Fast, acid-free, and selective lactamization of lactones in ionic liquids.

A fast and acid-free one-pot 0.2-30 mmol microwave methodology for direct ionic liquid-mediated preparation of lactams from lactones and primary amines has been developed. The protocol was investigated with a wide range of primary amines and a handful of lactones, including substrates with acid-sensitive substituents. Both gamma-lactams and delta-lactams were, despite the complete absence of a Brønsted acid, obtained in useful to excellent yields after only 35 min of microwave processing.