Chiral Imidazolinium Salts: Lewis Acids, Shift Reagents and Ionic Liquids

Significance

Using standard methodology for imidazolidine ring synthesis, new chiral mono- and bis-imidazolinium salts have been prepared in good to excellent yields. The final step involves quaternization and counter anion exchange. These salts show good catalytic activity in aza-­Diels-Alder reactions; however, no asymmetric induction was observed. Tested as chiral shift reagents, the bis-imidazolinium salts were able to resolve the ¹⁹F and ¹H NMR signals belonging to the two enantiomers of the potassium salt of Mosher’s acid.