Synthesis of a Novel Chiral Binaphthyl Phospholane and Its Application in the Highly Enantioselective Hydrogenation of Enamides

Xiao, Duan; Zhang, Zhaoguo; Zhang, Xumu

doi:10.1021/ol991074m

Cited by 144 publications

(81 citation statements)

References 27 publications

(14 reference statements)

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“…Studies of molecular models suggest that H 8 is situated above an aromatic ring in the (R a )- and (S a )- isomers and should thus be shifted to higher field in these compounds, in accordance with what was observed for (R a )--3. In this compound no coupling was observed between H 8 and H 2 , which suggests that there is restricted rotation of the isopropyl group and a ca. 90°H-C-C-H dihedral angle.…”

Section: Introductionmentioning

confidence: 77%

“…[5] 8,9-Dihydro-7H-dinaphtho[2,1-c:1Ј,2Ј-e]phosphepine (A) derivatives, first prepared by Gladiali [6] and subsequently explored by Steltzer, [7] have recently found numerous applications in asymmetric catalysis. [8] The corresponding stereochemically dynamic biphenyl derivative (B, X = P-R) has, however, been rarely studied or applied in catalytic reactions. [9] We used this flexible unit as well as its nitrogen analogue in the synthesis of ligands with pseudo-C 2 and 108 to the each metal center were obtained upon reaction with [Rh(COD) 2 ] + BF 4 -.…”

Section: Introductionmentioning

confidence: 99%

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Stereochemical Control of Chirally Flexible Phosphepines

Žalubovskis¹,

Fjellander²,

Szabó³

et al. 2006

Eur J Org Chem

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The barriers to interconversion of the two enantiomeric atropisomers of 6‐methoxy‐6,7‐dihydro‐5H‐dibenzo[c,e]phosphepine and that of the diastereomeric forms of 6‐(–)‐menthoxy‐6,7‐dihydro‐3H‐dibenzo[c,e]phosphepine were determined by NMR spectroscopical methods to be 19.3 and 18.5 kcal mol–1, respectively, at 298 K. The ratio of the atropisomers was shown to depend on the group bound to phosphorus. Only complexes with two homochiral ligands bound to the each metal center were obtained upon reaction with [Rh(COD)2]+ BF4–. The Rh complexes catalyzed the hydrogenation of α‐acetamidocinnamate. The major isomer of6‐(–)‐menthoxy‐6,7‐dihydro‐5H‐dibenzo[c,e]phosphepinewas found to exhibit higher activity but to afford a product with lower ee than its diastereomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Stereochemical Control of Chirally Flexible Phosphepines

Žalubovskis¹,

Fjellander²,

Szabó³

et al. 2006

Eur J Org Chem

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“…Because a new chiral center is generated, we decided to perform the reaction in the presence of chiral auxiliaries. We found that BI-NAPHANE [10] provides effective chiral induction (up to 99 % ee) during the conversion of 4 to 5 [Eq. (2)].…”

mentioning

confidence: 99%

Hg(OTf)₂–BINAPHANE‐Catalyzed Enantioselective Anilino Sulfonamide Allyl Alcohol Cyclization

Yamamoto

Namba

et al. 2010

Chemistry A European J

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“…[12] (R or S)-2,2'-Bistriflate-1,1'-binaphthyl (5) was obtained from (R or S)-binaphthol with excess trifluoromethane sulfonic anhydride and pyridine in CH 2 Cl 2 . Kumada-type coupling of bistriflate 5 with methylmagnesium bromide gave (R or S)-2,2'-dimethyl-1,1'-binaphthyl (6) almost in a quantitative yield.…”

mentioning

confidence: 99%

Matching and Mismatching Effects of Hybrid Chiral Biaxial Bisphosphine Ligands in Enantioselective Hydrogenation of Ketoesters

