C(sp)–C(sp2) bond formation via Sonogashira cross-coupling reactions on 6-halo-2-cyclopropyl-3-(pyridyl-3-ylmethyl)quinazolin-4(3H)-ones with appropriate alkynes was explored. Optimization of reaction conditions with various catalysts, ligands, bases, and solvents was conducted. The combination of PdCl2(MeCN)2 with X-Phos proved to be the best metal–ligand system for this conversion in the presence of triethylamine (Et3N) in tetrahydrofuran at room temperature for iodosubstrates, at 80°C for the bromosubstrates in 8 h, and also for the chlorosubstrates in 16 h. We also demonstrated synthesis of a successful diversity-oriented synthesis library of highly functionalized quinazolinones via Cu-free Sonogashira coupling of diverse aryl halides and azido-alkyne (“click”) ligation reactions with substituted azides. The library exhibited significant antimicrobial activity when screened against several microorganisms. © 2017 Wiley Periodicals, Inc.