The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in the recyclable ionic liquid [bmim]BF 4 at room temperature in the presence of catalytic amounts of piperidine. ... The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in the recyclable ionic liquid [bmim]BF 4 at room temperature in the presence of catalytic amounts of piperidine. ... Meldrum's acid (1) was first discovered in 1908, [ 1 1. ...