Succinimidinium N-sulfonic acid hydrogen sulfate as an efficient ionic liquid catalyst for the synthesis of 5-arylmethylene-pyrimidine-2,4,6-trione and pyrano[2,3-d]pyrimidinone derivatives

Succinimidinium N-sulfonic acid hydrogen sulfate ([SuSA-H]HSO4) as a new ionic liquid is prepared and characterized using a variety of techniques, including infrared spectra (FT-IR), H-1 and C-13 NMR, scanning electron microscopy, a mass spectra method, as well as by Hammett acidity function. The prepared reagent is efficiently able to catalyze the preparation of 5-arylmethylene-pyrimidine-2,4,6-triones via the condensation of aldehydes and barbituric acid. Further studies showed that the condensation of aldehydes with barbituric acid and malononitrile leading to pyrano[2,3-d]pyrimidinone derivatives can also be efficiently promoted in the presence of this reagent. The present methodology offers several advantages, including ease of the preparation and handling of the catalyst, simple and easy work-up, short reaction times, high yields of the products and recyclability of the catalyst.