Coumarin Synthesis via Knoevenagel Condensation Reaction in 1,1,3,3-N,N,Nʹ,Nʹ-Tetramethylguanidinium Trifluoroacetate Ionic Liquid

Coumarin derivatives were synthesized in relatively high yields via Knoevenagel condensation reaction of an orthohydroxyaryl aldehyde and an activated β-dicarbonyl C-H acid in the presence of a recyclable ionic liquid 1,1,3,3-N,N,Nʹ,Nʹ- tetramethylguanidinium trifluoroacetate under either classical heating conditions or using microwave irradiation. Application of microwave irradiation decreased the required time by a factor of about 200. The ionic liquid could be recycled several times without loss of efficiency with regards to the reaction times and yields