Palladium‐Catalyzed Hydrogenation/Hydrogenolysis of α‐Hydrazono Phosphonates

Adventure in Asymmetric Hydrogenation: Synthesis of Chiral Phosphorus Ligands and Asymmetric Hydrogenation of Heteroaromatics

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