Protic onium salts-catalyzed synthesis of 5-aryl-2-oxazolidinones from aziridines and CO₂ under mild conditions

Protic onium salts, e.g. pyridium iodide, proved to be highly efficient and recyclable catalysts for the selective synthesis of 5-aryl-2-oxazolidinones under a CO₂ atmosphere at room temperature, presumably due to aziridine activation assisted by hydrogen bonding on the basis of ¹H NMR and in situ FT IR under CO₂ pressure study.