13893-46-4Relevant academic research and scientific papers
High-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid
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, (2018/09/13)
The invention discloses a high-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid. The high-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid is characterized by comprising the following steps: step one, reacting S-tert-butanesulfinyl amide or R-tert-butanesulfinyl amide, R-beta substituted ethyl pyruvate and tetraethyl titanate in atetrahydrofuran solvent to obtain a compound C; step two, reacting the compound C with alkyl substituted magnesium bromide under the catalyzing effect of zinc dimethyl in tetrahydrofuran to obtain acompound E; step three, reacting the compound E under the effect of ammonium chloride and anhydrous hydrogen chloride to obtain a compound F; and step four, hydrolyzing the compound F in an ethanol aqueous solution of sodium hydroxide to obtain hydrochloride of a compound G, and carrying out ion exchange to obtain the compound G. The chiral selective reaction is greatly improved, and the method issimple in process, uses cheap and easily obtained raw materials, is simple and convenient to operate, is quite suitable for industrial mass production, and has quite extensive industrial applicationprospect and market value.
Chemo-Enzymic Synthesis of Optically Active α,α-Disubstituted α-Amino Acids
Liu, Weiguo,Ray, Paul,Benezra, Steven A.
, p. 553 - 560 (2007/10/02)
A series of α,α-disubstituted α-amino esters was chemically synthesized and then resolved through enantioselective hydrolysis catalysed by a new enzyme isolated from crude Humicola langinosa lipase.This enzyme only accepts free amino esters as substrates with neither lipase activity toward olive oil nor esterase activity toward o-nitrophenyl butyrate.It is unique in that it successfully catalyses the resolution of amino esters with two large α-alkyl groups including aliphatic, aromatic and cyclic amino esters.Examples of resolutions where the alkyl groups differ in size by as little as a single carbon atom have been demonstrated.For determination of absolute configuration, some of the optically active α,α-disubstituted amino acids were also prepared through Schoellkopf's asymmetric synthesis and the structures were verified by X-ray crystallography.A model depicting the substrate binding site of the enzyme is proposed.
Stereoselective Alkylation of Dianions derived from Chiral Half-Esters of Monosubstituted Malonic Acids: Asymmetric Synthesis of α-Alkyl α-Amino Acids and Key Synthetic Intermediates for Hunteria and Aspidosperma Indole Alkaloids
Ihara, Masataka,Takahashi, Masanobu,Taniguchi, Nobuaki,Yasui, Ken,Niitsuma, Hiroko,Fukumoto, Keiichiro
, p. 525 - 535 (2007/10/02)
Substitution of the chiral half-esters of monosubstituted malonic acids with halides leads to the formations of mixtures of the diastereomeric alkyl- or benzyl-malonic half-esters.The (R)-isomers (13A and 15A-22A) were obtained from the phenylmenthyl half-ester 14 of methylmalonic acid in high diastereoisomeric excess.The same stereoisomers were also produced by reaction of the half-esters 9, 23 and 24 with methyl iodide.Their absolute configurations were determined by transforming the major products into the known α-alkyl α-amino acid derivatives 30, 33 and 35.The major product 43, prepared by allylation of the half-ester 9, was converted into two lactones 41 and 42, key intermediates for synthesis of indole alkaloids of the Hunteria and Aspidosperma types.The mechanism of the above alkylation is discussed.
Enantioselective Construction of a Quaternary Asymmetric Carbon Center: A Versatile Synthesis of α-Alkyl α-Amino Acids
Ihara, Masataka,Takahashi, Masanobu,Niitsuma, Hiroko,Taniguchi, Nobuaki,Yasui, Ken,Fukumoto, Keiichiro
, p. 5413 - 5415 (2007/10/02)
The enantioselective construction of a quaternary asymmetric carbon center was developed through reaction of the dianions derived from the chiral half esters of monosubstituted malonic acids with 2 molar equi of LDA and alkyl halides.Alkylation in the reverse sequence preferentially gave the same diastereomer.The alkylated half esters were transformed into α-alkyl α-amino acids.
