- Phase-transfer enantioselective monoalkylation of prochiral nickel(ii) complexes catalyzed by 3,3′-bis[hydroxy(diphenyl)methyl]-1,1′- binaphthyl-2,23′-diol (BIMBOL) as a route to α-amino acids
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An achiral nickel complex with a Schiff base derived from glycine was alkylated with alkyl halides under conditions of asymmetric phase-transfer catalysis. The chiral tetraol (R)-BIMBOL was employed as a catalyst. The enantiomeric purity of the alkylation products was up to 88%. Subsequent decomposition of the complexes afforded the corresponding a-amino acids.
- Belokon,Maleev,Samoilichenko,Moskalenko,Hakobyan,Saghyan
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- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE a-AMINO ACID USING CHIRAL METAL COMPLEX COMPRISING AXIALLY CHIRAL N-(2-ACYLARYL)-2-[5,7-DIHYDRO-6H-DIBENZO[c,e]AZEPIN-6-YL] ACETAMIDE COMPOUND AND AMINO ACID
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Objects of the present invention are to provide an industrially applicable method for producing an optically active α-amino acid in high yield and in a highly enantioselective manner, to provide a simple production method of an optically active α,α-disubstituted α-amino acid, and to provide an intermediate useful for the above production methods of an optically active α-amino acid and an optically active α,α-disubstituted α-amino acid. The present invention provides a production method of an optically active α-amino acid or a salt thereof, the production method comprising introducing a substituent into the α carbon in the α-amino acid moiety of a metal complex represented by the following Formula (1): by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction, and releasing an optically pure α-amino acid enantiomer or a salt thereof by acid decomposition of the metal complex.
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Paragraph 0339-0341
(2016/05/10)
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- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE α-AMINO ACID USING CHIRAL METAL COMPLEX COMPRISING AXIALLY CHIRAL N-(2-ACYLARYL)-2-[5,7-DIHYDRO-6H-DIBENZO[c,e]AZEPIN-6-YL]ACETAMIDE COMPOUND AND AMINO ACID
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Objects of the present invention are to provide an industrially applicable method for producing an optically active ±-amino acid in high yield and in a highly enantioselective manner, to provide a simple production method of an optically active ±,±-disubstituted ±-amino acid, and to provide an intermediate useful for the above production methods of an optically active ±-amino acid and an optically active ±,±-disubstituted ±-amino acid. The present invention provides a production method of an optically active ±-amino acid or a salt thereof, the production method comprising introducing a substituent into the ± carbon in the ±-amino acid moiety of a metal complex represented by the following Formula (1): by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction, and releasing an optically pure ±-amino acid enantiomer or a salt thereof by acid decomposition of the metal complex.
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Paragraph 0563; 0564; 0573; 0574
(2016/11/17)
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- Novel preparation of chiral α-amino acids using the Mitsunobu-Tsunoda reaction
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An efficient synthesis of racemic or optically active α-amino acids by modified-Mitsunobu alkylation of a racemic or chiral glycine template from alcohols was developed. Libraries of amino acids were prepared in moderate to good yield with good to high enantioselectivity. This simple method widens the scope for preparation of structurally diverse amino acids.
- Noisier, Anais F. M.,Harris, Craig S.,Brimble, Margaret A.
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supporting information
p. 7744 - 7746
(2013/09/02)
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- Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
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In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
- Maurs, Michele,Acher, Francine,Azerad, Robert
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- Convenient access to glutamic acid side chain homologues compatible with solid phase peptide synthesis
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(Chemical Equation Presented) Preparation of several side chain length variants of glutamic acid is achieved via olefin cross metathesis of allyl glycine derivatives. The products are suitably protected for direct use in Fmoc solid-phase peptide synthesis, as demonstrated by successful synthesis of test sequences.
- Ryan, Shannon J.,Zhang, Yongda,Kennan, Alan J.
