VERFAHREN ZUR HERSTELLUNG VON BETA-HALOGEN-ALPHA-AMINO-CARBONSÄUREN, PHENYLCYSTEINDERIVATEN UND IHREN ZWISCHENPRODUKTEN

摘要

Preparation of optically active N-protected S-phenylcysteine (III) using new process for preparing beta -halogeno-alpha -aminocarboxylic acid (I) starting materials. Preparation of beta -halogeno-alpha -aminocarboxylic acid (I) comprises treating a beta -hydroxyaminocarboxylic acid (IV) or its salt with a halogenating agent and an acid to halogenate the hydroxy group. In (IV) the basicity of the amino group at the alpha -position is not shielded by the presence of the substituent on the amino group. Independent claims are also included for: (1) a process for the preparation of an optically active N-protected S-phenylcysteine of formula (III) or its salt comprising: (A) subjecting optically active serine or its salt to the above process to give a beta -halogenated alanine compound of formula (I'); (B) protecting the amino group of (I') to give a protected compound of formula (II); and (C) reacting (II) with thiophenol under basic conditions (2) intermediates (I') and (II). [Image] R1amino protecting group and R0 = H; or R1+R0amino protecting group.