Mechanistic studies on counter-ionic effects of camphorsulfonate-based ionic liquids on kinetics, thermodynamics and stereoselectivity of β-amino carbonyl compounds

Abstract

Catalysis is important in various applications of organic chemistry and its output product control for stereoselective compounds is outrageous. Establishment of experimental facts of stereoselective compounds from catalysis and their validation using theoretical evidences is the key to understand various mechanisms of optically active compounds. A family of new ionic liquids (ILs) with various imidazolium cations and camphorsulfonate anion as environmentally benign liquid salts have been synthesized and deployed for catalysis of β-amino carbonyl compounds. The products were formed using ILs as a homogeneous catalyst with excellent product yield and diastereoselectivity. The effect of counter ions, Hammett acidity and viscosity of ILs along with solvent and temperature are explored in terms of reaction kinetics and product yields. Density functional theory (DFT) was used to investigate thermodynamical study of mechanistic pathway of the reaction. The DFT calculations predicted that the catalysis mechanism involved both counterions of the IL. Moreover, it is evidenced that the syn-pathway required lower activation energy while anti-pathway led to thermodynamically stable product. This study explores new avenues for using ILs as potential homogeneous catalysts for the production of stereoselective species.