Cl.[K].NC1C=CC(F)=CC=1S.O.[C:13]1([CH3:23])[CH:18]=[CH:17][C:16]([S:19]([OH:22])(=[O:21])=[O:20])=[CH:15][CH:14]=1>O1CCCC1.O>[CH3:23][C:13]1[CH:18]=[CH:17][C:16]([S:19]([OH:22])(=[O:21])=[O:20])=[CH:15][CH:14]=180 ml of water and 60 g (0.592 mole) of 36% hydrochloric acid were placed in a 500-ml flask as a reactor, and cooled to 0 to 2° C. Thereto was dropwise added, at 0 to 5° C. with stirring, 96.0 g (0.112 mole) of an aqueous solution of a potassium salt of 2-amino-5-fluorothiophenol. The system had a pH of 0.90. Thereto was added 20.0 g (0.105 mole) of p-toluenesulfonic acid monohydrate. Then, a solution of D-alanine-N-carboxyanhydride (16.7 g, purity: 78.3%, 0.318 mole) dissolved in tetrahydrofuran (30 ml) (the solution was beforehand prepared at 16 to 20° C.) was added dropwise at 16 to 20° C. Aging was conducted at 15 to 20° C. for 4 hours. The resulting crystals were collected by filtration and dried at 60° C. to obtain 31.5 g of a p-toluenesulfonate of [2-(6-fluorobenzothiazolyl)]ethylamine (purity: 98.95%) (the yield was 75.5% relative to the potassium salt of 2-amino-5-fluorothiophenol).
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