An efficient synthesis of the 4(3H)-quinazolinone-based alkaloids , 1,2,3,5-tetrahydropyrrolo[2,1-b]quinazoline-5- one has been achieved in good overall yields by using the strategy of regioselective lithiation-intramolecular electrophilic reaction as a key–step. Both the molecules have been synthesized in just two-steps from readily available starting materials. Several synthetic analogs of natural product 1,2,3,5-tetrahydropyrrolo[2,1- b]quinazoline-5-one , an alkaloid containing quinazolinone moiety are being reported in this communication. Novel synthetic method for the synthesis of 1,2,3,5-tetrahydropyrrolo[2,1-b]quinazoline-5-one analogs are reported. Final products were supported by FTIR , 1H NMR , 13C NMR and Mass spectroscopic measurements and possess moderate to good antifungal and antibacterial activities.