- Nickel-Catalyzed Multicomponent Coupling: Synthesis of α-Chiral Ketones by Reductive Hydrocarbonylation of Alkenes
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A nickel-catalyzed, multicomponent regio- and enantioselective coupling via sequential hydroformylation and carbonylation from readily available starting materials has been developed. This modular multicomponent hydrofunctionalization strategy enables the straightforward reductive hydrocarbonylation of a broad range of unactivated alkenes to produce a wide variety of unsymmetrical dialkyl ketones bearing a functionalized α-stereocenter, including enantioenriched chiral α-aryl ketones and α-amino ketones. It uses chiral bisoxazoline as a ligand, silane as a reductant, chloroformate as a safe CO source, and a racemic secondary benzyl chloride or an N-hydroxyphthalimide (NHP) ester of a protected α-amino acid as the alkylation reagent. The benign nature of this process renders this method suitable for late-stage functionalization of complex molecules.
- Chen, Jian,Zhu, Shaolin
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supporting information
p. 14089 - 14096
(2021/09/13)
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- A Facile Approach to the Synthesis of Benzothiazoles from N-Protected Amino Acids
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Abstract: –A simple trituration method for the synthesis of 2-substituted benzothiazoles derived from N-protected amino acids and 2-aminothiophenol using molecular iodine as a mild Lewis acid catalyst has been proposed. The reaction occurs in one step for 20–25 min in solve-free conditions and provides the target products in excellent yields.
- Arfan, M.,Fatima, T.,Mannan, A.,Tahira, A.
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p. 292 - 297
(2020/04/21)
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- Asymmetric construction of dihydrobenzofuran-2,5-dione derivatives via desymmetrization of p-quinols with azlactones
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The desymmetrization of p-quinols through a chiral bisguanidinium hemisalt catalyzed enantioselective Michael addition/lactonization cascade reaction with azlactones was reported. 3-Amino-benzofuran-2,5-diones containing a chiral amino acid residue were achieved with up to 99% ee and >19?:?1 dr. An exploration of the structure of the catalyst bisguanidinium was undertaken, revealing a bifunctional catalytic model.
- Xie, Lihua,Dong, Shunxi,Zhang, Qian,Feng, Xiaoming,Liu, Xiaohua
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supporting information
p. 87 - 90
(2019/01/03)
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- Reactivity of α-Amino Acids in the Reaction with Esters in Aqueous–1,4-Dioxane Media
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The kinetics of the reaction of a series of α-amino acids with 4-nitrophenyl acetate, 4-nitrophenyl benzoate, and 2,4,6-trinitrophenyl benzoate in aqueous 1,4-dioxane medium has been studied. Kinetics of the reactions involving 4-nitrophenyl acetate and 2,4,6-trinitrophenyl benzoate has complied with the Br?nsted dependence and revealed linear correlation between rate constant logarithm and the energy difference of the frontier orbitals of α-amino acids anions.
- Kochetova,Kustova,Kuritsyn
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- Formation of Non-Natural α,α-Disubstituted Amino Esters via Catalytic Michael Addition
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The enolate monoanion of amino esters is explored, and the first catalytic Michael addition of α-amino esters is demonstrated. These studies indicate that the acidity of the αC-H is the primary factor determining reactivity. Thus, polyfluorophenylglycine amino esters yield novel α-amino esters in the presence of a catalytic amount of a guanidine-derived base and Michael acceptors. Reactivity requires an acidic N-H, which is accomplished using common protecting groups such as N-Bz, N-Boc, and N-Cbz. Calculations and labeling experiments provide insight into the governing principles in which a key C-to-N proton transfer occurs, resulting in an expansion of the scope to include a number of natural amino esters. The study culminates with a late-stage functionalization of peptidic γ-secretase inhibitor, DAPT.
- Teegardin, Kip A.,Gotcher, Lacey,Weaver, Jimmie D.
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supporting information
p. 7239 - 7244
(2018/11/25)
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- Polyfluoroarylation of oxazolones: Access to non-natural fluorinated amino acids
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Herein, conditions are provided for the formation and use of the oxazolone enolate for the nucleophilic substitution of highly fluorinated (hetero)arenes, which after unmasking yield highly fluorinated non-natural amino acids and derivatives. In addition, the properties and chemical behavior of this new class of amino acids are explored. The utility is demonstrated in the one pot synthesis of medicinally relevant 2-aminohydantoins.
- Teegardin, Kip A.,Weaver, Jimmie D.
