Formal [4 + 1] Annulation of α,α‐Dialkyl β‐Oxo Amides and Dimethylsulfoxonium Methylide: A Synthetic Route to β‐Hydroxy‐γ‐lactams.

A suggested mechanism of the title reaction involves the nucleophilic attack of an in situ generated sulfur ylide on the carbonyl group of (I), followed by proton exchange and intramolecular lactamization with elimination of DMSO.