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p. 4765 - 4767
(2007/10/03)
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- Asymmetric synthesis with 6-tert-butyl-5-methoxy-6-methyl-3,6-dihydro-2H-1,4-oxazin-2-one as a new chiral glycine equivalent: Preparation of enantiomerically pure α-tertiary and α-quaternary α-amino acids
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The chiral oxazinone 2 has been developed as a new chiral glycine equivalent for the asymmetric synthesis of mono- and disubstituted α-amino acids. It is derived from the α-hydroxycarboxylic acid 1, which serves as a chiral auxiliary, and is easily accessible in enantiomerically pure form by optical resolution of the racemic compound (RS)-1. For alkylation reactions, 2 was deprotonated with sBuLi or phosphazenic base. Subsequent treatment with alkyl halides yielded the monosubstituted compounds 13/14a-c, e, f, (ent)-13d, (ent)-14d, while a second alkylation step, via the corresponding enolates, provided the disubstituted compounds 17/18a-d. Both alkylation steps proceeded with good yields and excellent diastereoselectivities (up to 99% de) and even less reactive electrophiles such as isopropyl iodide could be used. The results obtained in this reaction supported the assumption that the enolate of 2, as well as those of the monosubstituted derivatives of 2, have less tendency to form the aggregates that hamper alkylation reactions with other systems with higher oxygen content. From the major diastereomers of both the mono- and the disubstituted derivatives of 2 the corresponding α-amino acids 33a-c and 34a-d were obtained in high enantiomeric purity by hydrolytic cleavage of the oxazinone ring, accomplished either in two steps with aqueous TFA and aqueous NaOH or in one with either aqueous NaOH or 3 N HBr. Alkylation of the enolate ions of (S)-2 or (R)-2 with epichlorohydrins as bifunctional electrophiles provided the hydroxymethylenecyclopropyl derivatives 21 and 22. Hydrolysis of 21 and 22 afforded the free amino acids 35 and (ent)-35. Reductive amination with aniline after oxidation of 21 and 22 to the corresponding aldehydes 24 and 26 provided the compounds 25 and 27, whereas Mitsunobu treatment of 21 and 22 with 1-phenyl-3-(trifluoroacetyl)urea (28) afforded the urea derivatives 29 and 31. Hydrolysis of these compounds yielded the corresponding 1-aminocylopropanecarboxylic acid derivatives 36/(ent)-36 and (ent)-37. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Koch, Claus-Juergen,Simonyiova, Sona,Pabel, Joerg,Kaertner, Annerose,Polborn, Kurt,Wanner, Klaus Theodor
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p. 1244 - 1263
(2007/10/03)
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- Selective synthesis of either enantiomer of α-amino acids by switching the regiochemistry of the tricyclic iminolactones prepared from a single chiral source
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Preparation of L-α-amino acids was easily accomplished simply by exchanging the position of the lactone group of our recently reported chiral template I from C2 to C3. The new chiral template 7 was prepared in 54% overall yield over five steps from (1R)-(+)-camphor. Alkylation of iminolactone 7 afforded the α-monosubstituted products in good yields and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired L-α-amino acids in good yields and ee with nearly quantitative recovery of chiral auxiliary 4.
- Xu, Peng-Fei,Lu, Ta-Jung
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p. 658 - 661
(2007/10/03)
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- Highly efficient catalytic synthesis of α-amino acids under phase-transfer conditions with a novel catalyst/substrate pair
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A facile and fast enantioselective synthesis of α-amino acids with high ee values was achieved by the asymmetric alkylation of the glycine derivative 1 under phase-transfer conditions with (R)-2-amino-2′-hydrozy-1,1′-binaphthyl (NOBIN; see sceme). The ee value of the amino acid products. This occures as a results of a significant positive nonlinear effect in the alkylation reaction.
- Belokon, Yuri N.,Kochetkov, Konstantin A.,Churkina, Tatiana D.,Ikonnikov, Nikolai S.,Larionov, Oleg V.,Harutyunyan, Syuzanna R.,Vyskocil, Stepan,North, Michael,Kagan, Henri B.
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p. 1948 - 1951
(2007/10/03)
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- The imine (+)-pseudoephedrine glycinamide: A useful reagent for the asymmetric synthesis of (R)-α-amino acids
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The new imine derived from Myers (+)-pseudoephedrine glycinamide can be diastereoselectively alkylated with alkyl halides at room temperature using NaOEt or LiO-tert-Bu as bases under phase transfer conditions. Hydrolysis to the corresponding alkylated products was easily achieved under mild conditions to afford (R)-α-amino acids.
