Kanegafuchi Chemical Industry Co., Ltd.

Yasushi Nose

Kiyoshi Watanabe

Takehisa Ohashi

Masami Shimazaki

Kenji Nomura

An improved process for preparation of an optically active N-(3-mercapto-2-D-methylpropanoyl)-L-amino acid represented by formula (I): ##STR1## from an N-(3-chloro-2-D-methylpropanoyl)-L-amino acid represented by formula (II): ##STR2## (Y in (I) and (II): CH.sub.2 or sulfur; Q in (II): hydrogen, Na, K or NH.sub.4), which is characterized by reacting the compound (II) with an alkali trithiocarbonate, of which the molar ratio to the compound (II) is not less than 1.5, in an aqueous medium at a temperature of from about 60.degree. C. to about 90.degree. C., and hydrolyzing the resulting product with an acid. It is preferable to use sodium trithiocarbonate as the alkali trithiocarbonate, mineral acid as the acid, or water or aqueous alcohol as an aqueous medium.

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Takasago, Japan

Yasushi Nose