Optically active sulphur-containing amino acid derivatives, their preparation, their polymerisation to give optically active polymers and the use thereof

An optically active sulphur-containing amino acid derivative of the formula ##STR11## in which R represents hydrogen, methyl or fluorine,

• R.sub.1 represents hydrogen or C.sub.1 -C.sub.4 -alkyl,
• R.sub.2 represents a straight-chain, branched or cyclic alkyl radical having up to 10 C atoms, or phenyl
• R.sub.3 represents a C.sub.10 -terpenyl radical, an adamantyl radical or a decahydronaphthyl radical, or represents a branched alkyl or cycloalkyl radical having from 2 to 20 C atoms, which is optionally mono-, di- or trisubstituted by halogen, alkoxy having 1 to 4 C atoms, or C.sub.3 -C.sub.12 -cycloalkyl, wherein the aryl and cycloalkyl radicals are optionally substituted by C.sub.1 -C.sub.4 -alkyl, and
• A represents a methylene or dimethylene group which is optionally mono- or di-C.sub.1 -C.sub.4 -alkyl-substituted.