PURPOSE: To obtain the titled compound useful as a raw material for pharmaceuticals, by epimerizing an easily soluble diastereomer salt and crystallizing a hardly soluble diastereomer salt among specific optically active α- phenylethanesulfonic acid salts of a DL-aspartic acid derivative.
CONSTITUTION: Among two kinds of diastereomer salts of DL-aspartic acid β-methyl ester.optically active α-phenylethanesulfonic acid salt or DL-aspartic acid β-methyl ester.optically active α-(p-methylphenyl)ethanesulfonic acid salt, an easily soluble diastereomer salt is converted into a hardly soluble diastereomer salt by epimerizing in a solvent such as acetonitrile in the presence of an aldehyde at 0W100°C and the crystallized hardly soluble diastereomer salt is separated from the system. If necessary, the salt is subjected to recrystallization, ion exchange resin treatment, neutralization, etc., to obtain the objective compound in high yield and purity.
OTSUKI OSAMU
YOSHIOKA RYUZO
| JPS4897801A | 1973-12-13 | |||
| JPS59170057A | 1984-09-26 |
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