1132-26-9Relevant articles and documents
SYNTHESIS OF α-SUBSTITUTED α-AMINO ACIDS BY THE ALKYLATION OF 5-OXAZOLINONE DERIVATIVES
Slavinskaya, V. A.,Sile, D. E.,Katkevich, M. Yu.,Korchagova, E. Kh.,Lukevits, E.
, p. 724 - 728 (1994)
Methods have been developed for the alkylation of 5-oxazolinone derivatives in DMF in the presence of K2CO3, KOH, or diisopropylethylamine and a phase transfer catalyst as well as for the preparation of α-methylphenylalanine, α-methylalanine, α-methylalanine, and the methyl ester of N-benzoyl-α-methylalanine.Increasing the initial concentration of the starting 5-oxazolinone in the reaction mixture leads to a sharp drop in the yield of reaction products due to side condensation reactions.The reaction of 2-phenyl-4-benzyl-5-oxazolinonewith ethyl iodide gave a dimer, mamely, 3-(benzoylamino)-3,5-dibenzylpyrrolidine-2,4-dione.
Application of metal reagent to the asymmetric synthesis of α-αamino acids
Hu, Ai-Guo,Zhang, Ling-Yun,Wang, Shan-Wei,Wang, Ji-Tao
, p. 2143 - 2147 (2002)
Using "mix-ligands" type chiral synthons containing metal ions, a,a-amino acids were obtained in "one-pot" reactions in moderate to high yields and ee% values.
Catalytic, asymmetric synthesis of α,α-disubstituted amino acids
Belokon', Yuri N.,Bhave, Devayani,D'Addario, Daniela,Groaz, Elizabetta,Maleev, Viktor,North, Michael,Pertrosyan, Armine
, p. 2045 - 2048 (2003)
Copper(salen) complex 1 has been found to catalyse the asymmetric alkylation of enolates derived from a variety of amino acids. There is a clear relationship between the size of the side chain in the substrate and the enantioselectivity of the process, so that the enantioselectivity decreases in the order alanine>aminobutyric acid>allylglycine>leucine>phenylalanine>valine. A transition state model which accounts for the influence of the size of the side chain on the enantioselectivity of the reactions is presented.
Enantiocatalytic activity of substituted 5-benzyl-2-(pyridine-2-yl) imidazolidine-4-one ligands
Drabina, Pavel,Karel, Sergej,Panov, Illia,Sedlak, Milos
, p. 334 - 339 (2013/04/23)
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.
Lyaseenzymes, Nucleic Acids Encoding Them and Methods For Making and Using Them
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, (2012/07/27)
This invention provides polypeptides having lyase activity, polynucleotides encoding these polypeptides, and meth-°ds of making and using these polynucleotides and polypeptides. In one aspect, the invention is directed to polypeptides having ammonia lyase activity, e.g., phenylalanine ammonia lyase, tyrosine ammonia lyase and/or histidine ammonia lyase activity, including thermostable and thermotolerant activity, and polynucleotides encoding these enzymes, and making and using these polynucleotides and polypeptides. The polypeptides of the invention can be used in a variety of pharmaceutical, agricultural and industrial contexts. X═NO2, Cl, Br, NH2, OH, H, alkyl at one or several o, m, and p positions R═H or alkyl.
Lyase Enzymes, Nucleic Acids Encoding Them and Methods for Making and Using Them
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, (2011/02/25)
This invention provides polypeptides having lyase activity, polynucleotides encoding these polypeptides, and methods of making and using these polynucleotides and polypeptides. In one aspect, the invention is directed to polypeptides having ammonia lyase activity, e.g., phenylalanine ammonia lyase, tyrosine ammonia lyase and/or histidine ammonia lyase activity, including thermostable and thermotolerant activity, and polynucleotides encoding these enzymes, and making and using these polynucleotides and polypeptides. The polypeptides of the invention can be used in a variety of pharmaceutical, agricultural and industrial contexts.
