title: Knoevenagel reaction in [MMIm][MSO₄]: synthesis of coumarins.
abstract: The ionic liquid 1,3-dimethylimidazolium methyl sulfate, [MMIm][MSO₄], together with a small amount of water (the amount taken up by the ionic liquid upon exposure to air), acts efficiently as both solvent and catalyst of the Knoevenagel condensation reactions of malononitrile with 4-substituted benzaldehydes, without the need for any other solvent or promoter, affording yields of 92%-99% within 2-7 min at room temperature. When L-proline is used as an additional promoter to obtain coumarins from o-hydroxybenzaldehydes, the reaction also proceeds in high yields. Work-up is very simple and the ionic liquid can be reused several times. Some of the coumarins obtained are described for the first time.
authors.affiliation: Department of Organic Chemistry, Faculty of Chemistry, University of Vigo, Pontevedra 36310, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Verdía
authors.forename: Francisco
authors.initials: F
authors.lastname: Santamarta
authors.forename: Emilia
authors.initials: E
authors.lastname: Tojo
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry; D002384:Catalysis; D003374:Coumarins / Q000138:chemical synthesis*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids; D009570:Nitriles / Q000737:chemistry; D011392:Proline / Q000378:metabolism; D012997:Solvents; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D014867:Water
chemical_list: C516814:1,3-dimethylimidazolium; D001547:Benzaldehydes; D003374:Coumarins; D007093:Imidazoles; D052578:Ionic Liquids; D009570:Nitriles; D012997:Solvents; D013463:Sulfuric Acid Esters; D014867:Water; D011392:Proline; C000945:dicyanmethane; C033522:methyl sulfate