Abstarct: Heterocyclic compounds are one of the largest and most diverse family of organic compounds. Nitrogen heterocycles play a fundamental role in biological processes, pharmaceutical industry, materials science and they are widespread in natural products. In this research work, some new nitrogen hetrocycles were synthesized via multi-component reactions and carbon-carbon coupling reactions in presnnce of the new nanoboehmites supported catalyst and palladium. 1. We demonstrated an environmentally friendly method for the syntheses of 3-Methyl-4-(aryl)-7-thioxo-4,6,7,8-tetrahydropyrazolo-[4',3':5,6]pyrano[2,3-d]pyrimidin-5(1H)-one using m-SABNPs as an efficient and reusable nanocatalyst. This method offers several advantages like milder reaction condition, shorter reaction time, cleaner reaction, green and reusability of the catalyst, and high reaction yield. 2. A new boehmite silylpropyl amine sulfamic (m-SABNPs) was conveniently prepared from commercially available and inexpensive 3-aminopropyltriethoxysilane via immobilization on boehmite nanoparticles, followed by reacting with chlorosulfunic acid. It was found that this heterogeneous sulfamic acid is a highly efficient catalyst for the syntheses of 5-amino-1,3-aryl-1H-pyrazole-4-carbonitriles. 3. synthesis of a new BNPs-3-propylimidazolopyridinium hydrogen sulfate proved to be an efficient heterogeneous catalyst for the synthesis of 3-Methyl-4-(aryl)-7-oxo-4,6,7,8-tetrahydropyrazolo-[4',3':5,6]pyrano[2,3-d]pyrimidin-5(1H)-one via a one-pot fourcomponent reaction. 4. Synthesis of 2-amino-4H-tetrahydrobenzo[b]pyran was catalyzed by BNPs-3-propylimidazolopyridinium hydrogen sulfate. 5. A new functionalized boehmite nanoparticle (BNP) catalyst immobilized copper iodide is synthesized. The catalyst showed a great activity in the Sonogashira coupling reaction of aryl halides with terminal alkynes in DMF under an Ar atmosphere. 6. The catalyst-free, multi-component reactions of aldehydes, malononitrile, and sodium azide at a relatively low temperature in magnetized water provided 5-substituted 1H-tetrazoles in high-to-excellent yields. 7. New 2-substituted pyrazolo[5,1-b][1,3]oxazoles are synthesized through the Sonogashira coupling reaction of 2-iodomethyl-6-methylpyrazolo[5,1-b][1,3]oxazole with terminal alkynes in the presence of a palladium catalyst. This process is carried out in the absence of any copper salt, and provides an ecofriendly and efficient method for the synthesis of the products in water in good-to-high yields. The structures of all the synthesized compounds were confirmed by the spectroscopic data. For some of the compounds synthesized, the pharmaceutical and biological properties such as the anti-oxidant, anti-bacterial and cytotoxic activities were examined.