Versatile synthesis of free and N-benzyloxycarbonyl-protected 2,2-disubstituted taurines
Wang, Boyuan,Zhang, Wei,Zhang, Leilei,Du, Da-Ming,Liu, Gang,Xu, Jiaxi
, p. 350 - 355 (2008/09/18)
An effective and versatile method was developed to synthesize N-benzyloxycarbonyl-protected and free 2,2-disubstituted taurines. Several novel 2,2-disubstituted taurines, including aliphatic/aromatic and cyclic/acyclic derivatives, were obtained, which demonstrates the generality of this method. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Asymmetric PTC C-Alkylation Catalyzed by Chiral Derivatives of Tartaric Acid and Aminophenols. Synthesis of (R)- and (S)-α-Methyl Amino Acids
Belokon, Yuri N.,Kochetkov, Konstantin A.,Churkina, Tatiana D.,Ikonnikov, Nikolai S.,Chesnokov, Alexey A.,Larionov, Oleg V.,Singh, Ishwar,Parmar, Virinder S.,Vyskocil, Stepan,Kagan, Henri B.
, p. 7041 - 7048 (2007/10/03)
A new type of efficient chiral catalyst has been elaborated for asymmetric C-alkylation of CH acids under PTC conditions. Sodium alkoxides formed from chiral derivatives of tartaric acid and aminophenols (TADDOL's 2a-e and NOBIN's 3a-h) can be used as chiral catalysts in the enantioselective alkylation, as exemplified by the reaction of Schiffs bases la-e derived from alanine esters and benzaldehydes with active alkyl halides. Acid-catalyzed hydrolysis of the products formed in the reaction afforded (R)-α-methylphenylalanine, (R)-α-naphthylmethylalanine, and (R)-α-allylalanine in 61-93% yields and with ee 69-93%. The procedure could be successfully scaled up to 6 g of substrate 1b. When (S,S)-TADDOL or (R)-NOBIN are used, the (S)-amino acids are formed. A mechanism rationalizing the observed features of the reaction has been suggested.
Asymmetric alkylation catalyzed by chiral alkali metal alkoxides of TADDOL. Synthesis of α-methyl amino acids
Belokon',Kochetkov,Churkina,Ikonnikov,Chesnokov,Larionov,Kagan
, p. 917 - 923 (2007/10/03)
It is shown that sodium alkoxides formed from (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(diphenylmethanol) ((R,R)-TADDOL) and some of its derivatives can be used as chiral catalysts for enantioselective alkylation of Schiff's bases derived from alanine with reactive alkyl halides. Acid hydrolysis of the reaction products affords (R)-α-methytphenyl-alanine, (R)-α-allylalanine, and (R)-α-methylnaphthylalanine in 61-93% yields and with ee 69-94%. When (S,S)-TADDOL is used, the (3)-amino acid is formed. A mechanism explaining the observed features of the reaction is proposed.
γ-Substituted pyrrole-based silyl dienol ethers as α-amino acid enolate equivalents: a versatile entry to racemic α-substituted α-amino acids
Zanardi, Franca,Battistini, Lucia,Rassu, Gloria,Cornia, Mara,Casiraghi, Giovanni
, p. 2471 - 2476 (2007/10/02)
γ-Substituted siloxypyrrole derivatives 5-7 have been synthesized by direct alkylation of N-(tert-butoxycarbonyl)-2-(tert-butyldimethylsiloxy)pyrrole 1.These underwent subsequent alkylation with alkyl halides or aldehydes to produce γ,γ-disubstituted α,β-unsaturated lactam intermediates in good yields.Oxidative cleavage of the C(3)-C(4) bond within the lactam moiety gave rise to a number of α-substituted α-amino acids.These include racemic α-methylphenylalanine 14, α-benzylphenylalanine 15, α-benzylserine 18 and α-methylthreonine 21.
