1-Butyl-1-methylpyrrolidinium-1,2,4-triazolide (BMPTz): A Novel Ionic Liquid Solvent for Catalyst-Free N-tert-Boc Protection of Amines under Mild Conditions

Abstract We report the application of a newly synthesized ionic liquid, 1-butyl-1-methylpyrrolidin-1-ium 1H-1,2,4-triazol-1-ide BMPTz, as a reaction medium for the solvent-assisted, N-tert-butoxycarbonylation of amines without a catalyst. A wide variety of structurally distinct amines, such as aryl, benzylic, secondary, and primary variations — reacted smoothly with Boc-anhydride (Boc2O) at ambient temperature to furnish the corresponding N-tert-butylcarbamates in yields ranging from high to excellent (95–98%). No additional catalyst or base was required. The ionic liquid BMPTz proved recyclable, retaining full catalytic activity across five consecutive reaction cycles.