- 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 0362-0368
(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 0605; 0607; 0609; 0618
(2016/11/17)
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- Synthesis of quaternary α-methyl α-amino acids by asymmetric alkylation of pseudoephenamine alaninamide pivaldimine
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The utility of pseudoephenamine as a chiral auxiliary for the alkylative construction of quaternary α-methyl α-amino acids is demonstrated. The method is notable for the high diastereoselectivities of the alkylation reactions, for its versatility with respect to electrophilic substrate partners, and for its mild hydrolysis conditions, which provide α-amino acids without salt contaminants. Alternatively, α-amino esters can be obtained by direct alcoholysis.
- Hugelshofer, Cedric L.,Mellem, Kevin T.,Myers, Andrew G.
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p. 3134 - 3137
(2013/07/26)
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- Enantiocatalytic activity of substituted 5-benzyl-2-(pyridine-2-yl) imidazolidine-4-one ligands
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Currently, asymmetric synthesis represents one of the main streams of organic synthesis. Although an extensive research has been carried out in this area, the synthesis of chiral compounds with the required enantiomeric purity is still a challenging issue. Herein, we focus on the preparation of new enantioselective catalysts based on pyridine-imidazolidinones. The substituted 5-benzyl-2-(pyridine-2-yl)imidazolidine-4-ones 5-8 were prepared by condensation of chiral amino acid amides (α-methylDOPA and α- methylphenylalanine) with 2-acetylpyridine and pyridine-2-carbaldehyde. The individual isomers of the described ligands 5-8 were separated chromatographically. The copper(II) complexes of these chiral ligands were studied as enantioselective catalysts for the asymmetric Henry reaction of substituted aldehydes with nitromethane or nitroethane. The ligands containing a methyl group at the 2-position of the imidazolidinone ring 6a and 8a exhibit a high degree of enantioselectivity (up to 91% ee). The nitroaldols derived from nitroethane (2-nitropropan-1-ols) were obtained with a comparable enantiomeric purity to derivatives of 2-nitroethanol. This group of ligands represents a new and promising class of enantioselective catalysts, which deserve further attention.
- Drabina, Pavel,Karel, Sergej,Panov, Illia,Sedlak, Milos
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p. 334 - 339
(2013/04/23)
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- Non-enzymatic diastereoselective asymmetric desymmetrization of 2-benzylserinols giving optically active 4-benzyl-4-hydroxymethyl-2- oxazolidinones: Asymmetric syntheses of α-(hydroxymethyl)phenylalanine, N-Boc-α-methylphenylalanine, cericlamine and BIRT-377
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A reaction of (S)-2-benzyl-2-(α-methylbenzyl)amino-1,3-propanediol (S)-4a and 2-chloroethyl chloroformate, and the subsequent addition of DBU gave (4R,αS)-4-benzyl-4-hydroxymethyl-3-(α-methylbenzyl)-2-oxazolidinone (4R)-5a (92% de) via a diastereoselective asymmetric desymmetrization process. Debenzylation of (4R)-5a using trifluoromethanesulfonic acid and anisole in MeNO2 gave (R)-4-benzyl-4-hydroxymethyl-2-oxazolidinone (R)-15a, which was converted into (R)-(α-hydroxymethyl)phenylalanine (7) in two steps. N-Boc-α-methylphenylalanine (8), cericlami0ne (9) and BIRT-377 (10) were also synthesized using these asymmetric desymmetrization and debenzylation.
- Sugiyama, Shigeo,Arai, Satoshi,Ishii, Keitaro
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p. 8033 - 8045
(2012/10/07)
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- Studies on Cyclic Dipeptides, II [1a]. Methylated Modifications of cyclo-[Phe-His]
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Synthesis of seven new cyclic dipeptides and their conformational analysis based on 1HNMR spectra is reported as well as their application as models to elucidate the mechanism of cyclic dipeptide catalysis in enantioselective mandelonitrile formation. Further evidence is presented to support the view that a highly ordered supramolecular complex of dipeptides acts as catalyst.
- Noe,Weigand,Pirker,Liepert
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p. 301 - 316
(2007/10/03)
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- Diastereoselective Alkylation of Sultam-Derived Amino Acid Aldimines Preparation of Cα-Methylated Amino Acids
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Alkylation of Schiff bases 2 derived from 4-chlorobenzaldehyde and sultam-derived amino acids 1 gave crystalline diastereomers 3 which after deprotection and re-crystallization, if necessary, afforded in good yield enantiomerically pure Cα-methylated amin
- Ayoub, Mimoun,Chassaing, Gerard,Loffet, Albert,Lavielle, Solange
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p. 4069 - 4072
(2007/10/02)
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