DABCO-based ionic liquids: Green and efficient catalysts with a dual catalytic role for aza-Michael addition

Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane (DABCO) have been synthesized to catalyze the aza-Michael addition of secondary amines to α,β-unsaturated compounds. Among the catalysts tested, [DABCO-PDO][OAc] was found to be most suitable for the reaction of a wide range of cyclic substrates without any solvent at room temperature, and afford the products in good to excellent yields within an appropriate amount of time. The proposed mechanism for the dual activation of the catalyst was supported by experimental results as well as the DFT calculation. In addition, the ionic liquids used can be regenerated and recycled several times without any loss of activity.

Graphical abstractFour recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane (DABCO) have been synthesized to catalyze the aza-Michael addition of secondary amines to α,β-unsaturated compounds.Figure optionsDownload full-size imageDownload as PowerPoint slide