Pravadoline synthesis using an imidazolium-based ionic liquid as a green solvent

Abstract

An easily accessible ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) was synthesized, and characterized using ¹H and ¹³C NMR, and MS. The ionic liquid was demonstrated to be an efficient green solvent for the synthesis of pravadoline, one of non-steroidal drugs. High yield was achieved without the presence of an anhydrous Lewis acid catalyst. The reaction was also successfully carried out using other imidazolium-based ionic liquids, including 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF₆]), and 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF₆]). To our best knowledge, this is the first report in Viet Nam on the synthesis of a pharmaceutical chemical in ionic liquids as green solvents.