Nitration of quinazolone (I) by reaction with HNO3/H2SO4 affords 7-chloro-6-nitro-4-quinazolone (II), which is then chlorinated with phosphorus oxychloride (POCl3) to provide quinazoline (III). Selective amination of the quinazoline ring of (III) by reaction with 4-chlorophenethylamine (IV) in isopropanol in the presence of Et3N yields compound (V), which is finally converted into the desired compound by condensation with piperazine (VI) in refluxing butanol in the presence of DIEA. Alternatively the target product can be obtained by the following procedure: Condensation of quinazolone derivative (II) with piperazine (VI) in refluxing butanol in the presence of DIEA affords compound (VII), which is treated with POCl3 and finally subjected to condensation with 4-chlorophenethylamine (IV) in isopropanol in the presence of Et3N.