Cyclization of N-acetyl dimethylanthranilic acid (I) with acetic anhydride produced benzoxazinone (II) which, upon treatment with aqueous ammonia, furnished trimethylquinazolinone (III). Incorporation of the N-(pivaloyloxy)methyl (POM) protecting group of (III) gave (IV), and subsequent regioselective bromination with N-bromosuccinimide in the presence of AIBN yielded the 6-bromomethyl compound (V). Condensation of (V) with p-aminobenzoate derivative (VI) afforded tertiary amine (VII). After trifluoroacetic acid-promoted cleavage of the tert-butyl ester of (VII), coupling with pentafluorophenol in the presence of DCC provided pentafluorophenyl ester (VIII). The title compound was then obtained by condensation of (VIII) with the tetrazolyl aminoester (IX) in the presence of 1-hydroxybenzotriazole, followed by basic hydrolysis of both methyl ester and POM protecting group.