Applications of Schiff Bases and their Metal Complexes in Catalytic Transformations

Schiff base ligands can easily coordinate with metal ions and forms stable complexes, which facilitate the utilization of Schiff base metal complexes as catalyst in organic synthesis. Various routes for the synthesis and application of various Schiff base metal complexes in the field of catalytic transformations to synthesize organic compounds economically and more selectively are well-documented. Here we discuss the synthesis of 2-Amino-3-cyano-4H-pyrans or 4H-chromenes, synthesis of polyhydroquinoline derivatives by the Hantzsch reaction, Biginelli reaction, Suzuki–Miyaura and the Sonogashira cross-coupling reactions, synthesis of tetrazoles, synthesis of β-hydroxy-1,2,3-triazole, synthesis of N-aryl amines by Chan–Lam coupling, catalytic epoxidation of alkenes, catalytic reduction of aromatic ketones into alcohol etc. Numerous Schiff base complexes can withstand higher temperature that provides them extra flexibility for their catalytic action even at higher temperature. Versatile nature of Schiff base (SB) ligands also prompted researchers to focus on studying catalytic activity where metal-SB immobilized on core-shell magnetic nanoparticles as nanocatalyst. The catalytically active Schiff base metal complexes are prerequisite to enhance the yields of stereospecific, regioselective and chemoselective products. This review highlights the Schiff base metal complexes as a catalyst to complicated organic synthesis into a simple one pot synthesis, thus may be beneficial to both researchers and industries in the field of catalytic reaction.