Palladium-catalyzed coupling of 2,4-diamino-6-iodoquinazoline (I) with trimethylsilyl acetylene (II) affords the silylethynyl quinazoline (III). Subsequent treatment of (III) with tetrabutylammonium fluoride leads to the desilylated acetylene compound (IV).

Condensation between phthaloyl ornithine methyl ester (V) and 4-iodobenzoic acid (VI), via activation with isobutyl chloroformate, furnishes the iodobenzamide (VII). Subsequent coupling of iodo amide (VII) with the ethynyl quinazoline (IV) employing Pd(PPh3)4 and CuI leads to the disubstituted acetylene (VIII). Catalytic hydrogenation of the triple bond in the presence of Pd/C affords (IX). Then, basic hydrolysis of phthalimido ester (IX) by means of Ba(OH)2 produces the target compound.