Metal-containing ionic liquids as efficient catalysts for hydroxymethylation in water

The iron-containing ionic liquid butylmethylimidazolium tetrachloroferrate (bmim-FeCl4) proved to be an efficient and recyclable catalyst for the hydroxymethylation of beta-keto esters using aqueous formaldehyde and a low catalyst loading of up to 0.1 mol-% without co-solvents or additional surfactants. An useful and high-yielding approach to hydroxymethylated keto esters as well as to 3-disubstitued butyrolactones via tandem hydroxymethylation-lactonization could thus be established. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).