The reaction of 2-amino-5-nitrobenzoic acid (I) with N,N-dimethylformamide dimethylacetal (II) by heating at 100 C gives the formamidine (III), which is cyclized with 3-bromoaniline (IV) in refluxing acetic acid yielding 4-(3-bromophenyl)-6-nitroquinazoline (V). The reduction of (V) with Fe and acetic acid affords the amine (VI), which is finally acylated with 2-butynoic acid by means of isobutyl chloroformate and N-methylmorpholine in THF.