Quaternary ammonium zinc- or tin-containing ionic liquids: water insensitive, recyclable catalysts for Diels–Alder reactions

Deep Eutectic Solvents: The Organic Reaction Medium of the Century

“…Already in 2002, the efficiency of mixtures composed of choline chloride-zinc or tin chlorides (1:2 molar ratio) as solvents and Lewis acid catalysts was reported for the reaction between different dienes (2,3-dimethylbuta-1,3-diene, isoprene, 1,3-cyclohexadiene, and cyclopentadiene) and acrylaldehyde, but-3-en-2-one, methyl acrylate, and methacrylaldehyde as dienophiles. [77] As depicted in Scheme 17, a high endo selectivity was obtained (up to 97/3), something typical for Lewis acid-catalyzed reactions. In comparison to conventional organic solvents, faster conversions were observed.…”

O-Acetylation of cellulose and monosaccharides using a zinc based ionic liquid

“…These Lewis acidic solvents have been successfully employed for a variety of reactions including Diels-Alder, Fisher indole synthesis and polymerisations. 6,7 In this current study we report that O-acetylation of sugars and cellulose can effectively be carried out using chlorozincate ionic liquids.…”

Acidic ionic liquids based on phosphonium chloride and metal chlorides-recyclable media and catalysts in the Diels-Alder reaction

“…They were based on the other metal chlorides, such as iron(III) chloride, zinc(II) chloride and imidazolium, pyridinium or phosphonium halogenides 3,4,5 . In those catalytic systems the benzylation of aromatic hydrocarbons 4 , the acetylation of benzene 5 or Diels-Alder reaction 6 were carried out successfully. As the merit of using the acidic ionic liquids in comparison to organic solvents, the higher yields and selectivity to the desired product and the simple recovery and reuse of the acidic catalyst have to be emphasized.…”