57224-63-2

39994-75-7

501-53-1

57224-63-2

In a 2L beaker, 100 g of L-threonine methyl ester hydrochloride was dissolved in 600 ml of water and the pH was adjusted to a suitable range using sodium bicarbonate. Subsequently, 110 g of benzyl chloroformate (Z-Cl) was slowly added dropwise and the pH of the reaction system was kept between 8-9, which was adjusted using 2 M sodium hydroxide solution. After completion of the reaction, 1 L of ethyl acetate was added for extraction. The organic phase was washed sequentially with 500 ml of water and 500 ml of saturated saline, and then dried with 100 g of anhydrous sodium sulfate. After filtration, it was concentrated to dryness under reduced pressure to obtain a solid product. The solid was dissolved in 600 ml of a suitable solvent for crystallization, filtered and dried to give 140 g of N-benzyloxycarbonyl-L-threonine methyl ester (Z-Thr-OMe) in 89.1% yield.