Recent advances in biaryl-type bisphosphine ligands

Shimizu, Hideo; Nagasaki, Izuru; Saito, Takao

doi:10.1016/j.tet.2005.03.022

Cited by 349 publications

(166 citation statements)

References 216 publications

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“…Ferrocene ligands, such as josiphos (7) and taniaphos (8) ( Table 1, entries 1 and 2), or the P,P-bidentate ligands chiraphos (9), norphos (10), and phanephos (11) entry 7). To our delight, the ligand DTBMsegphos (15), which has a bulky substituted phosphine and a minor dihedral angle, [18] produced a dramatic enhancement in the asymmetric induction, leading to (+)-4 a in 96 % ee (80 % yield). The catalyst loading could be decreased from 10 to 5 mol % with similar reactivity and enantioselectivity (Table 1, entry 10).…”

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confidence: 97%

“…The stereochemical and configurational assignment of (+)-(2R,3R,4S,5R)-4 a was unequivocally established by X-ray diffraction analysis of a recrystallized sample of greater than 99 % ee. [16] With these optimal reaction conditions in hand, we next examined the scope of the 1,3-dipolar cycloaddition with regard to the a-iminoester (Table 2). A rather homogeneous regioselectivity (from 78:22 to 90:10) and high enantioselectivity (80-99 % ee) was observed regardless of the ortho, meta, or para substituents on the aromatic ring, as well as the electron-withdrawing or electron-donating nature of the substituents ( Table 2, entries [1][2][3][4][5][6][7][8].…”

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The Phenylsulfonyl Group as a Temporal Regiochemical Controller in the Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Ylides

2008

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Pyrrolidine derivatives are a significant group of heterocycles which are present in an array of natural and synthetic biologically active products.[1] Furthermore, proline analogues have applications as chiral ligands and as organocatalysts in asymmetric synthesis.[2] This synthetic and biological relevance has encouraged the development of efficient routes for the stereoselective and enantioselective preparation of substituted pyrrolidines. [3] In this context, the metalcatalyzed asymmetric [3+2] cycloaddition of stabilized azomethine ylides with electron-deficient alkenes has emerged as one of the most convergent and atom-economical tools for the enantioselective synthesis of pyrrolidine and proline-type derivatives. [4,5] The regioselectivity in the cycloaddition of stabilized Nmetalated azomethine ylides (usually derived from glycine esters) with unsymmetrically substituted electron-deficient olefins is controlled by electronic effects, leading to pyrrolidine rings, which are substituted at the 2-and 4-positions, as the sole product.[6] However, this excellent regiocontrol hampers the preparation of the regioisomeric pyrrolidine rings with electron-withdrawing substituents at the 2-and 3-positions. This type of structural unit is frequently found in natural, and biologically active compounds. For instance, 2,3-dicarboxylic acid substituted pyrrolidine units are potent and selective inhibitors of glutamate receptors and glutamate transporters, [7] and they have been used in the design of new peptides and constrained peptidomimetics.[8] Taking into account that most methods currently used in the preparation of pyrrolidines with 2,3-dicarboxylic acid substitution are based on multistep approaches from a-amino acid precursors, [9] the development of more convergent synthetic strategies is highly desirable.We have recently reported that unsubstituted vinyl sulfones [10] and bis(sulfonyl)ethylenes [11] are excellent dipolarophiles in the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. Bearing in mind the excellent properties of the sulfonyl group both as a powerful electronwithdrawing group and as an easily removed substituent, [12] we envisaged that the regioselectivity of the catalytic asymmetric reaction of sulfonyl acrylates with azomethine ylides derived from iminoesters could be controlled by the sulfonyl moiety rather than the ester group, [13] and lead to the regioselective and stereoselective formation of 2,3-dicarboxylic acid substituted pyrrolidines (Scheme 1). Herein, we describe the scope of this strategy and its application to the enantioselective synthesis of a variety of 2,3-dicarboxylic ester substituted pyrrolidines and derivatives.First, we carried out the reaction of methyl (E)-3-phenylsulfonylpropenoate and N-benzylideneglycine methyl ester (1 a) under the optimal reaction conditions previously reported by us for the copper-catalyzed 1,3-dipolar cycloaddition of azomethine ylides and bis(sulfonyl)ethylenes. [11] However, under these reaction conditions [[Cu(CH 3 CN) 4 ]...

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The Phenylsulfonyl Group as a Temporal Regiochemical Controller in the Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Ylides

2008

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“…Chiral bisphosphines have proven to be the most successful and widely used ligands for this purpose. 5,6 Among the best catalysts for AH of simple, aromatic prochiral ketones is Noyori's [RuXY{(R)-BINAP}{(R,R)-DPEN}] (1a: X＝Y＝Cl, 1b: X＝H, Y＝BH 4 ; BINAP: 2,2'-bis(diaryl-phosphino)-1,1'-binaphthyl; DPEN: 1,2-diphenylethylenediamine). [7][8][9][10][11][12][13][14][15][16][17][18][19] Here, the high degree of enantioselectivity is considered to result from the cooperative effects of the chiral diphosphane and chiral diamine ligands.…”

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confidence: 99%

Solution Structure and Behavior of Benzophenone‐based Achiral Bisphosphine Ligands in Noyori‐Type Ru(II)‐Catalysts

et al. 2007

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We herein report on solution structural studies of Ru II catalysts (3a, 9) composed of achiral bisphosphine ligands (4, 8) and the enantiopure 1,2-diphenylethylenediamine (DPEN). Complete chiral induction from enantiopure (R,R)-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional (even at 70 ℃) configuration. The coordination of the C＝O moiety in 4 to the cationic Ru II center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity (91% enantiomeric excess) and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the (R,R)-DPEN induces a M-conformation (right-handed) chirality for flexible phosphine ligand 4 in the complex, resulting in a λ,λ-configuration about the Ru II center.

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“…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. [38] On the whole, the ligands of the biphenyl type, namely, (S)-5, Under the optimal reaction conditions, a series of diisopropyl (Z)-[aryl(phenylhydrazono)methyl]-phosphonates (Z)-2c-i was explored to examine the reaction scope. The obtained results presented in Table 3 show that the electronic effect of the substituent in the para-position of the benzene ring exerts only a slight effect on both the stereoselectivity of the process and the yield of the product (entries 1-5).…”

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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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Recent advances in biaryl-type bisphosphine ligands

Cited by 349 publications

References 216 publications

The Phenylsulfonyl Group as a Temporal Regiochemical Controller in the Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Ylides

The Phenylsulfonyl Group as a Temporal Regiochemical Controller in the Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Ylides

Solution Structure and Behavior of Benzophenone‐based Achiral Bisphosphine Ligands in Noyori‐Type Ru(II)‐Catalysts

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

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