Preparation of optically active (2RS,3SR)-2-amino-3-hydroxy-3-phenylpropanoic acid (threo-beta-phenylserine) via optical resolutions by replacing and preferential crystallization.
To obtain optically active threo-2-amino-3-hydroxy-3-phenylpropanoic acid (1) via optical resolutions by replacing and preferential crystallization, the racemic structure of (2RS,3SR)-1 hydrochloride [(2RS,3SR)-1.HCl] was examined based on the melting point, solubility, and infrared spectrum. (2RS,3SR)-1.HCl was indicated to exist as a conglomerate at room temperature, although it forms a racemic compound at the melting point. When, in optical resolution by replacing crystallization, L-phenylalanine methyl ester hydrochloride (L-2) was used as the optically active co-solute, (2R,3S)-1.HCl was preferentially crystallized from the supersaturated racemic solution; the use of D-2 as the co-solute afforded (2S,3R)-1.HCl with an optical purity of 95%. In addition, optical resolution by preferential crystallization was successfully achieved to give successively (2R,3S)- and (2S,3R)-1.HCl with optical purities of 90-92%. The (2R,3S)- and (2S,3R)-1.HCl purified by recrystallization from 1-propanol were treated with triethylamine in methanol to give optically pure (2R,3S)- and (2S,3R)-1.
Shiraiwa
Tadashi
T
Unit of Chemistry, Faculty of Engineering and High Technology Research Center, Kansai University, Yamate-cho, Osaka 564-8680, Japan. shiraiwa@ipcku.kansai-u.ac.jp
Kawashima
Yuka
Y
Ikaritani
Atsushi
A
Suganuma
Yumiko
Y
Saijoh
Reiichi
R
D003460:Crystallization; D018360:Crystallography, X-Ray; D006900:Hydroxylation; D015394:Molecular Structure; D009904:Optical Rotation; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D012995:Solubility; D013237:Stereoisomerism
C013048:beta-hydroxyphenylalanine; D010649:Phenylalanine