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supporting information
p. 4771 - 4774
(2017/07/06)
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- Enantioselective construction of tetrasubstituted stereogenic carbons through bronsted base catalyzed michael reactions: α′-hydroxy enones as key enoate equivalent
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Catalytic and asymmetric Michael reactions constitute very powerful tools for the construction of new C-C bonds in synthesis, but most of the reports claiming high selectivity are limited to some specific combinations of nucleophile/electrophile compound types, and only few successful methods deal with the generation of all-carbon quaternary stereocenters. A contribution to solve this gap is presented here based on chiral bifunctional Bronsted base (BB) catalysis and the use of α′-oxy enones as enabling Michael acceptors with ambivalent H-bond acceptor/donor character, a yet unreported design element for bidentate enoate equivalents. It is found that the Michael addition of a range of enolizable carbonyl compounds that have previously demonstrated challenging (i.e., α-substituted 2-oxindoles, cyanoesters, oxazolones, thiazolones, and azlactones) to α′-oxy enones can afford the corresponding tetrasubstituted carbon stereocenters in high diastereo- and enantioselectivity in the presence of standard BB catalysts. Experiments show that the α′-oxy ketone moiety plays a key role in the above realizations, as parallel reactions under identical conditions but using the parent α,β-unsaturated ketones or esters instead proceed sluggish and/or with poor stereoselectivity. A series of trivial chemical manipulations of the ketol moiety in adducts can produce the corresponding carboxy, aldehyde, and ketone compounds under very mild conditions, giving access to a variety of enantioenriched densely functionalized building blocks containing a fully substituted carbon stereocenter. A computational investigation to rationalize the mode of substrate activation and the reaction stereochemistry is also provided, and the proposed models are compared with related systems in the literature.
- Badiola, Eider,Fiser, Bla,Gmez-Bengoa, Enrique,Mielgo, Antonia,Olaizola, Iurre,Urruzuno, Iaki,Garca, Jess M.,Odriozola, Jos M.,Razkin, Jess,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 17869 - 17881
(2015/02/19)
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- Peptide-catalyzed conversion of racemic oxazol-5(4 H)-ones into enantiomerically enriched α-amino acid derivatives
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We report the development and optimization of a tetrapeptide that catalyzes the methanolytic dynamic kinetic resolution of oxazol-5(4H)-ones (azlactones) with high levels of enantioinduction. Oxazolones possessing benzylic-type substituents were found to perform better than others, providing methyl ester products in 88:12 to 98:2 er. The mechanism of this peptide-catalyzed process was investigated through truncation studies and competition experiments. High-field NOESY analysis was performed to elucidate the solution-phase structure of the peptide, and we present a plausible model for catalysis.
- Metrano, Anthony J.,Miller, Scott J.
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p. 1542 - 1554
(2014/03/21)
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- Organocatalyzed asymmetric 1,4-addition of azlactones to α,β-unsaturated trichloromethyl ketones: Synthesis of α,α-disubstituted α-amino acid derivatives
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The first asymmetric 1,4-addition of azlactones to α,β-unsaturated trichloromethyl ketones catalyzed by cinchona alkaloid derived bifunctional thiourea catalysts was developed. A series of α,α-disubstituted α-amino acid derivatives bearing a quaternary stereocenter at the α-position were obtained in high yields with excellent diastereo- and enantioselectivities (up to -20:1 dr and 99% ee). In addition, the trichloromethyl moiety in these adducts was identified as a good leaving group.
- Zhang, Jinlong,Liu, Xihong,Wu, Chongyang,Zhang, Panpan,Chen, Jianbo,Wang, Rui
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supporting information
p. 7104 - 7108
(2015/01/16)
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- PROLINAMIDE DERIVATIVE AS THROMBIN INHIBITOR, PREPARATION METHOD AND APPLICATION THEREOF
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Provided are a compound of formula (I), pharmaceutically acceptable salts thereof, preparation methods and applications thereof for inhibiting thrombin, and applications in the treatment and prevention of thrombin-mediated and thrombin-related diseases.
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Paragraph 0035; 0075
(2013/09/26)
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- PROLINAMIADE DERIVATIVES AS THROMBIN INHIBITOR, PREPRARATION METHOD AND APPLICATION THEREOF
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Provided are a compound of formula (I), pharmaceutically acceptable salts thereof, preparation methods and applications thereof for inhibiting thrombin, and applications in the treatment and prevention of thrombin-mediated and thrombin-related diseases.
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Page/Page column
(2013/11/19)
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- Polyclonal antibodies: A cheap and efficient tool for screening of enantioselective catalysts
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Enantioselective polyclonal antibodies have been produced and characterized to develop a high-throughput screening method for lipase activity fingerprinting, with a view to the enantioselective hydrolysis of azlactones.
