Process for preparing aripiprazole - Patent 6995264 The present invention provides a process for preparing aripiprazole in a high purity and a high yield. According to the process of the present invention, aripiprazole is prepared by the reaction of a carbostyril compound represented by general formula (2): Banno, K. et al., “Studies on 2(1H)-Quinolinone Derivatives as Neuroleptic Agents. I. Synthesis and Biological Activities of (4-Phenyl-1-Piperazinyl)-Propoxy-2(1H)-Quinolinone Derivatives”, Chemical and Pharmaceutical Bulletin, Pharmaceutical Society of Japan, Tokyo, Japan, vol. 36, No. 11, pp. 4377-4388, (1988).The present inventors have now discovered a process for preparing aripiprazole in further higher purity and yield. It is a common technical knowledge in the field of chemical science that a chemical reaction can progress in a high efficiency when the substrate of the reaction is dissolved in the reaction system. According to the above-mentioned knowledge, it is virtually impossible for one of ordinary skilled in the art to think of using water as a reaction medium for a reaction between a carbostyril compound of general formula (2), which is entirely insoluble in water, and a piperazine compound of formula (3) or a salt thereof. In addition, the ordinary skilled in the art can easily expect that the group X in the molecule of carbostyril compound represented by general formula (2) has a very high possibility of conversion into a hydroxyl group by hydrolysis with water. Thus, the ordinary skilled in the art can easily expect that purity and yield of aripiprazole will be lowered under such a condition.
