Cu/Fe-Catalyzed C-C, C-N and C-S Cross-Coupling Reactions:
Synthesis of Biologically Important Heterocycles

Abstract

Cross-coupling reactions are an important methodology for the formation of various types of carbon-carbon and carbon-heteroatom bonds. Now a days these reactions are applied in a variety of synthetic venues starting from total synthesis of natural and non-natural products to pharmaceutically important molecules and functional materials. The coupling reactions are generally carried out by using a range of transition-metals including Ru, Rh, Pd, Pt, Au, Ni etc. However, the high cost, toxicity of TM and use of ancillary ligands often restrict their utility in organic reactions. Thus, researchers have turned their attention towards the use of less expensive and environment friendly catalyst for the C-C and C-hetero bond forming reactions. Indeed, Cu/Fe-catalyzed cross-coupling reactions have gained much attention owing to the low cost and environmental friendly nature of Cu/Fe catalysts. Indeed, significant progress has been made on the use of homogeneous Cu/Fe catalysts in organic synthesis. However, homogeneous catalysis suffers from the problematic separation of the catalyst for reuse. Furthermore, the homogeneous catalysts tend to lose their catalytic activity because of aggregation of the metal catalyst. To circumvent the aforementioned problems, several heterogeneous catalytic systems for cross-coupling reactions have been developed. In recent years, the catalytic activity of nanoparticles in organic transformations has been exploited owing to their high surface area. However, the small size of the nanoparticles, renders the incomplete separation of the catalyst from the reaction medium. To make the separation process simple and efficient with retention of catalytic activity, magnetic nanoparticles are the attractive solution. In this context, our detailed efforts on the development of cost effective Cu/Fe-based catalyst systems for C-C and C-hetero bond forming reactions and their applications in the synthesis of biologically important heterocycles have been described in this thesis.