- MacOvei, Cristian,Vicennati, Paola,Quinton, Julia,Nevers, Marie-Claire,Volland, Herve,Creminon, Christophe,Taran, Frederic
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supporting information; experimental part
p. 4411 - 4413
(2012/05/20)
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- Asymmetric synthesis of α- And β-amino acids by diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl) imines
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The diastereoselective addition of triorganozincates to (R)-N-(tert-butanesulfinyl)imines has been used as a key step to achieve the synthesis of highly enantiomerically enriched N-protected α- and β-amino acids. Desulfinylation of the addition products followed by benzoylation of the nitrogen atom of the obtained primary amines and oxidation of one of the substituents on the carbon atom connected to the nitrogen complete the sequence. Using the same configuration in the sulfinyl chiral auxiliary, α-amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α- Disubstituted α-amino esters with high enantiomeric purity can also be prepared when α-imino esters are the starting substrates.
- Almansa, Raquel,Collados, Juan F.,Guijarro, David,Yus, Miguel
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experimental part
p. 1421 - 1431
(2010/11/02)
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- Application of the addition of triorganozincates to N-(tert-butanesulfinyl)imines to the enantioselective synthesis of α-amino acids
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Highly enantiomerically enriched N-protected α-amino acids can be easily prepared from optically pure N-(tert-butanesulfinyl)imines by a four-step sequence involving: diastereoselective addition of a triorganozincate to the imine, removal of the sulfinyl group, benzoylation of the nitrogen atom of the obtained primary amine and oxidation of one of the substituents on the carbon atom α to the nitrogen. Using the same configuration in the sulfinyl chiral auxiliary, amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α-Disubstituted α-amino esters with high optical purity can also be prepared by the diastereoselective addition of trialkylzincates to α-imino esters.
- Almansa, Raquel,Guijarro, David,Yus, Miguel
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scheme or table
p. 4188 - 4190
(2009/12/01)
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- Combining Magnetic Resonance Spectroscopies, Mass Spectrometry, and Molecular Dynamics: Investigation of Chiral Recognition by 2,6-di-O-Methyl-β-cyclodextrin
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EPR spectroscopy has been employed to investigate the formation of complexes between heptakis-(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) and different enantiomeric pairs of chiral nitroxides of general structure PhCH2N(O·)CH(R)R′. Accurate equilibrium measurements of the concentrations of free and included radicals afforded the binding constant values for these nitroxides. The relationship between the stereochemistry of the DM-β-CD complexes and the thermodynamics of complexation was elucidated by correlating EPR data with 1H-1H NOE measurements carried out on the complexes between DM-β-CD and the structurally related amine precursors of nitroxides. NOE data suggested that inclusion of the stereogenic center in the DM-β-CD cavity occurs only when the R substituent linked to the chiral carbon contains an aromatic ring. For these types of complexes, molecular dynamics simulation indicated that the depth of penetration of the stereogenic center into the cyclodextrin cavity is determined by the nature of the second substituent (R′) at the asymmetric carbon and is responsible for the observed chiral selectivity. Analysis of mass spectra showed that, for the presently investigated amines, electrostatic external adducts of CDs with protonated amines are detected by ESI-MS.
- Franchi, Paola,Lucarini, Marco,Mezzina, Elisabetta,Pedulli, Gian Franco
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p. 4343 - 4354
(2007/10/03)
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- Beauveria bassiana ATCC 7159 contains an L-specific α-amino acid benzamidase
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Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield.
- Holland, Herbert L.,Andreana, Peter R.,Salehzadeh-Asl, Reza,Van Vliet, Aaron,Ihasz, Nancy J.,Brown, Frances M.
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p. 667 - 672
(2007/10/03)
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- Inclusion complexes of N-benzoyl-D-leucine and N-benzoyl-L-leucine with β-cyclodextrin by Raman spectroscopy
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We report what is believed to be the first detection of chiral recognition in the inclusion complexes of cyclodextrins by Raman spectroscopy. The spectra of inclusion complexes of N-benzoyl-D-leucine or N-benzoyl-L-leucine with β-cyclodextrin were recorded in the 1500-1800 and 3000-3150 cm-1 regions. These chiral molecules were chosen to provide group frequencies (NH2(+) and benzoyl C=O) near the chiral center of the guest as well as COO- and phenyl CH for probing the guest molecule without spectral interference from the vibrational bands of the cyclodextrin host. Frequency shifts and intensity decreases were observed for some Raman bands of N-benzoyl-leucines upon inclusion in the cyclodextrin cavity. In the Raman spectra of the inclusion complex, the frequency shifts were greater for N-benzoyl-D-leucine than for N-benzoyl-L-leucine.
- Spivey, Robin,Swofford, Robert L.
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p. 435 - 438
(2007/10/03)
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- Palladium-catalyzed amidocarbonylation - A new, efficient synthesis of N-acyl amino acids
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For the first time palladium catalysts have been used successfully for the amidocarbonylation reaction. The activity of the cobalt catalysts that were used exclusively beforehand has now been exceeded by an order of magnitude, and the reaction can be performed under far milder conditions. Palladium-catalyzed amidocarbonylation reactions can now be used for the synthesis of a much wider range of N-acyl amino acids.
