2-Pyrrolidinone derivatives are widespread materials of considerable laboratory and commercial importance. In spite of this, there is no generally useful synthesis of either symmetrically or unsymmetrically 5,5-disubstituted derivatives. This is particularly true for those cases bearing aryl substituents. We describe here an effective and general synthesis of 5-mono- and disubstituted 2-pyrrolidinones (including aryl and spiro substituents) from readily available precursors. The flexibility of the reaction sequence should also readily permit the simultaneous introduction of additional substituents at other ring positions. The overall success of the procedure results from the discovery of a novel oxidative cyclization reaction of acyclic hydroxyurethane precursors. © 1981, American Chemical Society. All rights reserved.