Diels-AIder reaction between cyclopentadiene and dimethyl maleate in ionic liquids

The reaction between cyclopentadiene and dimethyl maleate was carried out in the ionic liquids (1-alkoxymethyl-3-methylimidazolium salts) or in their mixture with the organic solvent. The effect of the length of the alkoxy substituent and the type of anion (BF4-, PF6-) on the yield of the product, the endo/exo ratio and the reaction rate constant (k2) were studied. The activity of the scandium triflate in the Diels-AIder reaction carried out in various reaction medium (methylene chloride, diethyl ether, methanol, 3-methyl-1-pentyloxyimidazolium tetrafluoroborate) was established.