Patent ID: 7196204

Claim:
A process for the synthesis of (2S)-indoline-2-carboxylic acid of formula (I): wherein a racemic indoline-2-carboxylic acid of formula (III): is reacted with a chiral amine to yield a salt of formula (IV): which is filtered off, to yield: the (2S) isomer of formula (IV a): in the form of crystals, which compound of formula (IV a) is treated with hydrochloric acid to yield the compound of formula (I), and after evaporation of the filtrate, a mixture of the (2S) isomer of formula (IV a) and the (2R) isomer of formula (IV b) in which the (2R) isomer predominates: which mixture is treated with hydrochloric acid to yield a mixture of (2R)-indoline-2-carboxylic acid and (2S)-indoline-2-carboxylic acid in which the (2R) acid predominates, the mixture is racemized by reaction with a sodium hydroxide solution, at a temperature of from 140 to 200° C., under a pressure of from 5 to 15 bars, to yield, after isolation, the compound of formula (III), which is then re-subjected to the series of operations described above, after having carried out between 2 and 6 cycles of the above-described series of operations, all the portions made up of the compound of formula (I) are combined.