Abstarct: Heterocyclic compounds are one of the largest and most diverse families of organic compounds. Nitrogen containing heterocycles play a fundamental role in biological processes, pharmaceutical industry, and material science, and they are widespread in natural products. In this research work, some new nitrogen heterocycles are synthesized via carbon-carbon and carbon-nitrogen coupling reactions in the presence of the palladium/copper catalyst, as follow: Multi-component synthesis of new 1,2,4-trisubstituted pyrrolo[1,2-a] quinoxalines from 3-chloroquinoxalin-2-amines, propargyl bromide, and secondary amines by the Sonogashira coupling reaction. One-pot synthesis of quinoxaline chalcones from commercially available calcium carbide, aromatic aldehydes, and secondary amines through palladium-catalyzed coupling reactions. A one-pot synthetic approach for the construction of thiazolo[3,2-a]benzimidazole-lixnked quinazolines from 2,4-dichloroquinazoline, terminal alkynes, secondary amines, and 1H-benzo[d]imidazole-2(3H)-thione in the presence of the palladium-copper catalyst and iodine as additive. One-pot palladium-catalyzed synthesis of functionalized 10H-pyrido[1,2-a]quinoxalin-10-ones from 3-chloroquinoxalin-2-amines, terminal alkynes, and 1,3-dicarbonyl compounds under copper-free conditions. The structures of all the synthesized compounds were confirmed by the spectroscopic data. A number of synthesized compounds were evaluated for anti-bacterial activities.