An environmentally benign one pot synthesis of substituted quinolines catalysed by fluoroboric acid based ionic liquid

Abstract

Organic synthesis generally required large amount of solvent, avoiding the use of organic solvents in synthesis is a paradigm shift directed at developing more benign chemistry, and with ionic liquids surprisingly can lead to access to new compounds. An elegant one-pot synthesis of quinoline derivatives has been achieved by reaction of substituted anilines with β-ketoester at 60°C in ethanol using an ionic liquid [Et3NH]+[BF 4]- as catalyst. All the reactions gave products with high degree of purity and excellent yield (78.93%) within the shorter span of time (20.65 min) than those reactions with conventional methods. The screening of solvents as well as the reuse of ionic liquid has been evaluated. The structure of the products has been elucidated by spectral and analytical data. The present scope and potential economic impact of the reaction are demonstrated by the synthesis of substituted quinolines. Remaining challenges and future perspectives of the new transformation are discussed. © Indian Academy of Sciences.