Base-promoted reactions in ionic liquid solvents. The Knoevenagel and Robinson annulation reactions

When used in place of classical organic solvents, ionic liquids offer a new and environmentally benign approach toward solvation in modern synthetic chemistry. Two classical named reactions, the Knoevenagel condensation and Robinson annulation, have been studied using the ionic liquid 1-hexyl-3-methyl imidazolium hexafluorophosphate, [6-mim]PF6 as solvent. Yields for each reaction were moderate to excellent. In each system the ionic liquid was successfully recycled for reuse in subsequent reaction runs, a factor of key importance to the ‘green’ nature of solvation with ionic liquids.