1983 Volume 56 Issue 12 Pages 3652-3656
Optically active α-deuterated α-amino acids were prepared in methano-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 94%. 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 carboxyl group. The use of the (S)-pyridoxamine analog gave the (R)-deuterated α-amino acids in excess and vice versa. The enatiomeric 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.
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