An industrially advantageous method of producing &bgr;-halogeno-&agr;-aminocarboxylic acids is provided. Methods are also provided of producing optically active N-protected-S-phenylcysteines having high optical purity and of intermediates thereof, respectively, in which the above production method is utilized.
A method of producing &bgr;-halogeno-&agr;-aminocarboxylic acids or salts thereof is disclosed which comprises halogenating the hydroxyl group of a &bgr;-hydroxy-&agr;-aminocarboxylic acid (in which the basicity of the amino group in &agr;-position is not masked by the presence of a substituent on said amino group) or a salt thereof with an acid with a halogenating agent. A method of producing optically active N-protected-S-phenylcysteines represented by the general formula (3) or salts thereof is further disclosed which comprises applying the above production method to optically active serine or a salt thereof and then carrying out treatment with an amino-protecting agent and reaction with thiophenol under a basic condition.
本发明提供了一种工业上有利的制备&bgr;-卤代-&agr;-
氨基
羧酸的方法。还提供了制备高光学纯度的N-保护-S-苯基半胱
氨酸及其中间体的方法,其中利用上述生产方法。本发明还揭示了一种制备&bgr;-卤代-&agr;-
氨基
羧酸或其盐的方法,包括用具有卤代作用的酸卤代&bgr;-羟基-&agr;-
氨基
羧酸(其中&agr;-位置的
氨基基性未被该
氨基上的取代基掩盖)或其盐的羟基。本发明还揭示了一种制备由通式(3)表示的光学活性N-保护-S-苯基半胱
氨酸或其盐的方法,其中包括将上述生产方法应用于光学活性
丝氨酸或其盐,然后在碱性条件下进行
氨基保护剂的处理和与
硫苯酚的反应。