- Guillena, Gabriela,Najera, Carmen
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p. 181 - 183
(2007/10/03)
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- Chiral salen-metal complexes as novel catalysts for the asymmetric synthesis of α-amino acids under phase transfer catalysis conditions
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Chiral salen-metal complexes have been tested as catalysts for the C-alkylation of Schiff's bases of alanine and glycine esters with alkyl bromides under phase-transfer conditions (solid sodium hydroxide, toluene, ambient temperature, 1-10 mol% of the catalyst). The best catalyst, which was derived from a Cu(II) complex of (1R, 2R or 1S,2S)-[N,N′-bis(2′-hydroxybenzylidene)]-1,2-diaminocyclohexane, gave α-amino and α-methyl-α-amino acids with enantiomeric excesses of 70-96%.
- Belokon, Yuri N,North, Michael,Churkina, Tatiana D,Ikonnikov, Nikolai S,Maleev, Victor I
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p. 2491 - 2498
(2007/10/03)
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- 1,5-dimethyl-4-phenylimidazolidin-2-one-derived iminic glycinimides: Useful new reagents for practical asymmetric synthesis of α-amino acids
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New 1,5-dimethyl-4-phenylimidazolidin-2-one-derived acyclic chiral iminic glycine reagents have been prepared and diastereoselectively alkylated with activated alkyl halides and electrophilic olefins in the presence of lithium chloride under (a) strong bases (LHMDS, KOBu(t)) and low temperature (-78 °C,) conditions; (b) solid-liquid phase-transfer catalysis reaction (LiOH, TBAB, -20 °C) conditions, and (c) in the presence of organic bases (DBU, BEMP, TMG, -20 °C). In the case of dielectrophiles C- and N-alkylation takes place to afford heterocyclic derivatives. Hydrolysis of alkylated products has been carried out (a) in two-step procedures with LiOOH or LiOH followed by acidic hydrolysis or Dowex purification, (b) in one single-step under refluxing water to give the corresponding α-amino acid, (c) in the presence of DBU in methanol to provide N-protected α-amino acids methyl esters, or (d) by a protection-hydrolysis procedure to afford N-Boc-protected α-amino acids. The chiral imidazolidinone has generally been recovered in good yield. This methodology has been shown to be useful for the synthesis of acyclic and heterocyclic (S)- and (R)-α-amino acids.
- Guillena,Najera
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p. 7310 - 7322
(2007/10/03)
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- Asymmetric Alkylation of 8-Phenylmenthyl N-glycinate Enolates. Synthesis of D- and L-α-Amino Acids from a Single Chiral Precursor
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The herein described studies on the enolization and subsequent alkylation of the acyclic glycine title ester evidence the involvement of the kinetics of the alkylation step on the stereochemical outcome of the overall process, apart from that of the deprotonation sequence itself.Careful choice of reaction conditions allow for the selective obtention of α-amino acids either of the L- or the D-series without the need of changing the chiral inducer: deprotonation with LDA or t-BuLi followed by reaction with alkyl triflates gives rise to the 2R- α-amino acids, whereas the 2S isomers can be obtained by deprotonation with KO-t-Bu followed by reaction with alkyl halides.
- Alvarez-Ibarra, Carlos,Csaky, Aurelio G.,Maroto, Raquel,Quiroga, M. Luz
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p. 7934 - 7940
(2007/10/03)
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- Asymmetric Induction in Acyclic Radical Reactions: Enantioselective Syntheses of α-Amino Acids via Carbon-Carbon Bond Forming Radical Reactions.
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The derivative of glycine, 8-phenylmenthyl N-Boc-2-bromoglycinate 1 reacted with allyltri-n-butylstannanes via the corresponding radical 2 by the SH2' mechanism to give (2S) allyl amino acid derivatives with high diastereoselectivity.The reaction of 1 with triphenyl(1,2-propadienyl)stannane and triphenyl(2-propynyl)stannane gave the (2S) allenyl and (2S) propargyl amino acid derivatives respectively also with high diastereoselectivity but by a different mechanism.
