One-pot three-component synthesis of α-amino nitriles using ZnO as a heterogeneous, reusable, and eco-friendly catalyst

Various forms of alpha-amino nitrile molecules are found to exert strong impacts on the synthesis of multiple organic compounds such as pharmaceuticals, amino acids, agrochemical agents, and pesticides. Spherical ZnO nanoparticles (NPs) prepared by a simple co-precipitation method are an efficient heterogeneous catalyst for the synthesis of vital intermediate alpha-amino nitriles. The present protocol was investigated via one-pot synthesis of alpha-amino nitriles over ZnO NPs using a three-component coupling reaction of aldehydes, amines, and trimethylsilyl cyanide in acetonitrile. The feasibility of our synthesis approach was assessed with respect to the purity and yield of synthesized products in relation to several controlling variables (e.g., ZnO molar ratio, reaction time, amines/aldehydes types, and solvent). The qualitative characteristics of alpha-amino nitrile products were evaluated by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and mass spectroscopic analysis. A high yield (81-95%) of pure alpha-amino nitriles within a short reaction time (45-75 min) along with good recyclability of the catalyst (e.g., without significant loss in performance over five cycles) was confirmed as the distinctive merits of this new eco-friendly synthetic method. This study confirms that various amines including sterically crowded secondary amines should react efficiently with benzenoid plus non-benzenoid aldehyde to yield alpha-amino nitriles. The selected route is very fast as well as economical. Hence, this method can be used for large-scale production of a variety of biologically important molecules through alpha-amino nitriles. (C) 2019 Elsevier Ltd. All rights reserved.