A method for the synthesis of the title compound [i.e., 7-hydroxy-3,4-dihydro-2(1H)-quinolinone] is reported here.By substituting aluminum chloride (AlCl3) with a small amount of boron trifluoride etherate, 7-hydroxy-3,4-dihydro-2(1H)-quinolinone was synthesized in two steps starting from 3-aminophenol.It was pure and could be used to synthesize aripiprazole [i.e., 7-[4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butoxy]-3,4-dihydro-2(1H)quinolinone] without further purification (no data).The structure of the target compound was confirmed by elemental anal., MS, NMR, 13C-NMR, IR.This method is convenient, environmentally friendly and suitable for industrial scale-up production