Knoevenagel Reaction in [MMIm][MSO4]: Synthesis of Coumarins

Molecules

Pedro Verdía¹  Francisco Santamarta¹ 

[1] Department of Organic Chemistry, Faculty of Chemistry, University of Vigo, 36310 Vigo, Spain

关键词: ionic liquid;    Knoevenagel reaction;    synthesis;    coumarins;   

DOI  :  10.3390/molecules16064379

来源: mdpi

【 摘 要 】

The ionic liquid 1,3-dimethylimidazolium methyl sulfate, [MMIm][MSO₄], together with a small amount of water (the amount taken up by the ionic liquid upon exposure to air), acts efficiently as both solvent and catalyst of the Knoevenagel condensation reactions of malononitrile with 4-substituted benzaldehydes, without the need for any other solvent or promoter, affording yields of 92%–99% within 2–7 min at room temperature. When L-proline is used as an additional promoter to obtain coumarins from o-hydroxybenzaldehydes, the reaction also proceeds in high yields. Work-up is very simple and the ionic liquid can be reused several times. Some of the coumarins obtained are described for the first time.

【 授权许可】

CC BY   
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.