Dihydro[c]benzazepin-3-ones via Conjugated Nitrone−Allene Precursors

Treatment of o-propargylaryl nitrones with base provided 1,2-dihydro[c]benzazepin-3-ones in good yields. The straightforward transformation is explained on the basis of a multistep rearrangement involving conjugated allene−nitrones as precursors of a 1,7-dipolar electrocyclization process that is followed by further bond reorganizations.