89836-92-0

Upstream product

• 123052-90-4 tert-butyl (2S,5S)-2-(tert-butyl)-3-methyl-5-(2-methylpropyl)-4-oxo-1-imidazolidinecarboxylate 
• 123052-93-7 tert-butyl (2S,5R)-2-(tert-butyl)-5-deuterio-3-methyl-5-(2-methylpropyl)-4-oxo-1-imidazolidinecarboxylate 
• 4502-00-5 sodium 4-methyl-2-oxovalerate 
• 61-90-5 L-leucine 
• 282729-31-1 (R)-Z-2-[2H₁]-Leu 
• 282726-23-2 (R,S)-2-[2H₁]-Leu 

Relevant academic research and scientific papers

Simple and efficient preparation of (R)- and (S)-enantiomers of α-carbon deuterium-labelled α-amino acids

A procedure for the synthesis of (R)- and (S)-enantiomers of α-carbon deuterium-labelled α-amino acids, exemplified for (R)- and (S)-[2-2H1]-Leu is described. Starting from the respective (S)- or (R)-enantiomer or from the racemic mixture of an α-amino acid the selective proton exchange at the α-carbon is carried out by racemization via a Schiff base in monodeuterated acetic acid as solvent which serves as deuterium source. After N-protection the racemic mixture is liquid chromatographically separated into the individual (R)- and (S)-enantiomers on preparative scale employing a chiral anion exchanger based on carbamoylated quinine as chiral selector. After deprotection the enantiomerically pure products can be obtained in good yields.

PREPARATION OF α-DEUTERATED L-AMINO ACIDS USING E. coli CELLS CONTAINING TRYPTOPHANASE

A preparative method has been developed to obtain a series of α-deuterated L-amino acids with high chemical yields and quantitative optical yields by stereospecific isotope exchange in D2O by the action of E. coli cells with high tryptophanase action.

Synthesis of Nonproteinogenic (R)- or (S)-Amino Acids. - Analogues of Phenylalanine, Isotopically Labelled and Cyclic Amino Acids from tert-Butyl 2-(tert-Butyl)-3-methyl-4-oxo-1-imidazolidinecarboxylate (Boc-BMI)

The enantiomerically pure glycine derivatives (R)- and (S)-Boc-BMI, commercially available on a kg scale, are used as starting materials (Scheme 1) for the preparation of (i) open-chain amino acids such as α-deuterio amino acids (4,5), β-arylalanines (2), aspartic acid derivatives (6, 7a, 8), or ω-halo amino acids (7b,c, 12, 13, 16, 17, 19, 22), (ii) of α-aminocycloalkanecarboxylic acids (9, 11), and (iii) of heterocyclic α-amino acids (14, 15, 18, 20) containing azetidine, pyrrolidine, piperidine or perhydroazepine rings.Inversion by deprotonation/protonation ordeuteration allows to prepare either enantiomer of an amino acid from the same Boc-BMI enantiomer (Scheme 5).Effects of additives such as the cyclic urea DMPU, lithium salts, or secondeary amines upon the reactivity of lithium enolates are discussed and, in part, exploited.

Asymmetric Synthesis of α-Deuterated α-Amino Acids through Nonenzymatic Transamination Reaction and the Determination of Their Enantiomeric Excesses

Optically active α-deuterated α-amino acids were prepared in methanol-d through Zn2+-catalyzed transamination reaction between the chiral pyridoxamine analogs, (R)- or (S)-15-aminomethyl-14-hydroxy-5,5-dimethyl-2,8-dithia(2,5)pyridinophane and various α-keto acids with enantiomeric excesses ranging from 40 to 94percent.Aliphatic α-keto acids gave α-deuterated α-amino acids, whereas aromatic ones possessing a methylene group between the carbonyl group (ketone) and the aromatic ring underwent concomitant deuterium substitution at the active methylene group to give the amino acids deuterated at both α- and β-positions of the carbonyl group.The use of the (S)-pyridoxamine analog gave the (R)-deuterated α-amino acids in excess and vice versa.The enantiomeric excesses of the amino acids were determined through the analyses of 1H NMR spectra of the Schiff bases produced by the condensation of the amino acids with the chiral pyridoxal analog, (R)- or (S)-15-formyl-14-hydroxy-2,8-dithia(2,5)pyridinophane.The azomethine protons of the diastereomeric Schiff bases were clearly resolved in the spectrum and their intensities well reflected the amount of the diastereomers.