Disclosed herein is a process for the preparation of compound (1S,2S)-2-(4-carbamoyl-phenyl)-cyclopropanecarboxylic acid according formula (Ia), comprising reacting a compound of formula IX with (1) a base and peroxide and then (2) an acidic solution. Also disclosed is a process for the preparation of compounds according formula (Ib) and (Ic) (4-{ (1S,2S)-2-[((R)-4-cyclobutyl-2-methylpiperazin-1-yl)carbonyl]-cyclopropyl} benzamide and 4-{ (1S,2S)-2-[(4-cyclobutylpiperazin-1-yl)carbonyl]-cyclopropyl} -benzamide respectively) starting from a compound of formula (Ia).
