[BMIM][HSO4] as an efficient ionic liquid catalyst for microwave assisted one pot multi component synthesis of 1, 4-dihydropyridines

Abstract

A highly efficient and environmentally friendly method was established to synthesise 1,4-dihydropyridines under microwave radiation, using [BMIM][HSO4] as a catalyst. Under ideal conditions, the desired products were formed in a reaction time of only three minutes at the optimum temperature (100 °C), and the high yield (90%) and stability of the [HSO4] catalyst, which was good and recyclable, allowed efficient use for many reaction cycles without noticeable loss of activity. The process showed a wide range of substrate tolerances, including amines, β-ketoesters, and aldehydes, resulting in a library of it being attractive that 1,4-dihydropyridine derivatives occurred compared to conventional methods. With its effectiveness and energy savings, this method offered distinct advantages in terms of environment and sustainability. According to the proposed mechanism, the catalyst catalyses reactions via Brønsted acid, facilitating important chemical steps. This work presents a practical and promising method for the synthesis of 1,4-dihydropyridines, which may find utility in medicinal chemistry and pharmaceutical development.