Heteropoly acid in ionic liquid — An efficient and recyclable system for one-pot three-component Mannich reaction

Abstract

This paper describes a one-pot three-component Mannich reaction, catalyzed by phosphotungstic acid (H 3 PW 12 O 40 ), a heteropoly acid in ionic liquid. The catalyst was found to be mild and efficient, and the protocol affords β-amino ketones in good yields under ambient conditions. Several ionic liquids and conventional organic solvents were employed for the reaction. The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF 4 ) offered the best results in terms of yield of the products. It was observed that a homogeneous reaction medium proved beneficial for the yield of the reaction.Key words: Mannich reaction, β-amino ketones, phosphotungstic acid, ionic liquid, recyclability.