- Preparation method of chiral alpha-amino acid
-
The invention discloses a preparation method of chiral alpha-amino acid. Initial raw materials comprising aldehyde and N-acryl substituted glycine undergo Erlenmeyer-Plochl cyclization, hydrolysis or alcoholysis, asymmetric catalytic hydrogenation and acid hydrolysis to obtain the chiral alpha-amino acid compound. The method adopting the above synthesis route has the advantages of mild reaction conditions, simple technological operation, safe and stable production, realization of high yield, good chemical purity and good optical purity of the above obtained product, wide application range, and suitableness for industrial production.
- -
-
Paragraph 0063; 0064; 0065
(2016/10/08)
-
- An asymmetric synthesis of Levetiracetam
-
An asymmetric synthesis of (S)-levetiracetam has been developed through application of a Strecker reaction using [(1S)- 1-(4-methoxyphenyl)ethyl]amine hydrochloride as a chiral auxiliary. Addition of propanaldehyde to a solution of sodium cyanide and [(1S)-1-(4-methoxyphenyl)ethyl]amine hydrochloride in the mixture of methanol and water at 25-30°C afforded diastereomerically pure 2-[2-(4-methoxyphenyl)-(S)-methylethyl-amino]-( S )-butyronitrile hydrochloride compound 4 . In this reaction cyanide group attack at less hindered side that is re-face of the imine intermediate gave the diastereomerically pure nitrile 4. Which upon hydrolysis in the presence of 6 M aqueous hydrochloride solution obtained enantiomerically pure (S )-2- aminobutyric acid hydrochloride 5, is a key intermediate for the (S)-levetiracetam. This intermediate further react with SOCl2 in presence of methanol formed S-2-amino methyl butyrate as in situ intermediate which on further ammonalysis in the presence of methnaolic ammonia as a solvent under ammonia pressure provided S-2-amino butyramide hydrochloride 6 which further condensed with 4-chlorobutyryl chloride 7 and followed by cyclization in the presence of potassium hydroxide, dichloromethane solvent used catalytic amount of tetra butyl ammonium bromide afforded crude (S)-levetiracetam 1, further recrystalization in the presence of ethyl acetate obtained pure (S)-levetiracetam 1.
- Raju, Veeramalla,Somaiah, Sripathi,Sashikanth, Suthrapu,Laxminarayan, Eppakayala,Mukkanti, Kagga
-
p. 1218 - 1221
(2014/12/10)
-
- PREPARATION OF (S)-2-AMINOBUTYRIC ACID
-
Processes for the preparation of (S)-2-aminobutyric acid, embodiments including selective hydrolysis of racemic N-protected-2-aminobutyric acid using an acylase enzyme, such as one derived from Thermococcus litorolis or Aspergillus melleus.
- -
-
Page/Page column 8
(2010/04/03)
-
- Conjugate additions of organocuprates to a 3-methylene-6-isopropyldiketopiperazine acceptor for the asymmetric synthesis of homochiral α-amino acids
-
Addition of a range of organocuprates to (S)-N,N′-bis(p-methoxybenzyl)-3-methylene-6-isopropylpiperazine-2, 5-dione 8 affords cis-3-isopropyl-6-alkyldiketopiperazines in excellent yield and >95% de. Subsequent deprotection and hydrolysis of these cis-3-isopropyl-6-alkyldiketopiperazines affords homochiral (S)-α-amino acids in excellent yield.
- Bull,Davies,Garner,O'Shea
-
p. 3281 - 3287
(2007/10/03)
-
- ENANTIOSELECTIVE SYNTHESES OF α-AMINO ACIDS FROM 10-SULFONAMIDO-ISOBORNYL ESTERS AND DI-t-BUTYL AZODICARBOXYLATE
-
Successive treatment of chiral esters 7 with LDA/Me3SiCl and di-t-butyl azodicarboxylate/TiCl4 and Ti(OiPr)4 gave N,N-di-t-butoxycarbonylhydrazinoesters 11 which on deacylation, hydrogenolysis, transesterification and acidic hydrolysis furnished (2S)-α-amino acid hydrochlorides 13 in good overall yields, high enantiomeric purity and with efficient recovery of the alcohol auxiliary 4.Experimental evidence for the configuration and conformation of the intermediate O-silyl ketene acetals 1 is provided.
- Oppolzer, Wolfgang,Moretti, Robert
-
p. 5541 - 5552
(2007/10/02)
-
- Enantioselective Synthesis of α-Amino Acids from 10-(Aminosulfonyl)-2-bornyl Esters and Di(tert-butyl) Azodicarboxylate
-
Successive treatment of chiral esters 1 with LiN(i-Pr)2/Me3SiCl and di(tert-butyl) azodicarboxylate/TiCl4/Ti(i-PrO)4 gave N,N'-dihydrazino esters 9 which on deacylation, hydrogenolysis, transesterification, and acidic hydrolysis furnished (2S)-α-amino acids 6 in high enantiomeric purity with efficient recovery of the auxiliary alcohol 7.
- Oppolzer, Wolfgang,Moretti, Robert
-
p. 1923 - 1926
(2007/10/02)
-