Process for the preparation of an optically active indoline-2-carboxylic acid or derivative thereof

Process for the preparation of an optically active N-acyl-indoline-2-carboxylic acid in which a mixture of enantiomers of N-acyl-indoline-carboxylic acid is contacted with an optically active resolving agent and the optically active N-acyl-indoline-2-carboxylic acid is liberated from the resulting diastereomeric salt, as resolving agent use being made of a compound of formula 1, where R1 represents an alkyl group and R2 a hetero-aryl group or where R1 and R2 together with the C atoms to which they are bound form a cycloalkyl group with 5-8 C atoms, fused with a hetero-aryl group. Preferably, a mixture of enantiomers of an N-acyl-indoline-2-carboxylic acid is prepared in a process comprising the steps of Fischer indole cyclization of a 2-phenylhydrazone propionic acid or a derivative thereof in the presence of an acid catalyst, if necessary hydrolysis of the derivative to the corresponding acid, acylation at the N-position and reduction of the indole compound to the corresponding indoline compound, after which the resulting N-acyl-indoline-2-carboxylic acid is subjected to the resolution. The 2-phenylhydrazonopropionic acid or a derivative thereof is preferably obtained from phenylhydrazine and pyruvic acid or the corresponding derivative thereof.