One-Pot Van Leusen Synthesisof 4,5-Disubstituted Oxazoles in Ionic Liquids

An efficient and mild protocol for the preparation of 4,5-disubstituted oxazoles through an improved one-pot van Leusen oxazole synthesis in ionic liquids is described. The oxazole products were prepared from tosylmethyl isocyanide (TosMIC), aliphatic halides and various aldehydes in high yields. The recovered ionic liquids could be reused as solvent for six runs without significant loss of yields.