Synthesis and Application of a Novel Ionically Tagged Polymer as a Nano-Heterogeneous Catalystfor Synthesis of N-Heterocycle Spiropyrans under Mild and Green Conditions

Nowadays, ionically tagged polymers including cations such as imidazolium, pyrrolidonium,pyridinium and anions such as tetrafluoroborate, hexafluorophosphate, triflates incorrectlyhave been called polymeric ionic liquids PILs [1] .Organic and biological based solid acidsare one of the most applicable compounds which have been used for acid-promoted processesand chemical methodologies. Solid acids have received great attention as general materials fora variety of chemical processes because of their reasonable properties such as nonmetallic,nontoxic, with no generated hazardous waste, reusability and high turnover [2]. Recently, applicationof solid acids with sulfonic acids tags as catalysts comprehensively reviewed [3].The research and application of various multi-SO3H functionalized solid acids are interestingdue to their nano structures, Brønsted acidic and environmentally friendly, good candidatesfor replacing of conventional solid acids, which could be used as a catalyst and reagent [5].Spiro compounds as drug candidates are target molecules for pharmaceutical investigations.The unpleasant effects of oxidative stress on human health have become a serious issue. Herein,a novel ionically tagged polymer was synthesized and used as an efficient and reusablecatalyst for the synthesis of spiropyran derivatives (Fig. 1).