Biocompatible Ionic Liquid Promote One-Pot Synthesis of 2-Amino-4H-Chromenes Under Ambient Conditions

Abstract

The synthesis of 2-amino-4H-chromenes through one-pot multicomponent reactions has received great attention due to the high atom efficiency and the broad bioactivities of the products. Here, the catalytic performances of a series of functional ionic liquids towards this type of reaction were investigated and the results showed that the ionic liquid, choline acetate ([Choline][Ac]), could efficiently promote this reactions under room temperature without the necessary of organic solvents. The reaction is easy to be conducted and the following work-up procedures are very simple. The pure products can be obtained through extraction and washing procedures, no column separation procedures are needed. Intriguingly, this reaction system can be easily scaled up to multi-gram, suggesting its perspective in industrial applications. In addition, the ionic liquid [Choline][Ac] can be easily prepared from cheap and biocompatible materials, and it can be feasibly recycled and reutilized for at least five cycles. Various aldehydes, malononitrile and activated phenols could be converted to the corresponding 2-amino-4H-chromenes with good to excellent isolated yields under the catalysis of choline acetate at room temperature.