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 work-up procedure is very simple. The ionic liquid could be recycled for 10 runs without noticeably loss of its catalytic activity. [ABSTRACT FROM AUTHOR]