- Catalytic asymmetric synthesis of functionalized α,α- disubstituted α-amino acid derivatives from racemic unprotected α-amino acids via in-situ generated azlactones
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Masked and activated highly enantioenriched α,α-disubstituted α-amino acids with an additional adjacent stereocenter were formed by a tandem reaction involving five steps using racemic unprotected amino acid substrates. Key step is the 1,4-addition of in-situ generated azlactones to a broad number of enones. The products of this step-economic route can, e.g., be useful for a divergent and rapid access to biologically interesting unnatural glutamic acid derivatives. Copyright
- Weber, Manuel,Frey, Wolfgang,Peters, Rene
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supporting information; experimental part
p. 1443 - 1449
(2012/07/13)
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- Efficient kinetic resolution of amino acids catalyzed by lipase AS 'Amano' via cleavage of an amide bond
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Herein the efficient kinetic resolution of non-natural alpha-amino acids catalyzed by lipase AS 'Amano' via cleaving the amide bond is reported. The starting materials were the corresponding amino acid amides and the amino acids were generated with ees of up to 99% with E values of >600. These results indicated that the lipase AS 'Amano' could be a powerful amide hydrolase for the kinetic resolution of amino acid starting from the corresponding amino acid amides.
- Wang, Bo,Liu, Yanfeng,Zhang, Dela,Feng, Yuhong,Li, Jiacheng
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p. 1338 - 1342,5
(2020/09/16)
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- Palladium-catalyzed amidocarbonylation improved by recyclable ionic liquids
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Two types of ionic liquids (halide anion ionic liquids and Brensted acidic ionic liquids) were first applied to improve the palladium-catalyzed amidocarbonylation. Both the palladium catalyst and the ionic liquids could be recycled at least five times without significant loss in catalytic activity. Georg Thieme Verlag Stuttgart.
- Zhu, Bingchun,Jiang, Xuanzhen
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p. 2795 - 2798
(2008/02/11)
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- Syngas reactions XIV. Amidocarbonylation as a route to α-amidocarboxylic acids
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The amidocarbonylation of olefin and aldehyde substrates has been applied to the synthesis of a variety of amidocarboxylic acids, including surface active agents (e.g.C14-C16 N-acyl-α-amino acids), specialty surfactants (such as the sarcosinates), intermediates for sweeteners (e.g. aspartame), food additives (e.g. glutamic acid), and certain chelating agents.Homogeneous cobalt and rhodium-based catalysts, modified, for example, with sulfoxide and bidentate phosphine ligands, have been tailored to the synthesis of each individual class of product.Process studies, including examinations of reaction rate, product selectivity, as well as catalyst stability, have been undertaken for N-acetylglycine and amido acid surfactant syntheses.
- Lin, J.J.,Knifton, John F.
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- Racemic Structures of Organic Ammonium Salts of N-Acetyl-DL-2-aminobutyric Acid and N-Acetyl-DL-norvaline and Optical Resolution by Preferential Crystallization of DL-Ammonium Salts
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The racemic structures of the ammonium salts (AM salts) and seven organic ammonium salts of N-acetyl-DL-2-aminobutyric acid (Dl-AcAbu) and N-acetyl-DL-norvaline (DL-AcNva) were studied on the basis of thermodynamic analyses to explore the possibility of optical resolution by preferential crystallization.An empirical equation has been derived from thermodynamic data and melting points of ammonium and organic ammonium salts of N-acyl-DL-amino acids to predict racemic structure around room temperature.The AM salts of DL-AcAbu and -AcNva exist in conglomerate around room temperature.It is possible to resolve optically these DL-AM salts by preferential crystallization in ethanol at 10 deg C, and the succesive preferential crystallization followed by purification gave D- and L-2-aminobutyric acids and -norvalines with optical purities close to 100percent.
- Shiraiwa, Tadashi,Yoshida, Hirokazu,Tsuda, Makoto,Kurokawa, Hidemoto
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p. 947 - 952
(2007/10/02)
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- STUDIES ON HYDROCARBOXYLATION OF N-ACETYLIMINES, ENAMINES AND ALLYLAMINES.
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Treatment of an amide with an aldehyde in the presence of Co2(CO)8/CO/H2 results in N-acyl-α-amino acids. The scope and limitations of this reaction are explored
- Magnus, Philip,Slater, Martin
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p. 2829 - 2832
(2007/10/02)
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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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- Process for production of N-acyl-α-amino acids
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A process for the production of an N-acyl-α-amino acid represented by the general formula STR1 wherein R1, R2, R3 and R4, independently from each other, represent a hydrogen atom, an alkyl or cycloalkyl group which may be substituted, or an aryl or heteroaromatic group selected from the group consisting of furyl, pyrrolyl, pyridinyl, thienyl and indolyl which may be substituted, which comprises reacting an oxirane represented by the general formula STR2 wherein R1 and R2 are as defined above, an amide compound represented by the general formula wherein R3 and R4 are as defined above, and carbon monoxide in the presence of hydrogen, a cobalt-containing catalyst, and a promoter composed of a compound containing a metal selected from Groups I, II, III and IV of the periodic table.
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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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