Zwitterionic imidazolium salt: an effective green organocatalyst in synthetic chemistry

An environmentally benign, stable yet efficient organocatalyst is highly desirable from the viewpoint of green chemistry and catalysis. Imidazole-based zwitterionic-type molten salts are a new type of organocatalysts with high catalytic application in various organic transformations with added advantage of room temperature ionic liquid (RTIL) property. Most importantly, these ionic-liquid catalysts are easily recyclable and subsequently reusable for multiple times without loss of significant catalytic efficiency. It has also been evident that C2–H of the imidazole has a vital role in catalyzing the reaction via electrophilic activation. Moreover, by changing the cations and/or anions, the properties of ILs can be tuned in many ways. In this article, the role of imidazolium zwitterionic molten salts as an organocatalyst for selective organic transformations including syn-selective aza-Henry reaction, Erlenmeyer reaction, synthesis of different heterocycles and their functionalization and regioselective ring-opening reactions has been elaborated chronically which will definitely be helping to the readers to explore this new class of organocatalyst for further applications.