Sun

Zhou

et al. 2009

Chemistry A European J

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Catalytic asymmetric synthesis is a significant component in modern organic chemistry. It has widely been used to produce a number of optically active compounds, from agrochemicals, to pharmaceuticals, to flavors, and fragrances as well as functional materials.[1] One of the most important methods to increase the stereoselectivity of reactions is multiple stereoselectivity (multiple stereodifferentiation, multiple asymmetric induction), when the stereochemical process proceeds under the control of more than one chiral auxiliary.[2] During the last two decades, these double stereoselective strategies have been successfully applied in a variety of reactions, such as Sharpless dihydroxylation, Michael additions, addition to allyl metals, the Reformatsky reaction, the Mukaiyama reaction, photochemical reactions, alkylation, cycloadditions and the synthesis of heteroatom compounds.[2] In contrast, catalytic systems with multiple stereogenic axial elements in chiral ligands are much less explored in transition metal catalyzed asymmetric hydrogenations. The multiple chiral elements in ligands may be situated favorably ("matched") or unfavorably ("mismatched") for stereocontrol when the catalyst interacts with a prochiral substrate. Ultimately, the matched cases may lead to dramatically higher asymmetric induction in the products, whereas the mismatched cases often result in significantly lower selectivity in hydrogenation reactions.[3] Syntheses of these molecules have facilitated a preliminary study of matching and mismatching effects, relating backbone chirality and phosphorus-based chirality with the performance of these ligands in asymmetric catalysis. The most notable achievements of catalytic systems with double asymmetric induction exist in hydrogenation chemistry, focusing primarily on rhodium or ruthenium with bidentate phosphine ligands, [4] in particular, modifications of DIOP, [5] BINAP, [6] dialkylphospholane bis(phospholane) ligands, [7] and many others.[8] As reported, configurational changes in ligands brought by introducing additional chirality are generally unpredictable. There are no reliable predictive models to explain the structural subtleties of catalysts with multiple chiral elements that lead to dramatic changes in stereoselectivities. [9] As part of our continued interest in the synthesis and use of new chiral bisphosphine ligands in asymmetric catalysis, we have developed a novel class of conformationally rigid C n -TunePhos (n = 1-6) by introducing a bridge with variable length to link the chiral atropisometic biaryl groups.[10] This family of TunePhos ligands has proven to be highly efficient in a variety of asymmetric reactions.[11] We envision that changes of relatively flexible alkyl linker in the C n -TunePhos family with an aromatic group or a bulky chiral bridge may enhance the rigidity and steric hindrance of the structure. Consequently, unique steric or electronic effects and good chiral discrimination could be expected. Herein we report a convenient strategy for the synthesis of ...

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Synthesis of a Novel Chiral Binaphthyl Phospholane and Its Application in the Highly Enantioselective Hydrogenation of Enamides

Cited by 144 publications

References 27 publications

Stereochemical Control of Chirally Flexible Phosphepines

Stereochemical Control of Chirally Flexible Phosphepines

Hg(OTf)₂–BINAPHANE‐Catalyzed Enantioselective Anilino Sulfonamide Allyl Alcohol Cyclization

Matching and Mismatching Effects of Hybrid Chiral Biaxial Bisphosphine Ligands in Enantioselective Hydrogenation of Ketoesters

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Synthesis of a Novel Chiral Binaphthyl Phospholane and Its Application in the Highly Enantioselective Hydrogenation of Enamides

Cited by 144 publications

References 27 publications

Stereochemical Control of Chirally Flexible Phosphepines

Stereochemical Control of Chirally Flexible Phosphepines

Hg(OTf)2–BINAPHANE‐Catalyzed Enantioselective Anilino Sulfonamide Allyl Alcohol Cyclization

Matching and Mismatching Effects of Hybrid Chiral Biaxial Bisphosphine Ligands in Enantioselective Hydrogenation of Ketoesters

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Product

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Hg(OTf)₂–BINAPHANE‐Catalyzed Enantioselective Anilino Sulfonamide Allyl Alcohol Cyclization