- Hamon, David P. G.,Massy-Westropp, Ralph A.,Razzino, Pasquale
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p. 4183 - 4194
(2007/10/02)
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- Synthesis of Racemic α-Amino Carboxamides via Lewis Acid-Mediated Reactions of α-Methoxyglycinamide Derivatives with Allylsilanes: Enzymatic Resolution to Optically Active α-Amino Acids
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A short and expedient synthetic route to optically active, saturated and γ,δ-unsaturated α-amino acids is reported.The key step is a BF3*Et2O-mediated reaction of allylsilanes with N-(alkoxycarbonyl)-α-methoxyglycinamides 11-15, leading to the corresponding γ,δ-unsaturated α-aminocarboxamides.The genuine SN1-character of this process with iminium ion 6 as intermediate is proven in the case of the glycine ester 10.Thus, reaction of enzymatically resolved 10 with ?-nucleophiles leads to racemic products.The most useful iminium precursors are the N-methoxyamides 12-14 providing good yields of coupling products.The most convenient N-protective group is the allyloxycarbonyl group.Deprotection proceeds via a Pd(O)-catalyzed transprotection to the corresponding BOC-protected analogues.Four examples of the enzymatic resolution of α-amino carboxamides, by using an L-specific aminopeptidase from Pseudomonas putida, are described in detail.Most notably, secondary N-methoxyamides are good substrates for the enzyme to provide the desired α-amino acids in high optical purity.
- Roos, Eric C.,Mooiweer, Hendrik H.,Hiemstra, Henk,Speckamp, W. Nico,Kaptein, Bernard,et al.
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p. 6769 - 6778
(2007/10/02)
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- Synthesis of (Optically Active) Sulfur-Containing Trifunctional Amino Acids by Radical Addition to (Optically Active) Unsaturated Amino Acids
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Sulfur-based radicals, generated from R-S-H-type precursors (R = alkyl, acyl) with AIBN, smoothly add to α-allylglycines protected at none, one, or both of the amino acid functions (NH2 and/or CO2H).Sulfur-containing trifunctional amino acids were obtained in good to excellent yields (64-100 percent).The solvent used for the reaction is critical.Optimal results were obtained when both the unsaturated amino acid and RSH dissolve completely in the medium (dioxane/water or methanol/water are good solvent systems).The scope of the reaction includes α-substituted α-allylglycine derivative and derivatives as well as β-substituted β-allyl-β-amino alcohols.In the case of optically active α-allylglycine derivatives, radical addition is accompanied by a small amount of racemization, the amount depending on the type of protection and R-S-H.The products are easily optically enriched by crystallization.Addition of sulfur-based radicals to α-allylglycine is believed to be an example of a general method for synthesizing optically active trifunctional amino acids from unsaturated amino acids.
- Broxterman, Quirinus B.,Kaptein, Bernard,Kamphuis, Johan,Schoemaker, Hans E.
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p. 6286 - 6294
(2007/10/02)
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- ASYMMETRIC SYNTHESIS VII: DOUBLE STEREODIFFERENTATION IN ALLYLYTION OF KETIMINES BEARING TWO CHIRAL AUXILIARIES. APPLICATION TO ENANTIOSELECTIVE SYNTHESIS OF α-ALLYLGLYCINE
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A diuble asymmetric induction has been observed in allylation of the imines derived from (+)-camphor, (+)- and (-)-2-hydroxypinan-3-ones with (+)- and (-)-menthyl glycinates.After hydrolysis of the allylated intermediates, (R)- and (S)-α-allylglycines are obtained in 3-90percent optical yields.
- Yaozhong, Jiang,Changyou, Zhou,Huri, Piao
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p. 881 - 888
(2007/10/02)
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- Practical Asymmetric Syntheses of α-Amino Acids through Carbon-Carbon Bond Constructions on Electrophilic Glycine Templates
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The optically active D- and L-erythro-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-ones (3) and D- and L-erythro-4-(tert-butoxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-ones (3) can be efficiently brominated to serve as electrophilic glycine templates for the asymmetric synthesis of amino acids.It was found that coupling to these templates can proceed with either net retention or net inversion of stereochemistry.The final deblocking to the amino acids is accomplished with either dissolving-metal reduction or catalytic hydrogenolysis.The syntheses of β-ethyl aspartic acid, norvaline, allylglycine, alanine, norleucine, homophenylalanine, p-methoxyhomophenylalanine, cyclopentylglycine, and cyclopentenylglycine and a formal synthesis of clavalanine are described.In addition, the direct asymmetric syntheses of N-t-BOC-allylglycine and N-t-BOC-cyclopentenylglycine are described.
- Williams, Robert M.,Sinclair, Peter J.,Zhai, Dongguan,Chen, Daimo
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p. 1547 - 1557
(2007/10/02)
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