Nucleophilic Substitution Reactions in the Synthesis of Selenium Donor Containing Schiff Bases : Applications of Metal Complexes in Homogeneous Catalysis

Schiff bases containing selenium donor sites are emerging as a prominent class of ligands used for homogeneous catalysis. Such ligands are designed using various routes. However, the most frequently utilized route for the synthesis of such ligands is condensation reaction between primary amines (having Se donor sites) and carbonyl compounds. Selenium donor sites are incorporated in the framework of primary amines via nucleophilic substitution reaction between the chloro derivative of alkanamine and PhSeNa. A variety of such Schiff bases have been used to obtain the metal complexes of various metals (such as palladium, ruthenium, platinum, rhodium, and iridium). These metal complexes have the potential to catalyse different organic reactions, such as Suzuki coupling reaction, Heck coupling reaction, Sonogashira coupling reaction, transfer hydrogenation reaction, O-arylation of phenol, and oxidation of alcohols. This article covers important synthetic methodologies used in designing Schiff bases containing Se donor sites and their catalytically active metal complexes. The most significant component of this article is the critical analysis of the applications of such complexes in homogeneous catalysis of various chemical transformations. Substrate scopes have been analyzed. Factors which are responsible for variations in catalytic performances (on the basis of TON and % conversion/yield) have been highlighted. Some light has also been thrown on the mechanistic aspects of catalysis. Conclusions and future perspectives of the field have also been discussed.