The cyclization of 2-amino-5-bromobenzoic acid (I) with 3-phenylpropionyl chloride (II) by means of DMAP and Et3N in DMF gives the benzoxazinone (III), which by heating with glycine methyl ester (IV) yields the quinazolinone (V). The hydrolysis if (V) with NaOH in THF/water affords 2-[6-bromo-4-oxo-2-(2-phenylethyl)-3,4-dihydroquinazolin-3-yl]acetic acid (VI), which is condensed with the monoprotected hexane-1,6-diamine (VII), by means of HOBt, EDC and NMM to provide the amide (VIII). The condensation of (VIII) with phenylboronic acid (IX) by means of palladium tetrakis(triphenylphosphoine) gives the 6-phenyl substituted quinazolinone (X), which is finally deprotected with HCl.