- Beller,Eckert,Vollmuller,Bogdanovic,Geissler
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p. 1494 - 1496
(2007/10/03)
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- Reactivity of the Amino Groups of α-Amino Acids and Dipeptides in Reaction with Benzoyl Chloride in a Dioxane-Water Solvent
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The kinetic characteristics (rate constants, activation energies, and entropies of activation) for the reaction of a series of α-amino acids and dipeptides with benzoyl chloride in aqueous dioxane are presented.The amino group in the investigated α-amino acids has high reactivity 4 liter/mole*sec>; the dipeptides have lower reactivity 3 liter/mole*sec>.
- Kuritsyn, L. V.,Kalinina, N. V.
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p. 767 - 770
(2007/10/02)
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- CHEMO-ENZYMATIC ASYMMETRIC SYNTHESIS OF AMINO ACIDS. ENANTIOSELECTIVE HYDROLYSES OF 2-PHENYL-OXAZOLIN-5-ONES.
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Porcine pancreatic lipase and the lipase of Aspergillus niger catalyze the enantioselective hydrolysis of a series of 4-substituted-2-phenyl-oxazolin-5-ones to yield optically active (S)- and (R)-N-benzoyl amino acids respectively.
- Gu, Rui-Lin,Lee, Ik-Soo,Sih, Charles J.
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p. 1953 - 1956
(2007/10/02)
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- Composition containing a penem or carbapenem antibiotic and the use of the same
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially.
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- Composition containing a penem or carbapenem antibiotic
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
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- NEW SYNTHETIC ROUTE TO N-ACYL-α-AMINO ACIDS VIA AMIDOCARBONYLATION BY MEANS OF HOMOGENEOUS BINARY CATALYST SYSTEMS
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New catalytic processes which lead to the formation of N-acyl-α-amino acids promoted by homogeneous binary systems are described: (a) the isomerization-amidocarbonylation of allylic alcohols catalyzed by transition metal binary systems, e.g., Co-Rh, Co-Pd, Co-Fe, giving various aliphatic N-acyl-α-amino acids; (b) the isomerization-amidocarbonylation of oxiranes catalyzed by cobalt-Lewis acid systems giving N-acyl-α-amino acids; The process is extremely effective for the synthesis of N-acetylphenylalanine from styrene oxide and (c) the hydroformylation-amidocarbonylation of trifluoropropene catalyzed by cobalt-rhodium binary system giving N-acetyltrifluorovaline in excellent regioselectivity and yield.Possible mechanisms for these new processes are discussed.
- Hirai, Kenji,Fujita, Makoto,Fuchikami, Takamasa
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p. 203 - 214
(2007/10/02)
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- DIRECT CONVERSION OF ALLYLIC ALCOHOLS INTO N-ACYL-α-AMINO ACIDS BY CATALYTIC AMIDOCARBONYLATION BY MEANS OF HOMOGENEOUS BINARY SYSTEMS
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N-Acyl-α-amino acids are synthesized by the amidocarbonylation of allylic alcohols catalyzed by homogeneous binary systems which consist of cobalt carbonyl and rhodium (or iron or palladium) complexes.
- Hirai, Kenji,Takahashi, Yoshitaka,Ojima, Iwao
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p. 2491 - 2494
(2007/10/02)
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- Chiral Recognition in Catalytic Hydrogenation of α-Acylaminoacrylic Acids by Cationic Rhodium(I) Complexes of Chiral Aminophosphines Derived from (R,R)-1,2-Cyclohexanediamine or (R)-1,2-Propanediamine
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Four chiral diphosphines, (R,R)-1,2-biscyclohexane, (R,R)-1,2-bis-cyclohexane, (R)-1,2-bispropane, and (R)-1,2-bispropane have been prepared from the corresponding optically active diamines.The cationic 1,5-cyclooctadiene rhodium(I) complexes with these diphosphines act as effective homogeneous catalysts for the stereoselective hydrogenation of α-acylaminoacrylic acids.The optical yields and the absolute configurations of the products depend on the kind of diphosphine ligands.The (R,R)-1,2-biscyclohexane complex catalyst yields N-benzoyl-(S)-leucine, N-benzoyl-(S)-phenylalanine, and N-acetyl-(S)-phenylalanine in 94, 92, and 89percent e.e., respectively.The other three catalysts are less effective (6-74percent e.e.).The aminophosphine complexes with methyl groups on the nitrogen atoms always give (S)-amino acids, those with no methyl group (R)-amino acids.Such a difference in the chiral recognition has been discussed on the basis of circular dichroism spectra and Dreiding molecular models of the rhodium (I) complexes.
- Kashiwabara, Kazuo,Hanaki, Kazuhiro,Fujita, Junnosuke
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p. 2275 - 2280
(2007/10/02)
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