Triethylamine → (4R)-4,5-Dihydro-2-(methylthio)-4-thiazolemethanol

A 1.5 ml solution of acetonitrile anhydride containing 219 mg of 3-hydroxyazetidine hydrochloride (5) was cooled to 0° C. in the stream of nitrogen, and, to this solution, there were added 0.31 ml of triethylamine and subsequently a 0.3 ml solution of acetonitrile anhydride containing 250 mg of chloroethylisothiocyanate dissolved therein, and the resultant solution was stirred for 30 minutes at the same temperature, and, after left still until it had a room temperature, the solution was further stirred for two hours. Next, dichloromethane was added to the reaction liquid, and the resultant solution was washed with a saturated aqueous solution of potassium carbonate, and, thereafter, the dichloromethane layer was dried with magnesium sulfate, and then was condensed under reduced pressure, and, thus, there was obtained 300 mg (yield: 95%) of 3-hydroxy-1-(1,3-thiazolin-2-yl)azetidine (6) in the form of colorless needle crystal.