Green and Efficient Knoevenagel Condensation Catalysed by a DBU Based ionic Liquid in Water

An efficient, clean and facile protocol for the Knoevenagel condensation of aromatic aldehydes with active methylene compounds catalysed by task specific ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate in an aqueous medium has been developed. The reactions proceed at room temperature and high to excellent yields were afforded. The workup procedure is very simple. The ionic liquid could be recycled for 10 runs without noticeably loss of its catalytic activity.