Executive Summary : | The methylene (CH2) group is an important functionality found in many biologically active molecules and plays a significant role in regulating the pharmaceutical properties of a molecule. Most of the top-selling drugs of 2011 contain at least one methyl group that is bound to a carbon, nitrogen, or oxygen atom. Nitrogen bridgehead-fused heterocycles containing indoles and imidazo[1,2-a]pyridines are common structural motifs in pharmacologically important molecules, with diverse biological activities i.e., antiviral, analgesic, antifungal, antitumor, antibacterial, anti-inflammatory, antiprotozoal, antiapoptotic, antipyretic, anxioselectives, and hypnoselective activity. On the other hand, homologation chemistry represents a valid approach for incorporating a methylene group (-CH2) into a given molecule. This strategy brings significant changes in physical and chemical properties of the organic skeleton. Ideally, the homologation protocol would precisely introduce the methylene fragment between a C-H bond. A plethora of reagents were used for this strategy i.e., DMSO, DMF, tetramethylurea, and N,N-dimethylacetamide (DMA) using catalysts such as Ru, Ti, Cu etc. In the recent years, one of the core research goals of chemists is to develop existing chemical methods “greener” and with 100% atomic efficiency to ensure a sustainable and safe environment for future generations. Thus, the development of efficient C1 homologation has become a predominant field of research in synthetic chemistry. It is widely acknowledged that incorporation of methylene group into the organic compound brings significant changes in the parent molecule. Hence, we are aiming to incorporate the methylene group to validate their biological activities. Thus, based on our previous experience on rongalite chemistry, we are interested to develop a transition metal-free C(sp2)–H methylenation of heterocycles to prepare various methylene bridged compounds |