The condensation of 2-amino-2-methylglutaric acid (I) with phthalimide (II) by means of TEA in refluxing toluene gives 2-methyl-2-phthalimidoglutaric acid (II), which is partially reduced with Zn and acetic acid yielding the racemic indolinone derivative (IV). The esterification of (IV) affords the dimethyl ester (V), which is enantioselectively monohydrolyzed by means of ChiroCLEC-BL catalyst affording a mixture of the (S)-monoester (VI) and unchanged (R)-diester (R)-(V), which is separated by flash chromatography. Finally, the chiral monoester (VI) is hydrolyzed with HCl/AcOH.