1,1′-Sulfinyldipyridinium bis (hydrogen sulfate) ionic liquid: synthesis and application in the temperature-influenced synthesis of novel pyranopyrimidinediones and pyranopyrimidinetriones

Abstract

A novel and robust dication homo-anionic ionic liquid with the properties of a Brønsted acid is shown to efficiently catalyse the reaction of salicylaldehyde and 6-amino uracil in ethanol to produce novel pyranopyrimidinediones and pyranopyrimidinetriones under ambient and reflux conditions, respectively. The ionic liquid can be synthesized from inexpensive, commercially available precursors. A mechanism is suggested for these transformations. The advantages of this method include novelty in terms of the ionic liquid, together with a high efficiency, easy work-up procedure and purification, convenient operation, mild and environmentally benign reaction conditions.